31/07/26 93.5 36.6 0 0 138/83/57 0

30/07/26 94.1 0 0 145/89/54 1

29/07/26 94.3 toohot 0 0 133/79/50 1

28/07/26 94 36.6 0 0 141/83/54 5

27/07/26 93.8 0.001 0.001 131/80/57 2

26/07/26 93 toohot 0 0 2

25/07/26 93.1 toohot 0 0 130/81/48 2

24/07/26 92.1 36.7 0 0 133/86/58 2

23/07/26 91.8 toohot 0 0 130/79/51 0

22/07/26 92.6 36.4 0 0 148/87/54 0

21/07/26 93.4 36.7 0 0 134/84/55 2

20/07/26 94.1 toohot 0 0 138/82/48 2

19/07/26 92.9 36.85 0 0 129/75/57 3

18/07/26 94.3 toohot 0 0 150/92/58 4

17/07/26 94.2 36.4 0.002 0.002 6

16/07/26 94.6 toohot 0 0 134/84/54 4

So it was bumps week, and I had pushing-off duties at 1700 every day, and cycling-around-like-a-lunatic duties after that, which was not really going to fly since I am regularly going to sleep involuntarily at 1700 every day.

And I thought “I am pretty sure that ex150ish used to completely fix all my fatigue symptoms, even though that doesn’t really show up on my sleepy index”. So I hid all the carbs and bought a load of sour cream and crème fraîche, and did a very short bout of ex150ish-sccf.

I didn’t make any predictions, this was a sudden spontaneous whim, but I would have made all the usual ones about ex150ish, to wit (consults previous predictions):

Headaches on ketosis entry. But if I take electrolytes I suspect I’ll be fine and enter ketosis smoothly with maybe a slight ‘ghost of a headache’. Although I have been in ketosis recently and I suspect that doing it twice with not much of a break makes the keto-flu worse.

Non-existent appetite, rapid weight loss, excellent mental clarity, the “two fuels” problem where I can get my mind tired while still having plenty of physical energy. If any of these things don’t happen I’ll be surprised.

I expect to lose 1.5 kg of water-weight immediately as I shed my glycogen reserves, then to lose body fat at around 1kg per week.

Current average is 94 kg, so in one week’s time I expect to be 92 kg, and then to bounce back up by 1.5kg over two or three days whenever I add significant carbs back in, and end up at 93.5kg.

What Actually Happened

Looking at my notes I got a keto-flu headache the first day, despite taking electrolytes, fixed it with ibuprofen and paracetamol, tried to go to sleep early at 1540 just in case, failed to sleep, and then got out of bed around 1700 and did my thing fine and didn’t feel tired until 0100 when I went to bed.

On the second day I got up at 1100, with another headache, fixed it with ibuprofen and paracetamol, and then spent the whole day talking to people and got the two-fuels problem at about 16301. I went for a lie down to try to fix that, and at 1700 I was fine again, and continued to be fine until 2330 when I went to bed.

After that I my notes just say ‘fine all day’ for a couple of days. I didn’t drink at all, partly because by 2100 I didn’t feel like it, and partly because I didn’t want to risk adding a hangover to my usual tiredness problem.

Not feeling like drinking during bumps week is a sign that all is not well, usually the after-races drinking and going on about the old days is half the point. But I felt much better than I have done recently, and had no temptation to go to bed until after midnight, which is normal for me and always has been.

I didn’t actually note any change in my appetite but I wasn’t paying attention. I was living on bits of stew and sour cream so I probably didn’t eat much?

On Friday, the last day, I woke up feeling fine, and noted that I felt the clarity of mind that I expect from ketosis, but then at 1300 I got all weary, went to bed but couldn’t sleep, got up feeling fine at 1400, did all the things, and then decided that I’d recarb and see what happened rather than going to the big post-bumps party.

And then surprisingly I didn’t just fall immediately asleep even though that’s what I’d expect if I ate a load of carbs while in deep ketosis, but I didn’t feel like partying either, I just sat up reading and finally went to bed about 0045 and didn’t wake up until midday the following day.

The funny thing is, although this pretty much worked as expected and allowed me to fulfil bumps-related duties at a time when I’d usually feel pretty shattered and not trust myself to do anything both complicated and slightly dangerous, it hardly shows up on my sleepy index at all.

There were two days of feeling fine, and four days of ‘napfail’, and although if you look very closely at the graph you can just make that out as an improvement, it doesn’t show up as a dramatic difference in the seven day average sleepy index at all.

In its defence I didn’t feel entirely well, people who are entirely well don’t suddenly feel like going to sleep in the middle of the day and then find nothing happens and get up again, but it was much better than usual.

Weight-wise my seven day average went down from 94kg to 92kg and then went back up to 94kg, which is sort of as expected, except that I would have expected that to be 1.5kg of water-weight and (5/7)kg of actual fat loss, which doesn’t seem to have happened.

This does not shake my faith in ex150ish-sccf, which does seem to have worked pretty much as I expected it to do, but it does make me think that there’s a bit of a run-in period at the start for a couple of days, and that the good effects mostly happen after that so that five days in total isn’t enough to see much of them, although I did get a couple of days of feeling normal and one bout of mental clarity worth noting.2

I am no more confused now than I was before.

Since then I’ve been pretty much back to my new normal, which involves failing-to-take-an-afternoon-nap every day around 1700, but there’s been one day when I actually slept, and one day (yesterday) when I felt a bit sluggish for half-an-hour but didn’t feel like actually going to bed so just read for a bit and then felt better.

Oh yes, and a couple of times I’ve felt slight hypothyroid symptoms (plantar fasciitis, achy legs and would you believe a sodding acne outbreak), and taken a very very tiny bit of thyroid, which has seemed to both fix the symptoms and result in me feeling far too hot for a few days. Scylla... Charybdis...)

So, now going back to ‘hands off the controls’ and let everything settle down for a bit and see what I’ve got left. I might experiment with even tinier doses of thyroid if that seems warranted, but honestly at this point I really can’t believe it’s enough to make any difference at all even though it does seem to... OK I am a bit confused about that.

15/07/26 94.2 36.85 0 0 135/71/55 3

14/07/26 93.3 36.8 0 0 153/87/60 1

13/07/26 94 36.9 0 0 143/87/63 5

12/07/26 93.3 toohot 0 0 129/87/60 4

11/07/26 92.6 toohot 0 0 4

10/07/26 92.9 toohot 0 0 1

09/07/26 92 toohot 0 0 135/76/63 4

08/07/26 91 36.5 0 0 140/92/71 0

07/07/26 92.2 36.5 0 0 3

06/07/26 91.5 toohot 0 0 4

05/07/26 91.7 toohot 0 0 3

04/07/26 92.6 toohot 0 0 4

03/07/26 93 36.8 0 0 140/85/66 5

02/07/26 92.9 36.6 0 0 138/84/64 2

01/07/26 93.4 toohot 0 0 142/90/61 7

30/06/26 93.4 toohot 0 0 150/83/58 2

29/06/26 92.8 toohot 0 0 149/90/62 0

28/06/26 93.4 toohot 0 0 131/85/65 1

27/06/26 93.5 toohot 0 0 134/80/59 0

So I didn’t end up doing the proper ex150ish at all, since the minute I ran out of carbs I perked up, and suddenly decided that I would actually enjoy cycling the eight mile round trip to the shops in Burwell in the ferocious heat rather than starving to death. So I did and it was amazing, I was full of energy and joy.

When I got there I stocked up on sc and cf but I carefully didn’t buy any carbs, thinking a few days feeling like this would be nice. But I did buy a bag of carrots, and they tasted great and I ate half the bag.

And the next morning I ate the other half of the bag, because they tasted really really good and I couldn’t stop. They were just standard supermarket carrots, which are usually fairly watery things. But these were so amazing that I got suspicious and asked ChatGPT what carrots had in them that I might be craving.

And pretty soon we worked out that it was carbs. Turns out carrots are basically fruit, and if you eat 250g of them then you might as well have had a grapefruit. No surprise they taste amazing if you’re short of carbs.

Later that same day I headed back to Cambridge because there was stuff, and I was feeling a bit fly-blown and mosquito-bitten and over-swum and was running out of cigars so it was totally time to go back home and get annoyed by real things instead of paradise things.

And when I got back I bought a load of the usual and just carried on doing ex150ish-sccf-low-carbs.

And it carried on working just as before. Fat loss at about 1kg/week, no mental effects at all.

Which is to say I’m still appallingly tired. It’s still rather disabling, I get shattered and need to sleep around five o’clock most days. After a couple of hours sleep I wake up fine though, so it’s annoying rather than horrible.

Eventually after four weeks I recarbed. There was no particular reason to, I think ex150ish-sccf-low-carbs is perfectly sustainable long term. No carb cravings or desire to eat anything else, it’s not even boring, it’s just nice to eat the same thing every day and it’s no trouble.

I felt more like a submarine cautiously surfacing to have a look around than a submarine full of stale air, greeting the surface with joy.

No further sunburn, even though I haven’t been particularly careful and have done a couple more bike rides in the full sun with no shirt on, I think I’ve just tanned enough to stop it happening.

Recarbing has also made no noticeable difference except that my weight stopped dropping and started rising.

Looking at the graph my seven day average was 97.3kg a month ago, and went down to 92kg. Add 1.5kg for lost water-weight and that’s 93.5kg/BMI29.5, so I lost about 4kg of presumably fat over four weeks of ex150ish-sccf-low-carb, and it didn’t seem to be slowing down so there’s probably plenty more weight loss there if I want it, and it’s pretty much effortless.

I don’t want it just yet. Setting a new record low is kind of tempting, but I don’t feel fat at 29.5, 27 would be normal for me, and actually I’m much more worried about the tiredness, which is affecting my activities and quality of life rather than a cosmetic nice-to-have.

My tiredness index seems to have survived me actually noticing that it exists, the sleepyindexsdma is chugging along pretty much as it was, currently 2.65, and that squares with my feeling that nothing much has changed by recarbing.

I’ve got a couple of theories about the tiredness, and neither of them make any sense.

The principal theory is that I’m just a bit hyperthyroid. I am regularly too hot to take my temperature properly in the morning, it is more urgent to get the covers off than to wait ten minutes to get a proper reading. There’s should be almost no exogenous thyroid in my system any more, I haven’t taken any for a full month, I was taking minute amounts before that, and it should all have decayed away by now.

But I’ve got no other hyper symptoms. And the weather here is still hot, but I’ve started to think of it as ‘quite nice’ rather than ‘this is a bit much’.

The second one is that all these big weight yo-yos have screwed me up somehow, my system is full of PUFAs released from lost fat, and that’s screwing up my metabolism generally (glycolysis is blocked!). That explains the sunburn incident, since PUFAs should cause sunburn. But it should also mean I’m running cold, which I’m absolutely not. And I don’t have any hypometabolic symptoms at all, except the tiredness.

I’ve also heard that losing weight tends to make people a bit hyper, something about stored thyroid being released from fat cells, so it may be that I’m simultaneously full of PUFAs and excess thyroid hormones, but who knows?

Or maybe I’m tired for completely different reasons. Perhaps I have developed a second inexplicable fatigue disorder. Oh joy.

I’m just going to take my hands off the controls for a bit and see what I’ve got left when it’s all settled down.

Predictions

Mysterious tiredness just goes away for mysterious reasons over the next few weeks.

If it’s caused by some side effect of weight-loss then I won’t be doing that for a bit. If it’s something to do with my own thyroid being slightly out of whack because I’ve been playing silly buggers with it for years then it should eventually go back to normal.

Weight goes up.

Since my set point was 99kg three years ago, and 96.7ish last time I checked a year and a half ago, it should be down around 94.5kg by now if that decline is just ‘something to do with not eating processed food any more, but it takes years to fix’.

On the other hand if it’s ‘no PUFAs’ specifically, then the recent huge weight yo-yos should have dumped a load of PUFAs from body fat, and it should be lower than that.

On the third hand, those PUFAs have probably been released into my system and caused various types of chaos, in particular stopping leptin getting to my lipostat maybe?

So if all those things are simultaneously true, I’m guessing that my weight should go back up to a bit more than 94.5kg, and then start to settle lower as the acute PUFA damage clears, eventually ending up a bit lower than 94.5kg and stable. 94.5kg is BMI 30 for me, I’ll be happy enough with that although a bit lower would be nice.

I should at some point go and bother my doctor for a full blood panel in case something completely different has gone wrong, but I’m going to give it a couple of months so I can present them with a system closer to a settled equilibrium state than it probably is now.

Wish me luck!

And I concluded that I’d expect a hypothetical objective measure of fatigue to have the following properties:

• Vague constant fatigue ever since 2023, which is nevertheless a noticeable improvement on my previous state, which was itself not too bad

• In summer 2023, very few afternoon naps or failed afternoon naps

• Dramatic improvements in deep ketosis, mild improvements in half-hearted lowish carb diets

• Low fatigue levels in the run up to Christmas 2024

• Increase in fatigue after Christmas 2024 to the point where I told my boss it was affecting my work (so ‘slightly disabled’ rather than just ‘limited’)

• Recovery after that

• Massive fatigue August 2025 on, probably explained by thyrotoxicity, getting worse and then better over the period I was home

• Massive fatigue early Christmas 2025, explained by sulphite poisoning, but getting better later on

• Followed by improvements to the point I felt able to write the fatal words: ‘The almost complete remission of my once-crippling chronic fatigue’

• Followed by quite bad hypo-type fatigue, improving and then getting worse as I went hyper again.

• Followed by really bad hyper-type fatigue over Easter 2026

• Followed by bad hypo-type fatigue, slowly improving until I start being a bit hyper again and get more fatigue.

• Eventually leading to my June state of being totally off the thyroid and still irritatingly hot all the time and still fatigued

• And finally now, in mild ketosis for a while, fatigue lessening notably to the point where it’s just ‘limiting’ again rather than ‘disabling’.

I can’t get any sort of objective measure, I don’t even know how to do that in principle, but I have about three years of daily notes in electronic form, and I’ve data-mined those records.

Wherever I’ve said “nap”, which means I’ve gone to sleep for a bit during the day, that counts 4, and “napfail”, which means I went to bed but didn’t sleep, that counts 2, and if I said “shattered”, that counts 2, and any of “sleepy”, “sluggish”, “woozy”, “tired” count 1, and “tiredish” counts 0.5.

So for instance my notes for 10/04/26 say “woke 1100, fine, achy legs in pub, 1830 tired, napfail, dinner, shattered, another nap, fine, bed 0100, headache”

That seems to have been a particularly bad day, and counts 9. Most days are quite a lot better than that.

And I’ve plotted a graph of that index, and taken a seven-day moving average as usual, and here it is:

Looking at that the first thing I notice is that it’s really very noisy! Even the seven day average is jumping around all over the place, but it’s roughly consistent with all the blog posts, in that from 2023-2025, it’s hovering around 1/day, which is to say that most days I’ve got just enough fatigue to remind me that I’m not in good health, but it’s not really a problem.

And then new year 2025 there does seem to be some increase in fatigue for some reason. But there doesn’t seem to be much evidence of recovery, it’s just getting worse. And in July that year after I left my gig at Midsummer Energy it gets much worse, then when I go home to visit Mum in August 2025 it goes away completely, and then comes back in the second half of that visit.

After that it seems to decay away, until by Christmas 2025 it’s hardly a problem at all, at which point I said the bad thing.

Then in the early part of Christmas it got bad again, then went away, and then when I came back it got really bad, and then decayed away.

And then Easter 2026 it was really really bad, and then it’s kind of decaying away for a bit, but recently it’s got worse again, and my current ex150ishsccf+low-carbs initially seemed to help, and now it’s got quite a lot worse again.

And it’s currently quite bad! Most days I need to at least try to sleep in the middle of the day, and on a typical day I have fatigue symptoms.

I really don’t trust this measure at all! Self reports of psychological symptoms are about the worst metric you can track, because the threshold where you actually decide to go and write something down is very highly variable, and it depends on what you think is going on, so you can’t help but fiddle it to conform with what you think is happening.

Still, it’s all I’ve got, and now I can’t use thyroid dose as a more objective proxy for healing (because it’s gone to zero, and I’m still a bit overheated, so I think it’s probably gone to zero for good) I think I’m going to add it to my graphs.

I think at least it’s enough to confirm my subjective impression that my tiredness was not so bad for the first couple of years, but is now becoming a real problem that is affecting my life quite negatively, and stopping me doing things I want to do, and also making me much stupider than I like to be.

I can look at it, and think, yes, all pretty stable until Christmas 2025, and then just getting steadily worse for the last eighteen months.

This is what it looks like added to the usual graph, with thyroid and waking temperature crushed down very small, because you can see everything you need to know even when they’re very shrunk.

If I score my desiderata:

Vague constant fatigue ever since 2023, which is nevertheless a noticeable improvement on my previous state, which was itself not too bad

TRUE (although I can’t see the previous state)

In summer 2023, very few afternoon naps or failed afternoon naps

FALSE (fatigue actually seems worse then than before or after, all through the mysterious honeymoon period I was apparently quite tired, and occasionally napping)

Dramatic improvements in deep ketosis, mild improvements in half-hearted lowish carb diets

UNKNOWN (I can read it that way if I stare at it, but it’s not obvious, and in my memory it was obvious)

Low fatigue levels in the run up to Christmas 2024

TRUE (That does appear to be the least tired I’ve been since i started keeping records)

Increase in fatigue after Christmas 2024 to the point where I told my boss it was affecting my work (so ‘slightly disabled’ rather than just ‘limited’)

TRUE (but it’s only gone back up to what it had been previously)

Recovery after that

FALSE (again, that’s a clear memory and I wrote about it at the time, but it’s not visible on the graph)

Massive fatigue August 2025 on, probably explained by thyrotoxicity, getting worse and then better over the period I was home

FALSE (I went home, and the fatigue went away completely for a couple of weeks, and then came back stronger. After that it decayed steadily away for a couple of months until it was nothing by Christmas)

Massive fatigue early Christmas 2025, explained by sulphite poisoning, but getting better later on

TRUE (A big spike in fatigue while sulphited)

Followed by improvements to the point I felt able to write the fatal words: ‘The almost complete remission of my once-crippling chronic fatigue’

TRUE ( followed by recovery to almost nothing again)

Followed by quite bad hypo-type fatigue, improving and then getting worse as I went hyper again.

TRUE (steady improvement even though I was losing weight, then it starts getting worse)

Followed by really bad hyper-type fatigue over Easter 2026

TRUE (most tired I’ve ever been by the look of it)

Followed by bad hypo-type fatigue, slowly improving until I start being a bit hyper again and get more fatigue.

TRUE (gets better and then gets worse)

Eventually leading to my June state of being totally off the thyroid and still irritatingly hot all the time and still fatigued

And finally now, in mild ketosis for a while, fatigue lessening notably to the point where it’s just ‘limiting’ again rather than ‘disabling’.

TRUE (although that improvement seems to have reversed since I wrote it, and in this case I think that’s because it was Kate’s birthday and that involved a startling amount of whisky and a fairly predictable hangover, and I am still feeling a bit out of sorts two days later)

That’s nine TRUEs, three FALSES, and one UNKNOWN, which is really not very impressive since I’d already seen this graph when I was reading through my notes.

Going forward, I think this measure will be even worse as a metric, because now I know it’s going to get data-mined and graphed, I’m not going to be able to avoid unintentionally biasing my records.

I think I’m going to try to aim for ‘every time you feel even a bit tired, write it down’.

That will probably make this metric jump much higher, but it should still be true that if I ever get back to what I’d consider good health, it should go to zero. I don’t think it’s at all normal to be tired enough to make a note of it if you’re in good health and you haven’t been doing some kind of hard physical labour for a few hours at least.

One thing that’s really conspicuously missing from this graph is my very clear impression that when I’m in deep ketosis1, I get hardly any tiredness.

And that really should be there, so I’m going to stare at everything very hard and work out if I’ve made some sort of terrible mistake. But at the moment I can’t see it. I think it’s more likely that this is just a really bad measure to be looking at2.

But it’s all I’ve got, so I’m going to add it on a permanent basis, and maybe try to come up with similar things for hypo- and hyper- thyroid symptoms, which might make what’s going on a bit clearer.

My suspicion that this recent tiredness is somehow related to recent massive weight yo-yos doesn’t seem borne out here either!

It’s definitely true that since I wrote https://theheartattackdiet.substack.com/p/yo-yo-theory in October 2025, my weight has been yo-yoing much more than before3, and it does kind of seem that periods of large weight loss were followed by increases in fatigue levels, whereas long periods of rising weight seem to also be periods of slow decay of fatigue, but it’s not at all jumping out at me from this graph, and there are two great fat obvious counterexamples.

The first is the six-month honeymoon period after I first gave up all PUFAs, when I just lost weight effortlessly for four months. At that point I think I must have had more linoleic acid in my body fat than ever before or after, and must have been dumping quite a lot of it into my blood, and yet it doesn’t seem to have made much difference fatigue wise. That was also a period of steady decrease in thyroid dose, which is also weird if PUFAs in the blood are slowing my metabolism. I wonder if that was a period where I was just usually slightly hyper?

And the second is the recent Easter 2026 Mom Test, where I gained a ton of weight (so probably very little PUFA coming from stores), and yet the fatigue was really bad, worst it’s been since I started keeping records. In that case, that probably was a period of hypermetabolism.

But there’s really nothing clearly going on here, even the things I expected to see like ‘ex150ish fixes my tiredness’, just aren’t obviously there, even though you can sort of see it if you squint.

The only thing I think I’ve learned from doing this is that my subjective strong impression that the fatigue has been much worse recently is probably true.

But I’m not even sure about that. I may have just been paying it more attention...

I am not happy! And I notice that I am as usual, very confused. And so at least one of the things I believe must be fiction.

The only reason it’s a blog post at all is because writing blog posts helps me think and keeps me honest, but that doesn’t mean you have to read it! Just having-had-the-intention-to-publish will do, and I’ve already done that. Now I have to follow through or my brain will learn that I am cheating it.

But if anyone does have the heroic patience and attention to detail to plough through it and check various past posts to find out how I’m fooling myself this time I’d really really appreciate corrections.

So, I started all this PUFA avoidance about three and a half years ago in an attempt to control my new and rapidly worsening obesity problem, and I know that that’s what most of the people who read this blog are interested in.

But that’s not actually what I’m interested in! Or at least, not the most important thing.

At first PUFA avoidance was just a half-hearted sort of thing, because I was thinking ‘There’s no way I can work out if this is true or not, I’ll just have to try it’ and for the first six months it didn’t seem to be making the slightest bit of difference to my rising weight so I wasn’t taking it very seriously.

Although even then, even before I’d finally noticed how much PUFA was in peanut butter and stopped eating it, I did notice and write:

In terms of general well-being, it’s a massive win, in fact my general state of health improved to the point where the deleterious effects of sulphites became obvious, which has lead to me feeling even better. No more mysterious tiredness in the afternoon, no more afternoon naps.

The thing that really grabbed my attention was the fact that the first time I tried the ex150ish diet it completely fixed my tiredness, and I wrote:

But suddenly I’m not so interested in weight loss per se

I’m completely derailed and nerd-sniped by the feeling of ketosis itself.

I’ve got suddenly limitless energy.

This is almost how I used to feel, back when I would have described myself as well.

The feeling that I might suddenly get tired, or that before doing something I should make sure that I’m properly rested and prepared, that I’ve had on and off since I was about forty, is quite gone.

I feel like the famous Duracell Bunny. Nothing slows me down or tires me.

For ten years I’ve been a Spoonie. Now I have as many spoons as I like.

Conversation, walking, playing chess, cycling, none of this is remotely tiring any more. Once you do one thing, on to the next.

I remember that I’m extremely extroverted. When I finish talking to people I feel energized, and my first thought is that now I need more people to talk to.

Friends agree. I’m back to my old self, before it all went wrong.

For the record, apart from the extroversion, I think this is how men are supposed to feel.

I’m pretty sure that’s how I felt for the first forty or so years of my life, with a brief exception when I lived in London while trying to do a PhD, where I got mysteriously tired and depressed and put on weight. 1

I also wrote at the time:

But it feels thin, somehow.

I don’t feel like I’ve got extra power in reserve. I could handle a long slow rowing outing in this state, I think, but I wouldn’t want to do a regatta.

I remember this feeling!

This “ketosis” is the post Boston Marathon, post cycle to Oxford feeling.

When you’ve burnt all your carbs and are running on the emergency back-up fat burning system. (doh!)

And I noticed the “two fuels” problem that same week, where I could get mentally tired while still having endless physical energy.

And I pretty quickly guessed that my long curse of tiredness is actually ‘broken glucose metabolism’, which I strongly suspect is something to do with PUFAs.

For me, this is way way more important than what I happen to weigh on scales. At 100kg/BMI 32 I am a bloated and unnatural horror, but not so bloated that I frighten children, and at fifty five years old I am long past the point where I worry about whether I’m attractive or not. But I didn’t even notice I was getting heavier until the pandemic in 2020, when for unrelated reasons I weighed myself for the first time in years and was surprised to find I was 93kg/BMI 29 instead of the 85kg/BMI 27 which had been ‘my weight’ for my whole adult life.2

So I consider getting rid of this long curse of fatigue to be the primary outcome of all my experiments, and the weight aspect is a nice-to-have but not the important thing.

And so I’m in the bizarre position of trying to do experiments to measure the change in something that’s basically impossible to measure objectively.

For a long time I’ve contented myself with measuring the daily dose of thyroid drugs that it takes to keep me basically functional and not showing the symptoms of either hypometabolism or hypermetabolism. That’s a pretty objective measurement because if I’m hypo I tend to get plantar fasciitis almost immediately, followed by a whole host of other nasty symptoms if I don’t fix it quickly. And if I’m hyper I’m overheating, anxious, a bit manic, and have trouble sleeping.

And that thyroid dose has gone pretty monotonically down over the last few years, which I’d assumed was evidence that the actual underlying problem was getting fixed.

But that’s kind of useless now, because the amount of thyroid that I seem to need has gone so low that it’s practically homeopathic, and indeed at the moment I can’t tolerate any of it at all.

And to my surprise I’m still really tired, in fact it’s worse than I can ever remember it being since I had, and should probably have been diagnosed with, actual mysterious Chronic Fatigue Syndrome, which was a life-ruining wasting horror, even though at its worst it was only quite a mild case. Pity the real sufferers out there, there are a lot!

My made-up-against-medical-advice thyroid cure almost completely fixed all that. I used to say that “my only medical problems these days are sports injuries”, and that was true, but I was never really ‘back to normal’. I was never an endurance athlete after that, stopped rowing, stopped cycling3, stopped skiing, even stopped travelling, and sports I’d once thought of as ‘barely even exercise’, like village cricket and crap tennis, took some dedication to keep playing, and an old friend from rowing days (who’s the same age as me) once rather memorably described me as a ‘limited man who’s learned how to live within those limits’, which struck me at the time as an extremely insightful and inarguably true description.

But now it’s back, and it’s bad. I’m pretty regularly feeling the need for an afternoon nap, and sometimes I actually sleep, and wake up feeling refreshed, and sometimes I just lie down for a bit and then feel fine, and sometimes I sleep and then wake up still feeling tired.

At that point I’m not ‘limited’. I’m ‘mildly disabled’. If I have plans for the evening like singing or playing chess or meeting friends then I tend to take a preparatory nap just in case.

But there are at least no other hypometabolism symptoms. If there were I’d just raise my thyroid dose to fix them. But at the moment if I try that I just get hyper and overheated, and still tired.

So as far as I can tell, all the other symptoms of CFS are completely gone, and yet the principal symptom of tiredness is back. Not as bad as it once was, but still disabling, not just a minor annoyance any more.

What Do I Know About My Fatigue Since 2023?

Well I have my notes and my various blog posts! And I have a definite impression that ketosis always improves things.

For the first year or so (Summer 2023-Summer 2024) I don’t remember paying much attention to fatigue, which implies that it was just burbling along annoyingly in the background, but not much of a problem.

And in the autumn of 2024 through to the summer of 2025 I had an actual full time nine-to-five consultancy contract.

And I remember that for the first half of that, to my surprise, I didn’t have much in the way of fatigue at all, even though it involved an hour of cycling to and fro every day, but that at Christmas 2024 I went home to visit Mum and came back with a real fatigue problem.

It was getting so that I routinely felt shattered and listless and not very productive at all around three o’clock, and started leaving work early to go home and sleep. That seemed the honest thing to do as a contractor paid by the hour, and quite often I’d go home, sleep, feel better, and then go back and work the evening.

After a month or so of this, I felt that I had to tell my boss, who is also a personal friend, that I was not firing on all cylinders, and he was very very understanding. He just said: ‘Do what you can, go home when you need to, you’re good enough that I want you working on this even part-time if you can’.

And weirdly quite quickly after that I just got better again, and for the rest of the spring and early summer of 2025 I was pretty much fine.

By May 2025 I was happy that I’d come to some sort equilibrium weight at 97kg, and I started messing about with variants of ex150 that involved eating carbohydrate (fruit, chips, ice lollies, ice cream). Some of those choices were made because we were having a very hot summer and I was persistently overheating, noticeably more so that other people around me.

It doesn’t actually look like I tried dropping my thyroid dose at this point, I guess I was just assuming that the problem was the heat, until June when it became obvious:

June 2025

It’s been very hot here (around 30C) and I’ve been consistently overheated for the last week, sometimes super-energetic, sometimes very tired, sweating and walking around with no shirt on even though other people seem to be managing ok and some weirdos seem to have managed to feel cold at times. That is pretty clear hypermetabolism/thyrotoxicity, I’ve got no hypo symptoms, and I’ve been dropping doses of thyroid to try and deal with it and that seems to have worked.

I left that gig in July 2025, project done and it was Summer so I didn’t feel like doing any more, but it wasn’t fatigue or even boredom, I was still enjoying it, it was just ‘it’s sunny out’.

It sounds like for a while afterwards I managed to be mainly hypermetabolic, with associated tiredness. It is very irritating that tiredness and fatigue are symptoms of both hypo- and hyper-metabolism, but all the other symptoms are pretty distinct, so it’s usually not that difficult to tell which state you are in as long as it’s not just tiredness.

July 2025

My thyroid dose has dropped a fair bit, I’ve been getting less overheated and I’m feeling fine.

And then when I tried adding bread to ex150ish, I became suddenly hypometabolic, also with associated tiredness

July 2025

neither of those things would have bothered me too much but after a couple of days I also suddenly started getting tired. Three times in the last four days I’ve started feeling really sluggish and brain fogged, gone to bed mid afternoon and slept for a couple of hours. And one day I got a really characteristic ache in my legs which has always been an early-warning chronic fatigue symptom. And I got a surprisingly low waking temperature reading one morning for no reason.

And then hyper again:

July 2025

And it has made no bloody difference at all, I have continued to feel really tired, lots of afternoon naps, overheating horribly and sweating all the time, headaches, weight rising rapidly, and blood pressure now through the roof and frankly scary high.

I’m occasionally feeling tired, but not usually to the point of sleeping in the afternoon, and some days I’ve felt lively.

July 2025

I’m still feeling a bit too hot generally and dropping my thyroid dose to compensate, it’s almost nothing now, so I wonder if all that was just thyroid overdose.

And when I went to visit Mum in August 2025 I was frankly hyper:

August 2025

But it didn’t, I felt far too hot, I couldn’t sleep, my mind was racing, and I was simultaneously exhausted from lack of sleep and full of restless energy.

And then after that, having reduced my thyroid dose down to nothing, hypo again:

October 2025

So there was a period after I came back from home where I wasn’t taking any thyroid and was fine. But in the two weeks since then I’ve felt increasingly sluggish and tired, and eventually last week I started getting plantar fasciitis again, a very characteristic pain in both feet which has always been a hypometabolism symptom for me.

And then after that everything just got a lot better and I started to feel fine again:

And then last Christmas (2025) I maledicted myself by writing:

‘The almost complete remission of my once-crippling chronic fatigue is the best of them’

And as I remember I wrote that because my fatigue, although still present, was not much of a problem, and my necessary thyroid dose was down to very low levels, without any hypometabolism symptoms at all.

Christmas 2025, I managed to poison myself by eating for several days a curry that Mum had unwittingly made with sulphites, and that made me feel terrible, very characteristic nasty headaches and shattering tiredness, but once I’d got through the curry and found the source of sulphites I recovered rapidly and completely, while eating a lot and putting on loads of weight.

But then I came back to Cambridge:

The only fly in my ointment is that I’ve been feeling absolutely awful. I’ve had a couple of mild sniffles in the last couple of weeks, and maybe they were something to do with it. I can’t believe that a couple of weeks ago I wrote ‘the near-complete remission of my chronic fatigue syndrome’. It’s totally back now.

It’s not nearly as bad as it was before I started taking thyroid, and I’ve got none of the many other symptoms apart from the tiredness, but most days for the last couple of weeks I’ve been waking up feeling a bit sluggish, and then by five o’clock I’m so tired I go to bed for a couple of hours, and usually wake up fine and end up going to bed late and the cycle repeats. I feel more tired than I have done for years, and I’m ignoring all sorts of things that need doing.

which sounds like a fair description of my recent state too. That sounds like mild hypometabolism with no other symptoms.

And then it got better (February 2026)

Fatigue-wise things do seem to have got better. Mostly I’m fine, mostly my records say “fine all day”. There have been occasional afternoon naps in the last couple of weeks but they feel tactical as in ‘I have something to do later, I am going to lie down and close my eyes for a while so I have the energy to do it’, rather than ‘Oh God I am shattered and I am going to bed until I feel ok’. Still fatigue, still unusual and a disease I would like to be rid of, but not as bad as it was.

And better again (March 2026), but starting to show hyper symptoms again

Fatigue totally gone, records show a mixture of fine all day, unusually energetic, too hot, and hypomania (which is the state just short of proper mania where you’re really enthusiastic about things and your to do list just disappears). Occasionally feeling tired and going to bed but not able to sleep. Also my morning blood pressure readings are spiking. I am clearly thyrotoxic.

And carried on like that (April 2026):

Three times that week I was tired enough in the afternoon to try going to bed, but then found that I couldn’t sleep and got up again feeling fine. Otherwise I was fine.

At that point I got the train home to visit Mum. I actually felt quite sleepy on the train, but couldn’t sleep and recovered after about half an hour.

And then I once I was home at Mum and Dad’s again I put on a ton of weight as usual, and felt even more tired again, although this time it sounds like that was quite serious hypermetabolism:

Every day I’ve come home tired and most days I’ve gone for a lie down, but I’ve only actually gone to sleep a couple of times. Most days I just lie down for half an hour and then feel fine. At all other times I’ve been quite lively and bouncy, not much trace of fatigue except immediately after walks.

I’ve often been too hot and my waking temperatures have consistently been higher than 36.7C.

Often eating makes me break into sweat, which is not at all normal.

I’ve dropped my thyroid dose in an attempt to control this, and it seems to have helped with the tiredness as well as the overheating. No obvious hypometabolism symptoms so far.

Which tiredness partially fixed itself once I’d stopped taking thyroid, but was still present in the form of post walk attempts to sleep, which I think mostly turned into ‘just lying down for a bit and then feeling ok’:

I’ve basically been forced off the thyroid. Even the tiniest amount now seems to be making me overheat so I’m just not taking it any more, and by my calculations the amount still in my blood is about 1/700th of what was once my daily dose.

Fatigue-wise nothing much happened, still mostly fairly lively, but still getting really tired after going for a walk and needing to lie down, then recovering quickly.

In the same post I actually predicted that I’d lose a lot of weight and feel shattered as a result

At that point I’ll be living on my own considerable body fat, which is still full of PUFAs.

I predict that that will make me feel unwell in various ways, most notably a remarkable increase in fatigue.

And that duly happened, and then seemed to improve slowly (May-June 2026):

The first week back I was about as tired as I’ve been since I first discovered that thyroid would fix my fatigue. It’s more a question of ‘I need to sleep a couple of hours in the afternoon most days’ than ‘full-blown chronic fatigue syndrome’. I never did decide that it was bad enough to go into ketosis, mainly because I’ve been curious as to what would happen if I just left my hands off the controls. The fatigue does seem to be getting better as the weeks go by. I’m still a bit generally sluggish, but although three times this week I’ve felt tired enough to try going to bed, I haven’t actually slept during the day this week at all.

and then it just plateaued at ‘failing to sleep at around 1700 every day’ (June 2026)

the fatigue does seem to be moderating, but it’s still there, mainly manifesting now as a need to go to bed every day at around 1700, but not actually resulting in sleep, just lying down for a bit and then feeling better an hour later. But also periods of sluggishness randomly at other times.

and then I went into a sort of half-hearted version of ex150ish with some carbs in, which has helped but didn’t actually fix the problem:

I do feel much better than I did, but it’s not the usual blinding clarity and inexhaustibility that I get in deep ketosis, and I haven’t seen the “two fuels” problem either. Hypothesise that I still have some carbs around and that means my brain isn’t running entirely on ketones, so I’m still a bit screwed because glycolysis is blocked.

Which is the state I’m currently in, although now I’ve run out of fruit and milk and so I think I’m now going into deeper keto.

That’s about it for fatigue related memories and what I can do by mining my own blog posts.

OK, What on Earth?

So I’m currently thinking that the problem here is that something to do with these massive recent weight yo-yos is affecting my metabolism, actually speeding it up and slowing it down, and that I’m failing to adjust my thyroid dose quickly enough to compensate, and so I’ve been alternating between hyper and hypometabolism for the last year or so. And obviously I’m going to blame that on PUFAs because I’m a single-issue monomaniac.

And I’m also noticing that the big drops in thyroid dose have mainly happened in the summer months, which make overheating much more of a problem than it is at other times of year. In winter being a bit warmer than you’d expect is just nice, but in summer it’s actively unpleasant and so you really notice it.

A Hypothetical Objective Measure of Fatigue

So if I actually had some objective measure of my fatigue, which I’d been carefully recording all these years, I’d expect it to show:

Vague constant fatigue ever since 2023, which is nevertheless a noticeable improvement on my previous state, which was itself not too bad

In summer 2023, very few afternoon naps or failed afternoon naps

Dramatic improvements in deep ketosis, mild improvements in half-hearted lowish carb diets

Low fatigue levels in the run up to Christmas 2024

Increase in fatigue after Christmas 2024 to the point where I told my boss it was affecting my work (so ‘slightly disabled’ rather than just ‘limited’)

Recovery after that

Massive fatigue August 2025 on, probably explained by thyrotoxicity, getting worse and then better over the period I was home

Massive fatigue early Christmas 2025, explained by sulphite poisoning, but getting better later on

Followed by improvements to the point I felt able to write the fatal words: ‘The almost complete remission of my once-crippling chronic fatigue’

Followed by quite bad hypo-type fatigue, improving and then getting worse as I went hyper again.

Followed by really bad hyper-type fatigue over Easter 2026

Followed by bad hypo-type fatigue, slowly improving until I start being a bit hyper again and get more fatigue.

Eventually leading to my June state of being totally off the thyroid and still irritatingly hot all the time and still fatigued

And finally now, in mild ketosis for a while, fatigue lessening notably to the point where it’s just ‘limiting’ again rather than ‘disabling’.

You can tell I’m feeling better because I’m spending days writing incredibly verbose and tedious blog posts that involved reading lots and lots of other blog posts, and writing computer programs, and other activities which have not looked like much fun recently.

And also I suddenly felt like the eight mile cycle to Burwell and back for supplies looked like it would be fun, and I did it, and I didn’t get tired at all. It felt like when I was young and fit and cycling across France in the heat mainly looking for food, or at least like the last time I was in Wicken Fen for long enough to need supplies, back at the start of all this, and now I do not have to starve to death in the wilderness out of sheer laziness.

The reason I am thinking about all this is of course because I have come up with a hopelessly bad method of estimating my fatigue over this period, and I want to check that what I’m looking at makes sense.

But because I’m actually looking at the damned thing right now, and trying to compare what it says with what I remember and wrote, and chasing up anomalies, I can’t help but have fiddled my own results.

So if anyone wants to go trawling through past blog posts to find out where the above story I’m telling is full of shit, now is the time to do it, before I show you what I came up with and it’s not possible to pretend you haven’t seen it any more.

God it would be so nice to have a real mind, where you could just spin off a subprocess that didn’t know something, and get it to do this without cheating. But I am human, this piece of crap is all I’ve got.

27/06/26 93.5 toohot 0 0 134/80/59 0

26/06/26 93.9 toohot 0 0 143/81/62 3

25/06/26 94.1 toohot 0 0 0

24/06/26 94.1 toohot 0 0 139/74/62 4

23/06/26 93.8 toohot 0 0 4

22/06/26 94.7 36.8 0 0 1

21/06/26 94.7 36.9 0 0 154/98/65 1

20/06/26 95.6 0 0 151/93/58 4

19/06/26 96.2 36.7 0 0 166/81/50 2

18/06/26 96.7 36.75 0.003 0.003 144/78/52 2

17/06/26 95.8 36.8 0.003 0.003 143/85/56 4

16/06/26 96.5 36.95 0.003 0.003 0

15/06/26 96.8 36.95 0.003 0.003 6

14/06/26 97 36.6 0.004 0.004 136/77/53 7

13/06/26 97.8 36.8 0.004 0.004 137/82/51 2

The plan for the last two weeks was to eat standard ex150ish, but to allow myself ad-lib sour-cream and crème-fraîche and also to allow myself a piece of fruit every day and milk for my tea.

Predictions From Last Post (edited for clarity)

I predict with some confidence but not the high confidence I’d usually have:

Mild headaches on ketosis entry. But it’s usually pretty smooth if I remember to take electrolytes for the first few days. Note to self, remember to take electrolytes!

Excellent mental clarity, and the “two fuels” problem where I can get my mind tired while still having plenty of physical energy.

Non-existent appetite, rapid weight loss.

I expect to lose 1.5 kg of water-weight immediately as I shed my glycogen reserves, then to lose body fat at around 1kg per week.

Current average weight is 97.3 kg, so in one week’s time I expect to be 94.8 kg, and in two weeks time 93.8kg, and then I expect to bounce back up by 1.5kg over two or three days whenever I add significant carbs back in.

If it doesn’t cause any weight loss at all I’ll be quite surprised, but I won’t be too surprised if it doesn’t work as well as usual, or do the same things but slower, and if it’s obviously not working at all then I’ll probably cut the remaining carbs.

What Actually Happened

Pretty much according to plan, except it turns out I’m incapable of having cold milk in the fridge without occasionally taking a swig of it, so I’ve gone through 8 pints of whole milk in the last two weeks. I probably didn’t have a piece of fruit every day, but most days I had an apple or a grapefruit, usually but not always with cream, which is really nice.

About half way through I fled into the fens on my boat (the weather is really hot!) and it turns out cream doesn’t keep for long in a boat fridge in hot weather, so the gone-off stuff went in the river, and the last few days all I’ve had in the cream line is the sour-cream and crème-fraîche, both of which it turns out I like to eat with lime juice (squeezed straight from the lime), and salt.

Mild headaches on ketosis entry. But it’s usually pretty smooth if I remember to take electrolytes for the first few days. Note to self, remember to take electrolytes!

Not that I noticed! I hypothesise that the fruit and milk made me shed my glycogen reserves more slowly. I did remember to take electrolytes and perhaps the combination got rid of the keto flu effect.

Excellent mental clarity, and the “two fuels” problem where I can get my mind tired while still having plenty of physical energy.

No. I do feel much better than I did, but it’s not the usual blinding clarity and inexhaustibility that I get in deep ketosis, and I haven’t seen the “two fuels” problem either. Hypothesise that I still have some carbs around and that means my brain isn’t running entirely on ketones, so I’m still a bit screwed because glycolysis is blocked.

Non-existent appetite, rapid weight loss

I expect to lose 1.5 kg of water-weight immediately as I shed my glycogen reserves, then to lose body fat at around 1kg per week.

Current average weight is 97.3 kg, so in one week’s time I expect to be 94.8 kg, and in two weeks time 93.8kg, and then I expect to bounce back up by 1.5kg over two or three days whenever I add significant carbs back in.

For the first week my appetite was non-existent, but I thought the weight loss wasn’t happening, I’d just lost 1.5kg of water-weight and nothing else. Which seemed weird. But then on the eighth day I suddenly dropped a kilo to 94.7kg so pretty much bang on schedule and I’m now 93.8kg, slightly lower than expected. Put that down to noise, I think, although it may be that this actually works slightly better than ex150ish, but with a slower lead-in period.

I haven’t put the carbs back in yet.

If it doesn’t cause any weight loss at all I’ll be quite surprised, but I won’t be too surprised if it doesn’t work as well as usual, or do the same things but slower, and if it’s obviously not working at all then I’ll probably cut the remaining carbs.

Called it I think! Weight loss wise it seems to be as good as ex150ish, which is high praise indeed. Mentally/physically it’s not quite as good, but that’s all a bit subjective anyway and it’s worked well enough that I haven’t felt the need to cut the carbs.

In fact the real joy here, which I didn’t formally predict but was hoping for, is that I have no carb-cravings whatsoever. My two weeks is up today, I’m currently sitting outside a cafe that sells nice ice-cream, I’ve tried fantasizing about chips and pizzas and so on, and as far as I can tell, I have no particular desire for any of those things. So I’m just going to stay keto for a bit.1

I didn’t have any particular predictions thyroid-wise, but in the hot weather I’ve been overheating constantly, so I stopped taking it altogether.

Surprise Sunburn

This week I got sunburn!

I’ve never particularly got sunburn, even pre-giving-up PUFAs. I tend to avoid the direct sunlight and wear a hat on hot days anyway, but in 2024 https://theheartattackdiet.substack.com/p/sunburn-test I tried really really hard to get burned in a similar heatwave (although higher up, so less hot but more UV). And I couldn’t. I just smoothly went brown.

And one thing that almost everyone who strictly avoids PUFAs reports is that after about six months, they become almost completely immune to the sun.

But the other day I cycled around without a shirt on in the sun for about an hour and later on I noticed that the skin on my chest had gone red (with a white stripe where the strings of my nerd-bag had been). And it felt slightly uncomfortable and I didn’t want the sun shining on it any more.

That’s (minor) damage, not tanning.

So I’m really quite stunned by that. I absolutely didn’t predict it, and wouldn’t have. But it does rhyme nicely with yo-yos->PUFA-release->PUFA-symptoms, doesn’t it?

Commentary

I think I’m going to call this a thumping success. Slightly better than expected weight loss, no keto flu, tiredness much improved if not the extreme clarity (or just “feeling normal” as I would have put it pre-CFS) of ex150ish.

Unfortunately I am in the middle of the fens, a long way from sources of supplies, and it is far too hot (35C yesterday!) for the eight-mile cycle that I’d have to do to buy more fruit.

I ate my last grapefruit today, but I have plenty of stew left and there’s a bit of sour cream still in the fridge which is hopefully still edible, and also minced 80/20 beef and butter.

So I’m going to just carry on eating what I have, which makes today the start of ex150ish-no-double-cream-sccf-brief-involuntary (using sccf to stand for sour-cream and crème-fraîche going forward because I am sick of typing that). There are plenty of carbs in the forbidden cupboard, honey and flour and sugar I think. I am not tempted at all. I will break into them if I actually start to starve before I’m next near shops.

You can tell I’m feeling better because I have been programming for fun, and amongst the several things I’ve done is to add labels to the graph so we can tell what the coloured bars mean.

The sunburn thing is freaky. It occurs to me that that means that I must be more PUFA’d than I’ve ever been, poisoned by my own body fat as a result of the huge recent weight yo-yos. And that would nicely explain my feeling that my tiredness has got a lot worse over the last six months, and the fact that the last visit home occasioned a new weight record at a mighty 100.6kg.

But it does not explain why my set-point is apparently somewhere below 97kg. If I’m currently badly PUFA-poisoned, that should have gone up too, presumably to higher than the starting off value of 99kg when I first gave up PUFAs. And yet last time I came home from visiting Mum my appetite disappeared and I lost roughly 3kg spontaneously.

This is very confusing. I notice that I am confused, at least one of the things I believe is fiction. I wonder what’s going on?

Predictions

ex150ish-no-cream-sccf-brief-involuntary will probably last a few days. I expect to go into deep ketosis since I’m probably already largely out of glycogen, so I expect proper mental clarity and inexhaustible energy but also the weird “two fuels” effect if I think too hard for too long.

I don’t expect to lose any water-weight, it’s probably all gone anyway now, but I do expect to keep losing fat at around 1kg/week. So if I last a week call it 92.8kg?

I haven’t taken any thyroid for nine days now and I’m still overheating in the hot weather. Blood levels by my decay calculations are now down to about 1/1000th of the original amount! No thyroid symptoms except the tiredness and overheating, which could be hypermetabolism symptoms even. I guess I predict that all that will continue.

I also predict further sunburns if I’m my usual careless self about sun exposure. Though I might take more care not to be exposed to the direct sun, and also develop a deeper tan, so maybe not.

12/06/26 97.4 36.7 0.004 0.004 144/78/48

11/06/26 96.9 36.85 0.006 0.006 134/76/58

10/06/26 97 0.002 0.002 130/83/55

09/06/26 97.3 0.004 0.004

08/06/26 98.2 36.5 0.002 0.002 147/89/48

07/06/26 97.1 36.9 0.002 0.002 133/73/53

06/06/26 97.3 36.5 0.002 0.002 152/91/48

Predictions from Last Post

I think if the PUFA-release idea is true, then my weight should probably stop falling about now, at 97kg, a little higher than it was last time, but then since I’m not losing weight any more, I won’t be releasing much in the way of PUFA, so the tiredness will start to clear up, and also my lipostat will start to work better, so I’ll start losing weight again, which will of course release more PUFAs.

On the other hand if it’s not true, then I think I’d still expect to carry on losing weight until I hit 96kg or so, a bit lower than it was last summer when I was stable at 97kg, while the fatigue just clears up on its own.

So either way I’m expecting to lose more weight and get less tired as time goes on, and I can’t really see any way to distinguish those two cases.

I would be surprised if I just hit a plateau at 97kg and carried on like that for any significant length of time, or started to go back up, or if the tiredness just continued and didn’t improve.

The responsible thing to do would be nothing, and see what happens with no intervention.

But after a whole month of not doing anything, I am really getting quite tempted by the idea of trying a bout of ex150ish anyway, just to be done with the fatigue. If I do that, then I’d expect to as usual lose 1.5kg of water weight very fast, stop being tired and then lose fat at the usual 1kg/week rate for as long as I keep it up. That actually sounds pretty good so I might do that instead. I’ll see how I feel when I next run out of carbs and have to go shopping.

What Actually Happened

Weight seems to have either stopped falling or temporarily plateaued at 97kg, the fatigue does seem to be moderating, but it’s still there, mainly manifesting now as a need to go to bed every day at around 1700, but not actually resulting in sleep, just lying down for a bit and then feeling better an hour later. But also periods of sluggishness randomly at other times.

I guess that’s very slight evidence in favour of PUFA-release being the problem, which I already kind of believe. The responsible thing to do would be nothing, wait and see what happens....

But I’m sick of it. I want my mind back, and ketosis usually restores me to feeling well, so I’m going to try something new.

Sour cream and crème fraîche always seem interchangeable with double cream for me, even though I think they’ve caused trouble for u/exfatloss in the past, but given that you can make sour cream by adding vinegar or lime juice to ordinary double cream, and I’d definitely allow vinegar and lime juice as condiments anyway, I don’t think they affect the ex150 effect for me personally, and I like them more than I like drinking double cream straight, so I’m just going to add them to ex150ish on the basis that they probably won’t make any difference.

But I’m also going to allow myself to eat a piece of fruit (an apple, a grapefruit, a kiwi) every day, and also to have milk in my tea, because that has reduced the carb-cravings I get in the past, while not being enough carbs to take me hugely out of ketosis. I’ll avoid major sources of carbs like bread and potatoes entirely though.

I hope in this way to get the reliable fatigue benefits of ketosis while also being in a state I’d be happier to sustain indefinitely. Not that I actually imagine I will, there are always social reasons to eat normally as well, but if it’s possible that’s interesting information! And secondarily it will mean that I don’t have to throw away any of the excellent organic fruits that occasionally turn up in my weekly veg bag, which would make me sad even though it’s no big deal in the grand scheme of things.

It might also mean that the shock of coming out of ketosis and then going back in is less bad, which might mean that I can have cheat days occasionally rather than having to stick to it strictly or stop doing it entirely, which flexibility would make it more likely that I could just adopt this as a normal way to eat. Fingers crossed.

So ex150ish-sour-cream-crème fraîche-low carbs started on Saturday 13th June when I ate my last potatoes and I’ve been doing it since. (Today is the 16th, but I haven’t typed up my records of the last few days yet…)

Predictions

I expect that this will work pretty much exactly as ex150ish does, so I’ll predict accordingly, except that the “two fuels” thing that I always get (brain occasionally stops working while body still full of energy) strikes me as something that might only be a feature of deep keto, and also it might not entirely kill the fatigue if that’s coming from ‘glycolysis is blocked’, but I want to see.

And also who knows what the ex150 weight loss effect actually is, even tiny amounts of carbs might affect it.

So, I predict with some confidence but not the high confidence I’d usually have:

Mild headaches on ketosis entry. But it’s usually pretty smooth if I remember to take electrolytes for the first few days. Note to self, remember to take electrolytes!

Non-existent appetite, rapid weight loss

Excellent mental clarity, and the “two fuels” problem where I can get my mind tired while still having plenty of physical energy.

I expect to lose 1.5 kg of water-weight immediately as I shed my glycogen reserves, then to lose body fat at around 1kg per week.

Current average is 97.3 kg, so in one week’s time I expect to be 94.8 kg, and in two weeks time 93.8kg, and then I expect to bounce back up by 1.5kg over two or three days whenever I add significant carbs back in.

If it doesn’t cause any weight loss at all I’ll be quite surprised, but I won’t be too surprised if it doesn’t work as well as usual, or do the same things but slower, and if it’s obviously not working at all then I’ll probably cut the remaining carbs.

04/06/26 97.8 36.6 0.005 0.005 142/84/50

03/06/26 97 36.5 0.004 0.004 129/78/55

02/06/26 96.7 36.5 0.002 0.002 121/77/56

01/06/26 96.7 36.95 0 0 126/82/60

31/05/26 96.6 36.2 0.002 0.002 140/86/50

30/05/26 96.2 36.65 0 0

29/05/26 95.9 0 0

28/05/26 96.4 0 0 137/82/52

27/05/26 97.3 36.6 0.004 0.004

26/05/26 98 0 0 149/85/58

25/05/26 98 0 0 142/88/51

24/05/26 97.8 0 0 142/88/54

23/05/26 97.4 36.7 0 0

22/05/26 98.2 36.4 0.006 0.006 130/77/60

21/05/26 97.5 36.8 0.006 0.006 132/81/53

20/05/26 98.6 36.4 0.01 0.01 123/73/43

19/05/26 97.8 36.5 0.007 0.007 138/79/49

18/05/26 97.1 36.7 0.005 0.005 126/78/51

17/05/26 97 36.9 0.007 0.007 133/83/55

16/05/26 97.1 36.9 0.005 0.005 136/84/53

15/05/26 98.9 36.9 0.006 0.006 131/78/58

14/05/26 97.4 36.9 0.006 0.006 129/84/59

13/05/26 97.6 0.006 0.006 129/81/53

12/05/26 36.9 0.006 0.006 141/83/53

11/05/26 98.5 36.75 0.003 0.003 141/83/53

10/05/26 99.1 36.8 0.003 0.003 138/79/51

09/05/26 98.6 37.1 0 0 141/84/55

08/05/26 99.8 36.7 0.006 0.006

07/05/26 98.3 36.8 0.003 0.003 141/80/57

06/05/26 99.1 36.8 0.006 0.006

05/05/26 100.3 36.7 0 0

Predictions From the Last Post

Once I’m back in Cambridge and in control of my own diet again:

I predict that my appetite will collapse, I’ll lose all interest in food and my weight will start to fall at around 1kg/week.

At that point I’ll be living on my own considerable body fat, which is still full of PUFAs.

I predict that that will make me feel unwell in various ways, most notably a remarkable increase in fatigue.

I predict that I’ll start suffering from hypometabolism symptoms again and need to take small amounts of thyroid again to make them go away.

If the fatigue is really unpleasant, then I might try going into ketosis (which reliably gets rid of the fatigue) and see if that helps.

Otherwise I’m just going to ‘take my hands off the controls’ and see what happens next.

I imagine that the weight loss will continue until I get down to about 96kg, which is where things seemed to stabilise last time.

What Actually Happened

All of that pretty much bang on, almost immediately I got back my appetite disappeared and since then I’ve been losing weight at just less than a kilo a week. Seven day average has gone from 100.65kg to 97kg over the last month, which is about as fast as you ever want to lose weight. But the last few days it’s felt like my appetite has come back, so I may be approaching a stable state at 97kg, but time will tell, there was a previous little plateau so I’m going to wait and see.

The first week back I was about as tired as I’ve been since I first discovered that thyroid would fix my fatigue. It’s more a question of ‘I need to sleep a couple of hours in the afternoon most days’ than ‘full-blown chronic fatigue syndrome’. I never did decide that it was bad enough to go into ketosis, mainly because I’ve been curious as to what would happen if I just left my hands off the controls. The fatigue does seem to be getting better as the weeks go by. I’m still a bit generally sluggish, but although three times this week I’ve felt tired enough to try going to bed, I haven’t actually slept during the day this week at all.

I did start to get hypometabolism symptoms, and started taking tiny amounts of thyroid again, and the symptoms went away, and then the weather suddenly got a lot hotter and I started overheating, so I dropped the dose further.

I’m now taking 1/500th of the original dose, which is such a tiny amount it’s difficult to measure, and I can’t really believe it’s doing much, or say whether I’m hyper- or hypo-metabolic at the moment. I don’t have any symptoms except the tiredness itself.

Waking temperatures are about normal, but sometimes a bit high. And the weather can’t decide whether it’s going to be hot or cold at the moment, so it’s all very confusing.

Predictions

I think if the PUFA-release idea is true, then my weight should probably stop falling about now, at 97kg, a little higher than it was last time, but then since I’m not losing weight any more, I won’t be releasing much in the way of PUFA, so the tiredness will start to clear up, and also my lipostat will start to work better, so I’ll start losing weight again, which will of course release more PUFAs.

On the other hand if it’s not true, then I think I’d still expect to carry on losing weight until I hit 96kg or so, a bit lower than it was last summer when I was stable at 97kg, while the fatigue just clears up on its own.

So either way I’m expecting to lose more weight and get less tired as time goes on, and I can’t really see any way to distinguish those two cases.

I would be surprised if I just hit a plateau at 97kg and carried on like that for any significant length of time, or started to go back up, or if the tiredness just continued and didn’t improve.

The responsible thing to do would be nothing, and see what happens with no intervention.

But after a whole month of not doing anything, I am really getting quite tempted by the idea of trying a bout of ex150ish anyway, just to be done with the fatigue. If I do that, then I’d expect to as usual lose 1.5kg of water weight very fast, stop being tired and then lose fat at the usual 1kg/week rate for as long as I keep it up. That actually sounds pretty good so I might do that instead. I’ll see how I feel when I next run out of carbs and have to go shopping.

Sorry! That’s really not much of a plan.

05/05/26 100.3 36.7 0 0

04/05/26 100.5 36.8 0.005 0.005

03/05/26 101 36.7 0 0

02/05/26 101.2 0 0

01/05/26 100.1 36.8 0 0

30/04/26 100.4 36.75 0 0

29/04/26 100.2 36.7 0 0

28/04/26 100.9 36.75 0 0

27/04/26 100.8 36.6 0 0

26/04/26 100.7 36.6 0.005 0.005

25/04/26 100.3 36.85 0 0

24/04/26 100.3 36.8 0 0

23/04/26 100.2 36.6 0.01 0.01

22/04/26 99.7 36.7 0.005 0.005

21/04/26 100.2 36.8 0 0

20/04/26 99.7 36.8 0 0

19/04/26 99 36.85 0 0

18/04/26 99 36.85 0 0

Predictions From the Last Post (Edited for clarity)

For the last two weeks I’ve been starving hungry and I’ve eaten a truly enormous amount.

My weight has gone up like a moonshot. Apparently linearly.

Every day for the last sixteen days I’ve gone for a walk and come home tired, and most days I’ve gone for a lie down, but I’ve only actually gone to sleep a couple of times. Most days I just lie down for half an hour and then feel fine. At all other times I’ve been quite lively and bouncy, not much trace of fatigue except immediately after walks.

I’ve often been too hot and my waking temperatures have consistently been higher than 36.7C.

Often eating makes me break into sweat, which is not at all normal.

I’ve dropped my thyroid dose in an attempt to control this, and it seems to have helped with the tiredness as well as the overheating. No obvious hypometabolism symptoms so far.

I predict that this all continues until I go back to Cambridge. So I expect to set a new all-time high weight record some time next week!

What Actually Happened

I carried on being hungry, but the effect lessened and the weight graph as a whole for the last five weeks looks like an exponential decay. I can’t tell by looking at the graph whether I actually reached a plateau or whether there was more to come. But my current seven-day average is 100.6kg which is indeed a new all-time high! That’s a BMI of 31.82, class I obesity.

My appetite is back to normal, no strange hunger pangs at weird times, and my poor Mum is wondering why I’m suddenly eating about half as much as I was at first. A crumble went uneaten and has had to be thrown away. A jar of my favourite sulphite-free Maraschino cherries is only half-finished. There is, however, no ice-cream left, I ate the last pot a couple of days ago.

Five weeks ago I was around 94kg, not in ketosis, and perfectly happy at BMI 29.7 which for me is about 9kg overweight but not really a problem.

I’m now about 16kg overweight, and I look it. I’m disgusted by my own body, there are great rolls of fat on my belly and even though my special very large trousers still have plenty of room in them, sitting down is rather uncomfortable even if I undo my belt.

I can believe that my actual ‘set point under maternal conditions’ could be 100.6kg, and I’m now weight-stable, or there might actually be more to come.

I’ve basically been forced off the thyroid. Even the tiniest amount now seems to be making me overheat so I’m just not taking it any more, and by my calculations the amount still in my blood is about 1/700th of what was once my daily dose.

Fatigue-wise nothing much happened, still mostly fairly lively, but still getting really tired after going for a walk and needing to lie down, then recovering quickly.

I found a stash of placebos in a cupboard and have been taking ribose for about two weeks, which didn’t seem to make much difference.

For the last week or so I’ve also been taking vitamin B12 and floradix tablets (iron and various B vitamins in small quantities). They did seem to help a bit, but not dramatically. So I think they really are placebos, but I’m going to keep taking the B12 for a bit just in case it does help.

At no point did I try the obvious experiment of not going for a walk and seeing what happened, the weather’s been great and I like my walks. I get a bit stir crazy if I don’t go out during the day. So it may actually be that I’ve been basically fine but just no longer have the energy for an hour and a half of gentle exercise without needing to recover afterwards.

Today I am on the train back home, so I won’t find out anything more about weight presumably. At 1600 I felt suddenly tired and lethargic, and that state carried on for about half an hour and now I feel fine again. So it’s not just the walking making me feel tired in the afternoons.1

Conclusions

I’m not reading too much into being off the thyroid, this has happened twice before when visiting home and both times eventually the symptoms have come back and I’ve started needing it again. But it’s definitely a positive sign that something about avoiding PUFAs and sulphites is fixing my long-time curse of hypometabolism.

Weight-wise I’m perplexed. The heaviest I’ve ever previously been was a seven-day average of 99kg, and that was back in 2023, almost exactly three years ago. At that point my stable weight was rising at around 1kg/quarter, and had been for a year and a half. I’d just come back from visiting my Mum, and so I imagine that I was eating roughly what I’ve been eating for the last few weeks. And I also imagine that that was a real equilibrium weight, I don’t ever remember trying not to eat when I was hungry.

And that was the point I realised that I was still eating loads of PUFA in the form of peanut butter. When I gave that up I was finally eating a PUFA-free diet, and my weight’s never been that high since.

Since then visiting Mum has always caused me to gain weight, but the last two visits home have been absolutely spectacular, as if the effect has been supercharged and the ‘equilibrium under maternal conditions’ is suddenly much higher than it ever has been before.

And the only explanation I can come up with is psychological. Last year I came up with the idea that yo-yo dieting might be good, actually, and since then I’ve been happily watching myself balloon on the basis that gaining weight is diluting the PUFA content of my body fat.

I don’t like psychological explanations for things, not because psychology is irrelevant, but because you can explain absolutely anything that way.

And it doesn’t feel right. On previous visits home I wasn’t trying to eat less than I wanted or anything, I’ve always believed that that’s a mug’s game. You’ll be hungry until you hit the equilibrium your body is trying to reach, and there’s no point in fighting it. Trying to eat less is just fiddling your own results and leads to false conclusions. And these last two times it’s not like I’ve been deliberately over-eating, I ate whenever I felt peckish and not otherwise.

So I am as usual utterly confused. Something about this PUFA-free, sulphite-free diet has seemed to have been slowly lowering my equilibrium weight over the last three years, and yet suddenly I’ve found that this ‘maternal equilibrium’ is higher than it used to be. And I have no idea what is going on.

Predictions

Once I’m back in Cambridge and in control of my own diet again:

I predict that my appetite will collapse, I’ll lose all interest in food and my weight will start to fall at around 1kg/week.

At that point I’ll be living on my own considerable body fat, which is still full of PUFAs.

I predict that that will make me feel unwell in various ways, most notably a remarkable increase in fatigue.

I predict that I’ll start suffering from hypometabolism symptoms again and need to take small amounts of thyroid again to make them go away.

If the fatigue is really unpleasant, then I might try going into ketosis (which reliably gets rid of the fatigue) and see if that helps.

Otherwise I’m just going to ‘take my hands off the controls’ and see what happens next.

I imagine that the weight loss will continue until I get down to about 96kg, which is where things seemed to stabilise last time.

18/04/26 99 36.85 0

17/04/26 99.8 36.75 0 0

16/04/26 99.2 36.75 0.005 0.005

15/04/26 99.8 36.8 0 0

14/04/26 99.3 36.85 0 0

13/04/26 36.7 0.01 0.01

12/04/26 97.9 36.7 0.005 0.005

11/04/26 97.4 36.75 0.005 0.005

10/04/26 97.9 36.9 0.005 0.005

09/04/26 97.4 36.7 0.006 0.006

08/04/26 97.7 36.85 0.008 0.008

07/04/26 97.7 36.75 0.01 0.01

06/04/26 97 36.8 0.005 0.005

05/04/26 96.5 36.4 0.014 0.014

04/04/26 96.1 36.4 0.008 0.008

03/04/26 95.5 37.1 0.01 0.01

02/04/26 96.1 36.7 0.012 0.012

01/04/26 93.4 36.63 0.008 0.008 137/77/48

31/03/26 93.7 36.95 0.01 0.01 131/82/52

30/03/26 95.1 36.39 0.01 0.01 135/82/52

29/03/26 95 36.7 0.01 0.01 129/82/52

28/03/26 95 36.7 0.014 0.014 143/84/50

27/03/26 95.2 36.65 0.016 0.016 121/74/49

26/03/26 94.1 36.84 0 0 137/83/55

25/03/26 94.5 36.66 0 0 133/85/52

24/03/26 93.5 36.64 0.008 0.008 137/83/53

Predictions from the last post

[confused rambling...]

If ex150ish+sour cream+crème-fraîche+fruit+biscuits+booze+kebabs+potatoes+ice-cream is also an effective weight loss diet despite not being ketogenic at all, then I should recarb by 1.5kg in total up to maybe 94.5kg and then lose weight slowly over the next week.

What actually happened

I didn’t even have the discipline to do the biscuits and booze and kebabs bit, so let’s call the first week ex150ish+sour cream+crème-fraîche+fruit+potatoes+ice-cream

I did remember to eat lots of chips and baked potatoes and a couple of buckets of ice-cream.

Three times that week I was tired enough in the afternoon to try going to bed, but then found that I couldn’t sleep and got up again feeling fine. Otherwise I was fine.

Weight-wise I can’t really say what happened here, but eyeballing the graph it does actually seem possible to believe that I recarbed while losing some fat that week.

At any rate my weight on the 1st April was 93.4kg, ever so slightly lower than it had been at the start of the week when I was probably in ketosis. Go figure.

More predictions from the last post

At which point I’m going to go and visit Mum for Easter and probably stay for a while. And my weight will shoot back up crazy fast to 99kg or so for no reason I bloody understand.

[forgot to say anything about thyroid, but probably would have predicted that it would fall since it often does when visiting Mum ]

What actually happened

At that point I got the train home to visit Mum. I actually felt quite sleepy on the train, but couldn’t sleep and recovered after about half an hour.

I was greeted the minute I walked in the door by a huge piece of roast beef and a pile of chips, which I wolfed.

And woke up the following morning weighing 96.1kg. That seems a bit unlikely, maybe the scales at home have become (really badly) uncalibrated? Not sure how to tell.

Since then almost everything I’ve eaten has come with a vast amount of protein in it. Endless beef, endless cheese. I’m not complaining, I love that stuff. No PUFAs, no sulphites.

For the last two weeks I’ve been starving hungry and I’ve eaten a truly enormous amount. One day I had three consecutive dinners, one of curry and rice because the chips weren’t ready yet and I was too hungry to wait for them, two of curry and chips, and then two hours later I was hungry enough to raid the fridge and eat half a kilo of ice-cream for pudding.

My weight has gone up like a moonshot. Apparently linearly. There was a point where I thought it might have stabilized at 97.5kg, but that doesn’t show up in the seven day average, which is currently at 99.1kg and presumably still rising. That’s about a kilogram every four days(!)

It just appears to be a law of nature that visiting Mum causes me to become so hungry that my weight rises more rapidly than I would believe possible. No idea why except maybe it’s to do with excess protein?

Every day for the last sixteen days I’ve gone for a walk to the pub in Stannington, had a coffee and read a book and then come back, about three miles in total but very up and down because this is the Pennines and there are no flat bits.

Every day I’ve come home tired and most days I’ve gone for a lie down, but I’ve only actually gone to sleep a couple of times. Most days I just lie down for half an hour and then feel fine. At all other times I’ve been quite lively and bouncy, not much trace of fatigue except immediately after walks.

I’ve often been too hot and my waking temperatures have consistently been higher than 36.7C.

Often eating makes me break into sweat, which is not at all normal.

I’ve dropped my thyroid dose in an attempt to control this, and it seems to have helped with the tiredness as well as the overheating. No obvious hypometabolism symptoms so far.

I can just about believe that the enormous overeating means that I’ve been burning less body fat than usual and that that’s reduced pernicious PUFA-effects and caused me to run hot?

Predictions

This all continues until I go back to Cambridge. So I expect to set a new all-time high weight record some time next week!

When I get back and just start eating the sorts of things I usually eat, I’ll lose my appetite and start losing weight fairly rapidly as a result. And I’ll also feel really tired and have to start taking thyroid again because I’ll start to release stored body fat with PUFAs in it.

It occurs to me that it might be an idea to go straight into ketosis when I get back, since that usually means no tiredness and might make the weight loss less unpleasant. But I’ll see how I feel.

At any rate, another big yo-yo seems in the bag.

24/03/26 93.5 36.64 0.008 0.008 137/83/53

23/03/26 93.5 36.9 0.01 0.01 117/74/53

22/03/26 94.1 36.43 0.01 0.01 117/75/53

21/03/26 93.7 36.81 0.006 0.006 137/82/61

20/03/26 94.8 36.6 0.006 0.006 126/85/52

19/03/26 94.2 36.83 0.006 0.006 132/81/64

18/03/26 94.2 36.61 0.014 0.014 130/75/54

17/03/26 93.9 36.66 0.006 0.006 124/77/57

16/03/26 93.5 36.95 0.014 0.014 135/83/55

15/03/26 94.2 36.74 0.01 0.01 156/96/50

14/03/26 95.1 36.63 0 0 139/81/52

13/03/26 36.84 0 0

12/03/26 95.6 0 0

11/03/26 95.2 36.96 0 0 154/90/48

10/03/26 95.7 36.81 0 0 162/85/49

Predictions From the Last Post

ex150ish has worked for me ten times out of eleven now, and at 96kg I’m definitely in the regime where it’s worked before, so Laplace tells me I should now have 11:2 odds or 84% confidence that it will work again

So I predict (at 84% confidence):

Mild headaches on ketosis entry. But it’s usually pretty smooth if I remember to take electrolytes for the first few days. Note to self, remember to take electrolytes!

Non-existent appetite, rapid weight loss, excellent mental clarity, and the “two fuels” problem where I can get my mind tired while still having plenty of physical energy. If any of these things don’t happen I’ll be surprised.

I expect to lose 1.5 kg of water-weight immediately as I shed my glycogen reserves, then to lose body fat at around 1kg per week.

Current average is 96.1 kg, so in one week’s time I expect to be 93.6 kg, and in two weeks time 92.6kg, and then I expect to bounce back up by 1.5kg over two or three days whenever I add significant carbs back in.

What Actually Happened

In retrospect my major failure was predicting that I would actually do ex150ish for two weeks.

In fact as soon as I was standing in the milk and cream aisle in the supermarket I decided that I would buy a load of sour cream and crème fraîche which looked really appetising as well as a couple of big pots of double cream, which looked kind of bland and horrible. And then I decided that since I wasn’t doing the real thing anyway I might as well get some fruit too.

And I was thinking that this probably wouldn’t make much difference, but also that I couldn’t really count it as an ex150ish fail if it didn’t work.

And everything went as expected until Thursday night and choir when there was tea and biscuits and the kind persons doing the tea had bought all-butter shortbread biscuits cos they know I like them and they’re quite expensive so I ate a load. I think that was a bit of a recarb because I felt a bit woozy and hot immediately afterwards.

And then I got drunk and as I was cycling home I went past a known-good kebab shop, and I thought ‘Oooh I really fancy a kebab’, but I bravely cycled past and it was when I was thinking ‘I really really fancy a kebab’ for the third or fourth time and was a good couple of hundred yards away that I thought ‘Hang on, you have got CRAVINGS and you are using WILLPOWER to ignore them’, and so I went back and had a lamb doner wrap. Loads of lamb and salad and probably a bit of seed oil in the dressings and a very thin bread wrap around it all, it was delicious.

And then everything went fine until the following Thursday when all those things happened again.

Apart from that I was as GOOD as GOLD except that there were many excellent reasons to get mildly drunk during the last two weeks and totting it all up I think I had about half a bottle of scotch in total.

Anyway it seems to have kind of worked in spite of all that, but not as well as I was expecting.

Mild headaches on ketosis entry. But it’s usually pretty smooth if I remember to take electrolytes for the first few days. Note to self, remember to take electrolytes!

Did take electrolytes, got one headache which was bad enough to take one ibuprofen and one paracetamol to get rid of. Also a couple of ‘ghost headaches’, where you kind of feel like you might be about to get a headache but it doesn’t actually happen.

Non-existent appetite, rapid weight loss, excellent mental clarity, and the “two fuels” problem where I can get my mind tired while still having plenty of physical energy. If any of these things don’t happen I’ll be surprised.

Appetite was noticeably low, but not totally vanished, there was weight loss but not as rapid as usual, mental clarity was improved but not perfect, I found myself feeling like I needed a nap most afternoons and then not sleeping but getting up again feeling refreshed. And some days no tiredness at all. I definitely got the two fuels problem at at least three points, perfectly awake but somehow run out of brain after a day’s hard thinking and talking.

I expect to lose 1.5 kg of water-weight immediately as I shed my glycogen reserves, then to lose body fat at around 1kg per week.

Definitely got the water-weight drop, but seem to have only managed 1kg of fat loss over the whole fortnight, so half as fast as usual

Current average is 96.1 kg, so in one week’s time I expect to be 93.6 kg, and in two weeks time 92.6kg, and then I expect to bounce back up by 1.5kg over two or three days whenever I add significant carbs back in.

Was 94.2 after a week, and 93.5 at the end of two weeks.

At the end of the two weeks I was like ‘Recarb!’ and made a load of chips (french fries US friends) shallow fried in butter. Delicious, and immediately afterwards I felt suddenly sleepy and went to bed and slept for two hours before waking up fine. Next morning my weight had jumped a kilo presumably from partially restoring my glycogen reserve. The tiredness has got slightly worse again, but I’m still feeling pretty good.

I forgot to make any predictions about thyroid dose, but given that I was thyrotoxic a couple of weeks ago I would have predicted that I would stop taking it entirely.

However although I took the dose down to zero at one point, I then started to get slow-metabolism symptoms and put it back up again, and I’ve ended up roughly where I have been since last November.

I continue to be surprised by this. I’m taking a minute amount of thyroid compared to what I used to. Over the last three years whatever problem I had seems to have largely fixed itself, I’ve no idea why apart from ‘seed oilz bad’, but it seems that I still need a tiny bit (practically homeopathic, 1/100th of what I used to take) to run properly, and that’s been stable for months now. This is just confusing. I continue to predict that as the weather warms up I’ll stop needing it completely, but I keep predicting this and I keep being wrong. I notice that I am confused. One of the things I believe is fiction. And yet I keep believing it anyway. Sigh.

Being human is hard. I wish I had a real mind that just worked instead of this crappy bodge-job full of kludges and lost purposes. I want to be Lawful Good and also to update smoothly and well on evidence.

I continue to predict that I will eventually stop needing the thyroid altogether, but now with quite low confidence, and I also predict that after a number of months of this not happening I will eventually give up on the idea. Which really will leave me confused. What the hell effect can fix 99% of a problem but leave the work not quite done at the end?

Anyway I conclude that ex150ish+sour cream+crème fraîche+fruit+biscuits+booze+kebabs is indeed a successful weight loss diet, and caused ketosis but probably not as deep as ex150ish would do.

But it’s only about half as effective as ex150ish proper and given that it’s roughly as much trouble there doesn’t seem much point to it.

On the other hand, it does seem more sustainable. I’m not bored of it yet, so what I think I’ll do for the next week is just add chips and ice-cream to it and see what happens.

I have no real prediction here, but there’s a range of options.

Predictions (Bewildered)

If it’s true that PUFA depletion is important, then I should have a ‘free-feeding equilibrium’ somewhere below 94.75kg due to my recent big yo-yo, and definitely below 97kg, which was my last definite equilibrium, since which there have been two big yo-yos.

If it’s not true that PUFA depletion matters, but something else about my no-PUFA, no-sulphites diet is lowering my equilibrium by 1kg/year, then my ‘free-feeding equilibrium’ should be around 96kg now.

If ex150ish+sour cream+crème-fraîche+fruit+biscuits+booze+kebabs+potatoes+ice-cream is also an effective weight loss diet despite not being ketogenic at all, then I should recarb by 1.5kg in total up to maybe 94.5kg and then lose weight slowly over the next week.

If it isn’t, then I should head back up towards my ‘free living equilibrium’ over the next week.

At which point I’m going to go and visit Mum for Easter and probably stay for a while. And my weight will shoot back up crazy fast to 99kg or so for no reason I bloody understand.

The Blessings of the Risen Lord upon Y’All. Gaudeamus!

10/03/26 95.7 36.81 0 0 162/85/49

09/03/26 96.1 36.71 0.01 0.01 139/84/51

08/03/26 96.8 0 0

07/03/26 95.3 36.78 0.01 0.01 148/88/44

06/03/26 96.7 0.01 0.01 119/32/55

05/03/26 96.3 36.6 0.01 0.01 137/80/46

04/03/26 96.2 0.01 0.01 146/90/48

03/03/26 97.1 0 133/81/59

02/03/26 95.2 36.93 0.014 0.014 131/77/51

01/03/26 95.3 36.59 0.014 0.014 145/80/45

28/02/26 96.4 36.77 0.014 0.014 128/74/47

27/02/26 96.7 36.68 0.014 0.014 130/79/49

26/02/26 95.2 36.84 0.014 0.014 128/78/55

Predictions from the Last Post

Weight continues to fall, at a bit less than half-a-kilo a week, slowing as I approach a new equilibrium which is somewhere below 94.75kg.

Fatigue improves. Thyroid dose falls.

What Actually Happened

Seven day average weight rose 0.1kg over the last ten days. Looks to me like I found a new equilibrium at around 96kg and it’s just noise now.

Fatigue totally gone, records show a mixture of fine all day, unusually energetic, too hot, and hypomania (which is the state just short of proper mania where you’re really enthusastic about things and your to do list just disappears). Occasionally feeling tired and going to bed but not able to sleep. Also my morning blood pressure readings are spiking. I am clearly thyrotoxic.

I am dropping thyroid doses to try to control this and avoid going into a real manic state where I start getting revelations of total enlightenment, blowing my entire bank account on sure thing stock market bets, starting fights and proclaiming myself the new Messiah.

Provisional Updating of Beliefs

So on the face of it, getting the PUFAs out of my body fat isn’t fixing my obesity problem.

But something is. This new equilibrium is about 1kg lower than my last equilibrium this time last year which was 97kg. Which is to say that the problem is getting better at about 1kg/year like it has been doing since I started this. That’s got to be something to do with what I’m eating, hasn’t it?

But if it was PUFAs in my body fat, then my recent two huge weight yo-yos should have made a difference. I notice that I am confused. At least one of the things I believe is wrong.

Even more weirdly, last time I came back from visiting my parents, my weight was 96kg and it fell freely to about 95kg before I started messing. So it looks like the problem has actually got worse over the last few months. This new equilibrium is higher than the one last September.

The thing that looks most likely to be wrong is the belief that getting rid of stored PUFA should fix obesity. I’m pretty sure that I’ve got rid of a fair bit of stored PUFA recently.

Another belief that must be questioned is the very existence of a lipostat, but I really can’t see how that could not be true. And what I’ve seen is consistent with it, it’s just that the set-point has moved in the opposite direction to how I expected.

And another is that weight yo-yoing while eating very little PUFA reduces the amount of stored PUFA, but again, I can’t see how that might not be true.

I provisionally abandon the belief that obesity is caused by stored PUFAs. I now have low confidence that that is true. I reserve the right to go back to that belief if it looks true later, but for now I don’t believe it.

But

Over the second half of January and February I lost about 3kg. That’s about 537kcal/day of energy coming from my own body fat, which is presumably heavily contaminated with PUFA, probably around 10% linoleic acid.

That coincided with a period of fatigue as bad as I can remember for years.

That’s probably the pernicious effect of having loads of linoleic acid floating around my system.

And maybe, if LA is the thing breaking my lipostat, all that LA has made it temporarily worse than it would be in a true equilibrium state.

So I can weasel out of the paradox. But I am weaselling. I didn’t predict this and I notice that I am confused.

The epistemologically responsible thing to do here would be to wait a bit, and see if that equilibrium starts to drop, and ends up at around 94kg like I was expecting.

But

Fuck that. I am longing for a couple of weeks of ketosis and the associated energy and clarity. And I am probably going to go and visit Mum again quite soon.

I want the LA out of my body fat for all sorts of reasons that are not obesity, and yo-yoing still looks like a good way of doing that.

So I still want to lose some weight before going home, in order to take maximum advantage of the inevitable massive weight gain associated, for unknown reasons, with going to visit Mum.

So ex150ish-11 starts today, all carbs have been eaten already so for the next couple of weeks or so I’ll buy only beef and cream and non-carby vegetables. Maybe a bit of fruit if some turns up in a veg bag, that doesn’t seem to disturb things much.

Predictions

ex150ish has worked for me ten times out of eleven now, and at 96kg I’m definitely in the regime where it’s worked before, so Laplace tells me I should now have 11:2 odds or 84% confidence that it will work again

So I predict (at 84% confidence):

Mild headaches on ketosis entry. But it’s usually pretty smooth if I remember to take electrolytes for the first few days. Note to self, remember to take electrolytes!

Non-existent appetite, rapid weight loss, excellent mental clarity, and the “two fuels” problem where I can get my mind tired while still having plenty of physical energy. If any of these things don’t happen I’ll be surprised.

I expect to lose 1.5 kg of water-weight immediately as I shed my glycogen reserves, then to lose body fat at around 1kg per week.

Current average is 96.1 kg, so in one week’s time I expect to be 93.6 kg, and in two weeks time 92.6kg, and then I expect to bounce back up by 1.5kg over two or three days whenever I add significant carbs back in.

25/02/26 96.4 36.39 0.014 0.014 118/72/49

24/02/26 95.7 36.7 0.014 0.014 135/84/61

23/02/26 95.7 36.7 0.014 0.014 124/79/59

22/02/26 95.3 36.5 0.014 0.014 130/79/66

21/02/26 95.3 36.7 0.014 0.014 133/79/52

20/02/26 95.8 36.64 0.014 0.014 136/83/54

19/02/26 97.1 36.6 0.012 0.012 129/79/50

18/02/26 97.6 36.66 0.014 0.014 148/85/51

17/02/26 96 36.86 0.015 0.015

16/02/26 95.9 36.62 0.012 0.012 124/76/51

15/02/26 95.2 36.66 0.016 0.016 132/81/44

14/02/26 96.7 36.75 0.012 0.012 132/86/52

13/02/26 97.3 0.014 0.014

12/02/26 96.6 36.65 0.013 0.013 130/83/58

11/02/26 96.1 36.81 0.012 0.012 137/88/57

10/02/26 95.9 36.71 0.012 0.012 130/83/48

09/02/26 95.2 36.44 0.01 0.01 130/80/60

Predictions from the Last Post

Last time I came back from Mum’s I was around 96kg and my weight fell to 94.75kg under its own power before I started messing. Now I look at it there was even a little dead-cat bounce back then, although less noticeable. That was last September and the situation should have improved since then, especially since there’s been a massive weight yo-yo since then.

So I expect that to happen again at least, and if there’s anything to the yo-yo theory it should go a bit lower than that this time. The rate of weight loss should drop a bit as I approach a new lower equilibrium, at which point I’ll probably switch over to ex150ish or some variant and see how low I can get.

Fatigue-wise I guess I expect that this is some sort of transient effect of God-knows-what and I’ll recover and feel well again soon, but since I have no idea what’s causing it I’ve got no idea whether that’s true or how fast it will happen. If it doesn’t get better on its own I might start doing the full keto ex150ish just to see if that helps, because I usually feel great in ketosis.

Results

So when I set out to write this post I figured I’d dropped a load of weight and then plateaued at 95kg, indeed my weight today is 95.2kg, which was the same as my weight on the 9th when I made the last post. And I was going to say, so that looks like it for the yo-yo idea, and so that looks like it for ‘no-PUFAs fixes my weight problem’. Because last September I was about this weight and dropping while eating ad-lib, and now I’m about this weight and stable while eating ad lib, and than means that my equilibrium weight is now higher than it was, and I can’t explain that in terms of my current model of how things work so I am wrong in some important way.

And then I typed up my records and made the new graph and actually it looks like my seven-day average is still falling, now 95.62 as opposed to 96.45 on the 9th, and it looks like I’m currently losing weight at about half-a-kilo a week. Which is actually entirely consistent with with my predictions, weight loss slows as I approach a new equilibrium which is probably somewhere below 94.75kg.

Fatigue-wise things do seem to have got better. Mostly I’m fine, mostly my records say “fine all day”. There have been occasional afternoon naps in the last couple of weeks but they feel tactical as in ‘I have something to do later, I am going to lie down and close my eyes for a while so I have the energy to do it’, rather than ‘Oh God I am shattered and I am going to bed until I feel ok’. Still fatigue, still unusual and a disease I would like to be rid of, but not as bad as it was.

It feels like that’s because I’m taking 4 vitamin B12 pills every morning, and at one point I dropped them for a couple of days and the fatigue got worse so I started taking them again.

But I just don’t believe that. I’m taking an enormous amount of B12 most mornings. You’re very good at holding on to B12, once you fix a deficiency it should be ages before it’s a problem again, and it should come on very slowly.

My actual thyroid dose is slightly higher than it was, 7/500ths of the original dose rather than 5/500ths. That’s mainly because I’m pushing it as high as I can to try to combat the fatigue, but I’m feeling a bit too hot so it will probably have to come back down at some point, and the weather is starting to warm up as winter ends.

Yesterday (25th February) was the first day of the year when it was nicer to sit outside the pub reading in the sun than than to go inside. That’s some sort of record, the earliest I’ve ever done that before was the 28th, but it wasn’t just me, there were loads of people who presumably weren’t in a state of slight thyrotoxicity sitting in the unseasonal sunshine too.

So, ok, played for and got. Both predictions seem to have worked out. Bravo me. At that point I’d planned to do ex150ish for a bit to speed things up and because I still feel a bit fatigued and I am longing for ketosis.

But my ‘You are Fooling Yourself’ alarm is going off quite loudly here. Was I being fooled by noise when I thought I’d plateaued, or am I being fooled by noise now?

So I’m going to carry on eating whatever I happen to fancy and seeing what happens next, so that I can see more clearly what’s going on.

Predictions

Weight continues to fall, at a bit less than half-a-kilo a week, slowing as I approach a new equilibrium which is somewhere below 94.75kg.

Fatigue improves. Thyroid dose falls.

The entire list of significant turning points is this:

keto_water_weight=1.5

readings = [

(”2023-05-22”, 99),

(”2023-09-14”, 92+keto_water_weight),

(”2023-10-13”, 95.46),

(”2023-11-11”, 91.6+keto_water_weight),

(”2024-04-05”, 97.44),

(”2024-05-05”, 95.50),

(”2024-08-28”, 97.16),

(”2024-09-22”, 94.88+keto_water_weight),

(”2024-10-06”, 96.6),

(”2024-11-03”, 93.4+keto_water_weight),

(”2024-12-29”, 96.6),

(”2025-01-14”, 94.07),

(”2025-03-28”, 96.94),

(”2025-07-01”, 92.37),

(”2025-09-15”, 96.2),

(”2025-11-23”, 91.2+keto_water_weight),

(”2026-01-12”, 99.18),

(”2026-02-09”, 96.41),

]

With the last one, which isn’t a turning point, provisional, just the latest seven-day average.

In this graph, green is non-fat mass, red is normal body fat, and yellow is PUFA, with the scale on the right in kg. The black line is the fraction of total fat which is PUFA, scale on the right with some illustrative lines for various populations where we know or can guess the percentage.

You can see that my recent huge weight yo-yo has made a big difference to the (inferred) PUFA fraction. From about 15% to about 12% over a couple of months.

This graph is based on some pretty pessimistic assumptions, PUFA-wise, such as that I started at 25%, that just eating an almost no-PUFA diet doesn’t actually cause depletion in itself1, and that when I lose weight I lose normal fat faster than PUFA2, so that the percentage actually rises.

There is also the rather optimistic assumption that because I’m never doing anything other than eating ad-lib, and so never causing my body to think that resources are scarce and going into starvation-mode, my weight loss periods don’t involve losing significant non-fat mass.

So if the optimistic assumption is true, then my current guess at PUFA making up 11% of body fat is kind of an upper limit on what must have been happening, and I imagine that the true situation is at least slightly better than that.

I infer that I’m probably now below the reported modern British average PUFA content of 12%.

64% of modern British adults are overweight (BMI>25), and 26% of us are obese (BMI>30).

At 95.2kg and 5’10” (~178 cm), my current BMI is:

$ python3 -c ‘print((95.2)/ ((5*12+10)*0.0254)**2)’

30.1143459429776

I’m roughly on the boundary between overweight and obese, although since my ‘happy BMI’ was 27 at my once normal weight of 85kg3, I’m probably not as overweight as my raw weight/height makes it look. I’m not unhappy at 95.2kg, and down at 92kg I stop noticing that I’m fat at all. It got to 93kg before I even realised that I was putting on weight.

So that all looks kind of plausible so far, I guess.

Three years ago my weight was stable at 99kg4, now it seems to be stable somewhere below 95kg5.

My predictions are that short-term I will continue to lose weight ‘naturally’, that is without doing anything in particular to cause that to happen, and that long term, further yo-yos will reduce the amount of PUFA that I’m carrying, and if PUFAs do cause obesity and lack-of-PUFAs can fix it, then that should start to take me back in time, weight-wise. It does so far seem to be doing exactly that.

The next target is modern China’s level of 10% and just below that the level of Americans in the 1970s, who weren’t yet notably fat as I remember, although they were starting to be. Still a long way to go to get down to more natural levels.

08/02/26 36.29 0.01 0.01 127/81/50

07/02/26 96.3 36.86 0.01 0.01 142/77/47

06/02/26 97.3 0.01 0.01

05/02/26 97 36.72 0.014 0.014 135/79/59

04/02/26 96.1 36.65 0.016 0.016 131/81/52

03/02/26 96.6 36.24 0.012 0.012 128/83/45

02/02/26 96.7 36.75 0.01 0.01 136/82/54

01/02/26 97.3 36.82 0.01 0.01 132/76/56

31/01/26 97.7 36.94 0.01 0.01 131/78/59

30/01/26 97.7 0.026 0.026 125/72/53

29/01/26 98.1 36.64 0 0 128/72/50

28/01/26 98.7 36.84 0.01 0.01 117/71/65

27/01/26 97.7 36.8 0.014 0.014 141/81/52

26/01/26 97.6 37.18 0.01 0.01 130/78/57

25/01/26 98.1 0.008 0.008 123/77/52

24/01/26 96.2 36.74 0.019 0.019 127/69/58

23/01/26 98.3 36.6 0.009 0.009 135/76/58

22/01/26 97.2 36.76 0.01 0.01 139/88/52

21/01/26 97.2 36.74 0.008 0.008 132/81/52

20/01/26 97.3 36.92 0.01 0.01 135/81/51

19/01/26 96.4 36.75 0.018 0.018 138/79/51

Predictions from the last post

I expect my lack of appetite to continue, I’m massively visibly overweight and my body appears to have suddenly noticed this. Weight should continue to fall, at least until I get back to my previous free-living equilibrium which seemed to be lower than 95kg. I’ll be really surprised if that doesn’t happen.

I expect to need to reduce my thyroid dose. At the moment I’m torn between ‘I’m too hot’ and ‘I feel really tired’, but I don’t have any other low-thyroid symptoms, in particular no sign of plantar fasciitis, which is usually one of the first symptoms of ‘too low’, so I think the feeling awful must have some other cause. I’m going to leave it where it is for a bit but I expect to be back soon to feeling fine except for being too hot, at which point I’ll start to reduce it again.

My near-total lack of appetite carried on for a week, during which I mainly ate bits of toast and butter. Despite what must have been a terrifying calorie deficit I didn’t seem to lose much more weight. I was sometimes lethargic and sometimes too hot.

And then suddenly on the 24th my appetite came back all of a sudden, like someone turning on a light, and I bought a big bag of potatoes and baked the lot and started eating them ravenously. And then carried on doing the same thing for days. They were just delicious. I still wasn’t eating very much in terms of calories I think, although I wasn’t counting, but potatoes aren’t very energy dense and probably most of the energy was from the vast quantities of butter I was putting on them. I also made a new batch of beef and vegetable stew just in case I was missing out on protein or vitamins, but I didn’t actually eat much of it, it was more of a sauce for the potatoes, and I never put any more beef in it so it just got thinner and thinner as I added vegetables and tomato passata.

And my weight started to rise, and continued to rise for a week. I was writing a post in my head where I announced that my confident predictions had failed so catastrophically that I was abandoning all my beliefs and deciding that I just knew nothing, and that people really were just a big bag of calories, equilibria didn’t exist and appetite was totally mysterious and must be controlled by the whims of the gods.

But after about five days of this, the trend reversed and my weight started to fall again. This morning I was 95.2kg and if you ignore that and only look at the seven-day average I’ve lost a bit less than 3kg in the three weeks since I came home.

In hindsight I think a week of not eating hardly at all had emptied my guts and my glycogen reserves and as soon as I started eating potatoes in vast numbers all that just filled up again and caused a ‘dead-cat bounce’ to appear over what’s actually been three weeks of losing fat at about the fastest rate I’d be happy doing so. There doesn’t seem much point in trying any sort of intervention until that rate of descent has slowed, so I’m just going to carry on eating ad-lib.

In total I’m going to take that as a confirmation of my prediction. I was pretty confident of that, and very surprised when it seemed to not be happening. The interesting question now is where it will stop.

The only fly in my ointment is that I’ve been feeling absolutely awful. I’ve had a couple of mild sniffles in the last couple of weeks, and maybe they were something to do with it. I can’t believe that a couple of weeks ago I wrote ‘the near-complete remission of my chronic fatigue syndrome’. It’s totally back now.

It’s not nearly as bad as it was before I started taking thyroid, and I’ve got none of the many other symptoms apart from the tiredness, but most days for the last couple of weeks I’ve been waking up feeling a bit sluggish, and then by five o’clock I’m so tired I go to bed for a couple of hours, and usually wake up fine and end up going to bed late and the cycle repeats. I feel more tired than I have done for years, and I’m ignoring all sorts of things that need doing.

A couple of days ago I noticed that I hadn’t eaten anything but plants and butter for weeks and I wondered if I’d somehow managed to give myself a vitamin B12 deficiency. So I went and bought some more beef and some cheese, and ate a load of ancient methylcobalamin pills which I had lying around because they used to really help. And that does actually seem to have helped. The last couple of days I’ve been almost back to normal. It doesn’t really fly as an explanation though, since B12 deficiency should come on very slowly, and I should be craving foods that contain it.

I am feeling a bit hot during the day, but that’s not showing up in morning temperature readings which have been curiously low.

Predictions

Last time I came back from Mum’s I was around 96kg and my weight fell to 94.75kg under its own power before I started messing. Now I look at it there was even a little dead-cat bounce back then, although less noticeable. That was last September and the situation should have improved since then, especially since there’s been a massive weight yo-yo since then.

So I expect that to happen again at least, and if there’s anything to the yo-yo theory it should go a bit lower than that this time. The rate of weight loss should drop a bit as I approach a new lower equilibrium, at which point I’ll probably switch over to ex150ish or some variant and see how low I can get.

Fatigue-wise I guess I expect that this is some sort of transient effect of God-knows-what and I’ll recover and feel well again soon, but since I have no idea what’s causing it I’ve got no idea whether that’s true or how fast it will happen. If it doesn’t get better on its own I might start doing the full keto ex150ish just to see if that helps, because I usually feel great in ketosis.

Wish me luck. I know most people who read this substack are interested mainly in the weight loss part, but for me the metabolic effects of giving up PUFA are most of the benefit. The weight is cosmetic. I want my energy back. I want my mind back. The very fact that I’ve finally got round to writing this post is a hopeful sign I guess.

19/01/26 96.4 36.75 0.018 0.018 138/79/51

18/01/26 98 36.8 0.01 0.01 135/81/48

17/01/26 98.2 36.6 0 0

16/01/26 99.1 36.7 0.01 0.01

15/01/26 100.5 36.8 0 0

14/01/26 99.8 0.01 0.01

13/01/26 98.7 36.7 0.01 0.01

12/01/26 98.7 37 0.008 0.008

11/01/26 98.6 36.5 0.01 0.01

10/01/26 98.9 36.65 0.01 0.01

09/01/26 98.2 36.7 0.01 0.01

08/01/26 98.6 36.5 0.01 0.01

07/01/26 98.5 36.6 0.01 0.01

06/01/26 99.4 36.7 0.01 0.01

05/01/26 98.9 36.9 0.008 0.008

04/01/26 36.5 0.01 0.01

03/01/26 97.6 36.7 0.01 0.01

02/01/26 97.4 36.6 0.01 0.01

01/01/26 96.6 36.85 0.01 0.01

31/12/25 97.8 36.7 0.01 0.01

30/12/25 96 36.9 0.01 0.01

29/12/25 97.8 36.6 0.01 0.01

28/12/25 98.1 36.5 0.01 0.01

Predictions From The Last Post

I’ll be here another couple of weeks yet, and I’m expecting to gain even more weight. I’d expect it to start to slow down soon and I’d expect to stabilise somewhere below my all-time record of 99kg, but there’s no sign of that yet. If my seven-day average goes above 99kg and stays there for any significant length of time that probably means I’m wrong about a lot of things, in particular the idea that giving up PUFAs should eventually fix obesity. And I’m almost there! Current seven-day average is 97.4kg.

I’m still expecting my thyroid dose to come down at some point.

Once I’m back in Cambridge and in control of my own food, I’d expect to start losing weight quite rapidly, down to something like 95kg at least whilst still eating ad-lib, and I’ll be quite surprised if that doesn’t happen.

Over the Christmas period, I continued my policy of accepting everything Mum offered as long as I could bear the thought of eating, and to my amazement my hunger levelled off and I actually lost weight slightly over Christmas and New Year, in spite of consuming more than half of a huge (8kg) turkey in various forms.

In spite of that turkey being the most heritage-breed tasty organic animal-ethics turkey that money can buy, that was probably the most PUFA I’ve eaten this year. Although ChatGPT tells me that there isn’t actually a great deal of PUFA in turkey and it was probably about 50g of PUFA in total over about ten days.

Come the New Year we finally ran out of turkey curry and it was back to the more usual roast beef and steaks and cheese and crumbles and ice-cream (the chips made with beef dripping continued in huge quantities throughout), and my weight started to rocket up again.

I felt really well throughout, no traces of tiredness or headaches at any point once the earlier sulphite poisoning had cleared. Went for a walk every day, felt comfortably warm all the time but not obviously overheated (it was cold up in the Pennines, close to zero most days, but I wasn’t feeling too hot at home either, and our house is well heated).

On the last day I was home my weight was 100.5kg and my seven-day average was 99.2kg, both record highs, and I did finally feel too hot, so I dropped a dose of thyroid.

In terms of seven-day averages over the whole period, that’s a gain of around 6.5kg in my four weeks away. A titanic amount, and more than I was expecting even given that I wanted to put on as much weight as possible for yo-yo purposes.

If my weight had stayed there, slightly higher than it was at its worst point two and a half years ago, I would have been really very surprised.

Because lots of good things have happened over the last two and a half years. The almost complete remission of my once-crippling chronic fatigue is the best of them, but before that my weight was rising steadily at 4kg/year, and that stopped dead the minute I finally stopped eating peanut butter and thus actually gave up PUFAs.

So I’d have been in the position where stopping eating PUFAs stopped the uncontrollable weight gain, but two and a half years of pretty much zero PUFA had done nothing at all to fix the problem I already had.

The previous highs were also just after visiting Mum, so it would imply that my ‘equilibrium under maternal conditions’ had gone slightly higher that it had been two-and-a-half years ago.

And even that’s quite odd, because I’ve gone home for a month many times over the last couple of years, and although it’s always produced massive weight gain, I’ve never gone over 97kg before.

Which would all be quite weird in itself.

But it would also refute almost all the hypotheses about the cause of obesity being to do with modern food. Because my PUFA-free and sulphite-free diet is also by necessity a diet very very low in processed food of any kind. The only things I regularly eat that might count as processed food are dairy products (but only the sort where the only ingredient is milk), and bread (of the sort where the only ingredients are wheat, yeast, and salt).

The only modern food-related things left would be contamination from plastic packaging, or the fact that modern flour is different to ancient flour.1

And even they don’t fly, because almost everything comes in plastic packaging, and that’s just as true now as it ever was, and I’ve carried on eating modern flour as much or more than I ever used to do, so why would my weight have stopped rising at all?

Luckily for my sanity, the minute I got back to Cambridge my appetite fell off a cliff. On the way from the station to the boat I bought a packet of wholegrain rye bread ( https://www.waitrose.com/ecom/products/schneider-brot-german-vollkornbrot-bread-10-slices/055009-27625-27626 ), some milk and some butter to make toast before I went to bed.

And that’s about all I’ve eaten for the last three days. I did have a steak ciabatta in the Fort St George with friends on Saturday, but it wasn’t very big. Last night I bought another packet of rye bread and a pot of ice-cream, but I’ve only had the ice-cream and a couple of slices of toast since then. I’ve only eaten about half the butter.

And not entirely unpredictably, my weight has started to fall off a cliff.

This morning I was 96.4kg and the most recent seven-day average was 98kg.

So provisionally I think my anti-PUFA (or at least something in modern food) beliefs have just survived, with the extra wrinkle that this time I was actively trying to gain weight, and so not refusing food just because I wasn’t hungry (there is always room for ice-cream, it seems...).

And so I think I’ve managed to push myself over my previous record by accidentally willpowering myself to eat even more than I usually would at home, and now I’m suffering some sort of mad rebound where my body has suddenly noticed that I’m very overweight and switched off my appetite almost entirely.

The only surprise is that I felt fine on Saturday the day after I got back, and spent a lovely day talking to people and bouncing around energetically, but on Sunday I felt absolutely awful, sluggish, lethargic, too hot, depressed, listless and headachy. I dropped another dose of thyroid because I was feeling too hot, but then decided that was a bad idea and took double this morning to make up. Today I feel better than yesterday but still pretty ropey.

I wonder if despite the fact that most of what I’ve eaten has been rye bread toast with butter, I’ve actually eaten so little that I’m going into ketosis and have got “keto flu”. Or it may be a virus, I do have a slight sore throat.

Christ knows. Anyway let’s see what happens next. I’ll take an electrolyte pill just in case.

I’m not going to do anything deliberate for a while, just eat what I want when I want (no-PUFA, no sulphites). I want to see what happens if I take my hands off the controls.

Predictions

I expect my lack of appetite to continue, I’m massively visibly overweight and my body appears to have suddenly noticed this. Weight should continue to fall, at least until I get back to my previous free-living equilibrium which seemed to be lower than 95kg. I’ll be really surprised if that doesn’t happen.

I expect to need to reduce my thyroid dose. At the moment I’m torn between ‘I’m too hot’ and ‘I feel really tired’, but I don’t have any other low-thyroid symptoms, in particular no sign of plantar fasciitis, which is usually one of the first symptoms of ‘too low’, so I think the feeling awful must have some other cause. I’m going to leave it where it is for a bit but I expect to be back soon to feeling fine except for being too hot, at which point I’ll start to reduce it again.

Current Beliefs

I continue to believe in CICO, it’s a law of physics and if I’m certain of anything in this world it’s that classical physics applies almost perfectly to questions of nutrition, but I also think it’s useless as an explanation of the modern epidemic of obesity or as a method of losing or gaining significant weight.

I continue to believe that my weight is under homeostatic control, and that one of the main things that my appetite is for is to control the amount of body fat that I carry. I’d be amazed if that wasn’t true.

I continue to believe that PUFAs (or something else in modern food) were the cause of my metabolic curse, and that no-PUFAs has pretty much fixed it over the last two-and-a-half years. I’m pretty sure of this.

I continue to believe that PUFAs (or something else in modern food) are the cause of obesity. Eating lots of PUFAs raises2 the set point that your appetite is aiming for, but since they’re stored in your body fat in large amounts renouncing them only fixes the problem very slowly. Again I’d be quite surprised if this wasn’t true.

I continue to believe that something about what you eat (very possibly the protein content) can also change that set point. This seems very strange, and shouldn’t be true, indeed doesn’t seem to have been true historically, so I think there must be some interaction between e.g. protein and PUFAs. I’ve seen this apparently happen so many times that I’d be quite surprised if that wasn’t true.

I am puzzled by the fact that my metabolic curse appeared long before I started to have any sort of obesity problem, and yet has been almost fixed while I still have a weight problem. If they have a common cause, that is very strange. This is my main reason to suspect that my whole framework is wrong somehow.

In short, my experiences over the last month or so have shaken my faith but haven’t been enough to destroy it. I’m still convinced that the same things are true, indeed I can’t think of any other explanations that hold water, but I’m less confident than I was.

28/12/25 98.1 36.5 0.01 0.01

27/12/25 98 36.9 0.01 0.01

26/12/25 97 36.75 0.01 0.01

25/12/25 97 36.8 0.01 0.01

24/12/25 97.8 36.5 0.01 0.01

23/12/25 97 36.85 0.006 0.006

22/12/25 97.1 36.6 0.01 0.01

21/12/25 96.9 36.7 0.008 0.008

20/12/25 96 36.7 0.008 0.008

19/12/25 96.7 36.7 0.008 0.008

18/12/25 96 36.8 0.006 0.006

17/12/25 96.1 36.9 0.01 0.01

16/12/25 0.01 0.01

15/12/25 93.6 36.64 0.01 0.01 135/80/51

14/12/25 93.2 36.47 0.01 0.01 132/77/45

13/12/25 93.4 36.69 0.01 0.01 138/86/47

12/12/25 93 36.83 0.008 0.008 138/78/62

11/12/25 94.1 36.48 0.01 0.01 140/83/50

10/12/25 93.1 36.81 0.008 0.008 147/90/54

09/12/25 92.8 36.89 0.007 0.007 137/81/56

08/12/25 92.2 36.9 0.01 0.01 143/79/54

07/12/25 92 37.13 0.01 0.01 141/85/50

06/12/25 92.7 36.89 0.01 0.01 130/73/47

05/12/25 93.1 36.57 0.01 0.01 134/84/47

04/12/25 91.6 36.98 0.012 0.012 136/79/49

03/12/25 92.7 36.64 0.01 0.01 133/77/48

So I went home for Christmas without writing down my predictions in advance, which is very bad, but I’ve tried to reconstruct my state of mind from three weeks ago and I think this is what they would have been:

The Sorts of Predictions I Would Probably Have Made

I’ll go home and quite quickly become hungry and start eating more than is usual. I’d expect to feel hot and have to reduce my thyroid dose.

My weight will rise quickly at first, then slowly, until it hits a new equilibrium, but I don’t know where that will be. My best guess at an equilibrium weight when eating ad-lib and in control of my own food supply is definitely below 97kg and probably somewhere below 95kg but I suspect that there’s something about going home which shifts that set point higher. I’d actually hope (since my plan here is to gain as much weight as possible over Christmas) that I’d be able to get back up to 97kg and possibly even higher. I’m going to keep a food diary at least at first to see if I can work out what causes this weight gain effect.

Eating ad-lib before going home my weight had been rising fairly quickly and before I left Cambridge my last measurement was 93.6kg. I didn’t eat much that day until I got to Mum’s, and when I arrived I was instantly presented with an enormous piece of roast beef, easily a kilo, and some chips (steak fries) and a pot of home-made piccalilli. They were all delicious.

I ate about half the beef and all the chips, felt full1, then sat around for a few hours and went to bed.

The next day I didn’t weigh myself for some reason but I reckon I probably weighed about the same that morning. But I was really hungry.

My first act was to raid the fridge and eat a load of cheese, then Mum produced fruit and yoghurt and coffee for breakfast. I went for a walk and came back starving, ate some more of the beef and half of a delicious home-made apple crumble with Greek yoghurt, then felt tired and tried an afternoon nap but couldn’t sleep. I got up and ate more crumble and more yoghurt, then for dinner I had most of the rest of the beef, lots of chips, some runner beans, and even more yoghurt. Despite having eaten about twice as much as usual, to my amazement I got up in the middle of the night feeling really hungry and polished off the rest of the crumble and some more Greek yoghurt2.

The next day I was 96kg bang. Two and a half kilos heavier in a day. I felt slightly too hot and I was still really hungry, breakfast was fruit and yoghurt, second breakfast was oatcakes with cheese3, after which I felt sleepy but again couldn’t sleep. I went for another walk and came back ravenous to a dinner of the rest of the beef, and quite a lot of jacket potatoes and grated cheese. And once again I woke up in the middle of the night feeling really hungry and raided the fridge and ate half a litre of ice-cream at about three in the morning. 96.7kg.

This state of being really hungry all the time carried on for a few more days, but slightly to my surprise my weight stopped rising and hovered between 96 and 97kg before eventually starting to rise again.

I felt absolutely awful for a lot of this period, shatteringly tired and with nasty headaches that needed to be suppressed with frequent painkillers. In retrospect that was because Mum had cooked a curry using pre-chopped garlic4 that had sulphites in it, but it took a while to realise that, and I’d been poisoning myself for several days running. After I’d eaten the last of the curry the headaches took a couple of days to stop but have now gone.

My hunger seemed to normalize over this period, possibly because I felt so ill, and the weight gain stopped.

Now it’s actual Christmas and there are huge amounts of delicious things everywhere (turkey and chips is probably my favourite of all meals. Mum is really really good at roasting turkeys.) I’m eating more than I usually would, but it feels more reasonable, I’m not starving hungry all the time, I’m not raiding the fridge, and I’m not waking up hungry in the middle of the night.

I’m back to feeling well most of the time, plenty of energy and no afternoon naps, and my weight is currently 98kg and apparently still rising fairly rapidly.

I might be slightly too hot, but it’s pretty cold here and I’m not feeling that it’s necessary to reduce my thyroid dose to reduce overheating, in fact I’m currently sitting in a warm room wearing a jersey.

I’ve stopped keeping a record of what I’m eating, it seems pretty clear that one meal where I ate half a kilo of roast beef was enough to set off extreme hunger. I wouldn’t quite call it hyperphagia, I wasn’t eating beyond what was comfortable or trying to cram food into a bursting stomach, it was more like I got normal satiety but it didn’t last more than a couple of hours before I was hungry again.

If I had to guess, something about that huge piece of beef, probably the protein content, caused my body to decide the following day that I was really quite short of fat reserves, and so I’ve been eating at every opportunity to get them back to what it thinks is a reasonable level. Since most of the available food is protein heavy and I’ve just been eating vast quantities of whatever looked best, that seems to have set off a self-reinforcing cycle.

I’m currently heavier than I’ve been for something like two-and-a-half years and my weight is still rising. Played for and got I guess!

I’m not surprised by the effect, but I am surprised by how fast it happened and how high it’s gone.

I am also surprised that I am still taking the same amount of thyroid as I was. Previous visits home have usually involved overheating and dramatic reductions in thyroid dose, although not invariably.

Predictions

I’ll be here another couple of weeks yet, and I’m expecting to gain even more weight. I’d expect it to start to slow down soon and I’d expect to stabilise somewhere below my all-time record of 99kg, but there’s no sign of that yet. If my seven-day average goes above 99kg5 and stays there for any significant length of time that probably means I’m wrong about a lot of things, in particular the idea that giving up PUFAs should eventually fix obesity6. And I’m almost there! Current seven-day average is 97.4kg.

I’m still expecting my thyroid dose to come down at some point.

Once I’m back in Cambridge and in control of my own food, I’d expect to start losing weight quite rapidly, down to something like 95kg at least whilst still eating ad-lib, and I’ll be quite surprised if that doesn’t happen.

There is a video with this title, my sources inform me:

I haven’t watched it. Perhaps someone with more patience for watching videos could let me know if the guy says anything interesting in it. It doesn’t look promising.

But I do feel the need to reply.

Yes we know.

To a first approximation, my weight never changed a bit between getting to my full growth and getting old, and I always ate exactly what I liked in whatever quantity I liked. And sometimes I did nothing because I am really lazy, and sometimes I was fanatically sporty, because sports are fun and I am very competitive.

And in fact, that’s how animals have to work. An animal that reacted to plentiful food by becoming grossly overweight would just make itself slow, valuable prey, and that’s not the way to have lots of living descendants.

An animal that let its fat reserves dwindle because it had been using more energy than usual even though food was available would leave itself vulnerable to food shortages.

There are trade-offs in how much fat to carry. Animals that stray too far from the optimal choice don’t leave as many descendants as animals that stick closely to the right value.

We are animals. African animals, to a first approximation.

Calories are causal in obesity. Calories are not the cause of obesity.

CICO is true, it is a law of physics. CICO is not the answer. Any more than ‘gravity’ is why your plane crashed.

Some objections were raised to my reply:

If calories caused obesity, then eating saw dust would make us fat.

Yes indeed! Why stop at sawdust? There are 21 trillion kilocalories in a kilogram of anything. If we could extract that energy, then eating or breathing in, say, 1 kg of hydrogen cyanide would be enough to put on roughly 3 million tons of fat.

CICO is not a law of physics. Stop giving the evil people ground to stand on they don’t deserve.

No-one in this debate is evil. There is considerable confusion. Some people are wrong. Those people may well be us.

I’ve never seen anything that makes me doubt even the nutritionists’ version to within the 10% or so that the food labels are supposed to be accurate to. Calories out is hard to measure, everybody knows that, and without knowing calories out CICO can’t tell us much.

We do ourselves absolutely no favours claiming that our ideas only work if physics, or indeed basic chemistry, isn’t true.

If you really think CICO isn’t true to the point where you might notice it in a nutrition experiment, go do the actual experiment that proves it. It wouldn’t even be that expensive or difficult.

I promise you that physics and chemistry will both be very very interested! Even the nutritionists might notice, once the current generation are all dead. And you will be the man who disproved the ancient superstition of the conservation of energy. And you will be able to heat or even better cool things without using any fuel. Which would be really neat.

Laws of physics are closed-loop systems.

Drivel

There was also this comment:

This guy is probably a huge genetic outlier when it comes to resisting fat gain . The vast majority of people gain fat in a surplus no matter how they change the macros. Obese people or formerly obese gain weight effortlessly it seems.

I would imagine that almost everyone gains fat in a surplus. There aren’t many other places for the excess energy to go. The interesting question is why a lot of people, particularly modern people in the modern world, eating modern food, seem to eat more than they need.

The answer, of course, is because they’re hungry.

And then we have a real question. Why are people who have ample fat reserves, more than they were designed to carry, hungry?

Something is broken in the mechanism that controls appetite. Some aspect of modernity has broken a mechanism that worked perfectly well for billions of years.

The interesting question is “What?”

ChatGPT has written me a program based on my post Yo-Yo Theory. https://theheartattackdiet.substack.com/p/yo-yo-theory

Not wanting to count every little up-and-down in my weight record as gain or loss of fat (It’s mostly measurement noise), I’ve selected certain significant turning points from my weight records, where the seven-day average hit maxima or minima as I went from long periods of weight loss to weight gain for various reasons.

Here are the selected readings, the ones where I was in ketosis have been adjusted upwards by 1.5kg to account for the irrelevant changes in stored glycogen (water-weight)

keto_water_weight=1.5

readings = [

(”2023-05-22”, 99),

(”2023-09-14”, 92+keto_water_weight),

(”2023-10-13”, 95.46),

(”2023-11-11”, 91.6+keto_water_weight),

(”2024-04-05”, 97.44),

(”2024-05-05”, 95.50),

(”2024-08-28”, 97.16),

(”2024-09-22”, 94.88+keto_water_weight),

(”2024-10-06”, 96.6),

(”2024-11-03”, 93.4+keto_water_weight),

(”2024-12-29”, 96.6),

(”2025-01-14”, 94.07),

(”2025-03-28”, 96.94),

(”2025-07-01”, 92.37),

(”2025-09-15”, 96.2),

(”2025-11-23”, 91.2+keto_water_weight),

]

I decided that since I’ve never allowed myself to be hungry at any point, my lean mass should have stayed constant throughout. There’s been no reason to lose or gain anything except fat, so I’m assuming that I didn’t.

And I’m also assuming that the tiny amount of LA that’s unavoidable when eating food, however strict you are, is just going to balance the actual physiological need for LA. That makes the calculation simpler without, I think, affecting the result much.

ChatGPT also pointed out that when you lose weight you don’t actually burn linoleic acid in proportion to the amount in your fat. There’ve apparently been a number of experiments on this, and a number of estimates of the ‘mobilization factor’, but everyone agrees that you preferentially burn the SFA and MUFA in fat. So we agreed on a mobilization factor of 85% as being a realistic but somewhat pessimistic estimate.

That is to say, if you’ve got 200kg of fat of which 100kg PUFA and 100kg ‘real fat’, you’ve effectively got 100kg of real fat and 85kg of LA available.

So if you then lose 185kg, you’d have 0 real fat and 15kg of LA left.

Losing weight actually increases the percentage of LA in your body fat while decreasing the total amount.

Anyway on that basis we produced the graph above, and I’ve added a few lines representing LA percentages in historical populations where we’re reasonably confident what was going on.

I was surprised to learn that my own Victorian ancestors probably had the lowest percentage of LA in their fat of any human population. In hindsight this is fairly obvious. They were eating a lot of bread, and doing very little hunting or gathering, so before seed oilz were either in their diet or in the diet of the animals they ate, they had unnaturally low levels of polyunsaturated fats. In fact given that the natural state of man seems to be around 3-4%, they might even have been flirting with LA deficiencies. Luckily for them they were likely eating wholemeal bread.

At any rate I hope the graph makes my yo-yo idea more obvious. The actual numbers don’t matter so much as the idea.

The big green area is my lean mass, hopefully staying constant throughout. The red area is my natural SFA and MUFA body fat. And the yellow area is the golden glow of polyunsaturated doom.

Whenever my weight goes down, red and yellow areas shrink together, although the red shrinks more than the yellow.

Whenever my weight goes up, the red area gets larger, but the yellow area stays the same.

The proportion of yellow LA to total fat therefore goes up slightly during weight loss, and comes down quite a lot during weight gain, and that’s the black line.

I’m assuming I started at something horrific like 25% LA, high even by modern standards, since I was after all rather unwell on my diet of lots and lots of chips1 fried in varnish, and starting to become catastrophically obese.

And given all the above unjustified assumptions and made-up numbers, I calculate that I should now be down to 15%, which is about average for modern Americans, and still quite high by the standards of my own people.

I am no longer obese, and although I’m still taking a tiny amount of thyroid to keep myself going, I feel that I am close to beating my ‘chronic fatigue syndrome’. I think that even without the thyroid, I’d no longer be able to get any of the ‘dustbin diagnoses’ where they put people with hypothyroid symptoms but no actual thyroid problem, whereas for most of the last ten years if I’d stopped taking the thyroid I’d have been able to get diagnosed with any of them.

My project now is to accelerate this process.

03/12/25 92.7 36.64 0.01 0.01 133/77/48

02/12/25 92.6 36.65 0.01 0.01 135/81/49

01/12/25 92.9 36.51 0.01 0.01 144/92/52

30/11/25 92.8 36.77 0.01 0.01 145/81/48

29/11/25 91.9 36.94 0.01 0.01 149/88/49

28/11/25 92.9 0.01 0.01

27/11/25 91.6 36.9 0.01 0.01 136/84/61

26/11/25 90.9 36.68 0.01 0.01 122/84/61

25/11/25 90.2 36.98 0.01 0.01 133/76/55

24/11/25 91.3 36.83 0.012 0.012 142/89/55

23/11/25 91.4 36.77 0.01 0.01 126/78/58

22/11/25 90.8 36.74 0.01 0.01 131/76/59

I don’t actually know how this went.

Every day this second week I ate either an apple or one of the tangerines that turned up in my weekly veg bag, which ChatGPT reckons aren’t any more than 10g of carbs and shouldn’t disturb ketosis much. And that didn’t seem to make any difference at all.

And on Sunday 23rd I got hungry in a pub and bought a big greasy sausage roll and ate the biscuits which came with my coffee, and also some more biscuits which came with someone else’s coffee, only she was ‘on a diet’. ChatGPT reckons that’s about 50g of carbs in one go, which it does think would be enough to knock me temporarily out of ketosis.

But that didn’t seem to make any difference, my weight was actually lower the following day and I kept my ‘keto clarity’ throughout, in fact I was noticeably energetic and lively and a bit too hot the following day.

So whatever, I sort of stuck to the plan….

My predictions from last week were:

> Possibly more ‘ghost headaches’ associated with recarbing and then decarbing, but electrolytes should deal.

Yes to both.

> Excellent mental clarity, and the “two fuels” problem associated with ketosis. If either of these things don’t happen I’ll be surprised.

Yes, I got both those things pretty clearly all week. Twice I felt my brain had run out of fuel after long nerding, headed home to sleep, found myself cycling energetically, and then found I couldn’t sleep and was fine after half an hour, which is not at all how fatigue usually works for me. Of actual fatigue there was no sign.

> I sort of rationally expect to carry on having not much of an appetite, and thus to keep losing body fat at around 1kg per week, so in seven days time I should be around 90kg.

> And I sort of intuitively expect to plateau, which should involve appetite going back to normal, which I’ll notice because that would involve eating two pots of double cream per day instead of the one I’ve been having in coffee every day this week, and in seven days time I’ll still be around 91kg.

> So I guess I’m confidently predicting something between those two outcomes, and will be surprised if anything else happens, and tbh my money is on continued weight loss, although maybe less dramatic as I approach some sort of lower equilibrium point.

Well, I didn’t have much of an appetite, and I didn’t eat much apart from my daily coffee and cream and the odd bit of stew, and things seemed to be going as usual mostly. I even hit a new low of 90.2kg on the Tuesday, a couple of days after the sausage roll and biscuits episode.

But then my weight rose two days in succession, and I ended the week at 91.6kg, at which point I had social reasons to say bollocks to it, so I did.

After a few days of recarbing on various pizzas and bits of toast and pasta and ice cream, my weight seems to be hovering around 92.5kg (I assume fully recarbed). Maybe rising and maybe plateaued, can’t tell. I’m back to eating a more usual amount, but I’m not ravenous.

Looking at the graph, I can’t get a sense through the noise of whether I just carried on losing weight at the usual rate or whether it stopped or slowed down or reversed towards the end.

But it looks like over two weeks of ex150ish+tiny bits of carb I lost 1.5kg of fat in total. So I declare ex150ish-11 as a whole another success.

But I’m not sure whether ex150ish was just working as usual at 90kg, and would have carried on working, or whether I am near a limit below which it can’t take me.

No matter. I’ll probably find out sooner or later.

Energy-wise, as soon as I started eating all those pizzas my fatigue problems came back, and I went back to feeling shattered around 1700 and going to sleep for a couple of hours. So the last few days I’ve tried avoiding carbs in the morning and saving them until the evening meal.

This seems to have produced the ‘keto clarity’ effect without me actually needing to be on a keto diet. Presumably I’m getting tired while I’m asleep? That may or may not be a good thing, but it’s nice to be bouncy all day without having to do a low-carb diet.

That concludes the down phase of this current yo-yo, I am going home for Christmas soon.

The last time I was clearly in equilibrium was last April, when I was about 97kg eating totally ad lib (no PUFAs, no sulphites), and had pretty clearly exponentially decayed back up to that point and then stopped there, just sort of wobbling around within 0.5kg of that value.

More recently I came back from a visit home at 96.3kg and then immediately started losing weight for no reason, so I suspect my equilibrium point was probably more like 95kg in October.

I’ve no idea where it might be now, hopefully a bit lower.

I imagine it’s just as hard to force-feed yourself above equilibrium as it is to starve yourself thin. Your brain just shouldn’t be designed to allow you to do either, any more than you can will yourself to stop breathing or drinking water.

But Mum is highly skilled at getting me to eat more than I actually want, and I actually want to put on as much weight as possible this time.

So I know that if I just believe in myself and try hard, I’ll be able to get back up to 97kg. Maybe even higher! I’m taking my very largest trousers.

The days continue to shorten/lengthen, but soon the Sun will be reborn!/begin to fail! And the days will lengthen or shorten once again1, and the temperature will start to go back to something more reasonable.

Whatever your hemisphere, the blessings of Advent upon you all.

22/11/25 90.8 36.74 0.01 0.01 131/76/59

21/11/25 92.8 36.86 0.01 0.01 139/81/56

20/11/25 91.1 36.67 0.01 0.01 148/90/51

19/11/25 91.6 36.97 0.01 0.01 132/84/49

18/11/25 92 36.68 0.01 0.01 142/89/48

17/11/25 91.8 36.74 0.008 0.008 137/83/53

16/11/25 92.7 36.75 0.008 0.008 135/80/44

15/11/25 93.9 36.83 0.008 0.008 130/90/48

14/11/25 94.3 36.71 0.008 0.008 134/83/56

I’ve put my thyroid dose up a very tiny bit, to 5/500ths of the original dose, because the weather’s suddenly turned freezing, and one man’s overheating is another man’s cozy internal central heating. That’s made me feel a bit warmer, but it hasn’t started producing random fits of sweating so I think I’ll keep it there.

Last week I predicted:

Headaches on ketosis entry. The last time I tried two ex150ish bouts back to back the headaches were terrible, but I hadn’t discovered that I need to take electrolytes while losing the water weight, so I’m not sure what will happen this time. I suspect I’ll be fine and enter ketosis smoothly with maybe a slight ‘ghost of a headache’.

I got a ghost of a headache on the first day, took keto electrolytes and it went away quickly. I’ve got a vague memory that a couple of times last week I got a feeling like I was about to get a ghost headache, and took more electrolytes, but it isn’t in my notes so I must have forgotten about it before I wrote it down.

Non-existent appetite, rapid weight loss, excellent mental clarity, the “two fuels” problem where I can get my mind tired while still having plenty of physical energy. If any of these things don’t happen I’ll be surprised.

All of those things happened. At one point I’d been nerding for hours and suddenly my brain switched off and I felt tired. Then cycling home I found myself pedalling hard and going dangerously fast for no reason, which is classic ‘brain not working, body fine’.

I expect to lose 1.5 kg of water-weight immediately as I shed my glycogen reserves, then to lose body fat at around 1kg per week.

Current average is 93.6 kg, so in one week’s time I expect to be 91.1 kg, and then to bounce back up by 1.5kg over two or three days whenever I add significant carbs back in.

Bang on. I was 91.1kg on Thursday morning. That evening I went to choir, completely forgot I was supposed to be keeping keto and troughed a load of shortbread biscuits with my tea, felt all woozy and thought oops. Then I had six whiskies and on the way home I went past a kebab shop about midnight and thought “Wow I could really use a kebab”. Which is a sign of protein cravings and is not to be resisted. Mostly kebabs are lamb and salad (and some dodgy sauces which have probably got oilz-of-evil in them but not much), but they also come in a pitta bread, which is even more carbs.

Anyway that’s got to count as a “cheat day”, and it produced an adorable little weight spike the following morning, but no disturbance to my ‘keto clarity’, which I am really enjoying.

And this morning I am back down to 90.8kg, so that appears to have been completely transient and not made any difference.

90.8kg is an all-time low for me, since I started measuring these things, and it’s also the exact lowest weight I had two years ago, when I suddenly dropped 8kg with very little effort and figured both ‘problem solved’ and ‘that was too easy’.

So at this point I’m in unexplored territory, and I’m kind of feeling that the ex150 effect has stalled out for me now, even though I lost almost exactly the predicted kilogram last week. I can’t explain it, it just feels like that’s it.

On the other hand, even if 90.8kg was some sort of ‘lowest equilibrium point’ for me last year, my ‘higher set point’ has come down quite a bit since then, from a mighty 99kg at the start of all this to probably about 95kg, looking at the spontaneous weight loss I experienced last time I came back from the North.

And so I’d expect that lower point to have fallen too, so ex150ish should carry on working for a bit.

Which means I’m in the weird state where I expect to be surprised in a predictable way, which isn’t supposed to be the sort of thing a coherent mind can believe.

Still, all I’ve got to work with here is some crappy human brain, so I’m not going to pretend not to believe this weird incoherent thing. That would be even more insane.

Only one way to find out. I can handle another week of this. I’m not craving carbs at the moment, presumably my little recarb on Thursday night has something to do with this.

There are three delicious looking apples in this week’s veg bag, so they’ll get eaten at some point, which I don’t expect to make much difference apart from maybe they’ll keep the carb cravings down, but apart from that ex150ish-11 continues, at least until it starts to feel uncomfortable....

Predictions

Possibly more ‘ghost headaches’ associated with recarbing and then decarbing, but electrolytes should deal.

Excellent mental clarity, and the “two fuels” problem associated with ketosis. If either of these things don’t happen I’ll be surprised.

I sort of rationally expect to carry on having not much of an appetite, and thus to keep losing body fat at around 1kg per week, so in seven days time I should be around 90kg.

And I sort of intuitively expect to plateau, which should involve appetite going back to normal, which I’ll notice because that would involve eating two pots of double cream per day instead of the one I’ve been having in coffee every day this week, and in seven days time I’ll still be around 91kg.

So I guess I’m confidently predicting something between those two outcomes, and will be surprised if anything else happens, and tbh my money is on continued weight loss, although maybe less dramatic as I approach some sort of lower equilibrium point.