Christmas Mom Test 2025: Initial Phase

A Glorious Success

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:

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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.

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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.

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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.

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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.

1. full as in sated, not full as in bloated

2. Greek Yoghurt is the good stuff, really thick and about 7% fat, mostly saturated. I ate about a litre of it that day, so that’s about 1000kcal just in the stuff I was using as a dressing for the huge crumble that I ate all of in one day during gaps between proper meals.

3. Two oatcakes. But they were both about the same size as a frying pan, and they were buried under a layer of molten blue cheese. We eat well, in the North.

4. Instead of using, say, the perfectly nice cloves of fresh garlic that are lying next to the perfectly good garlic press which is lying right next to the cooker.

5. Which was an apparently equilibrium weight achieved during a visit home before I finally managed to cut linoleic acid out of my diet.

6. Actually maybe not, there might be some sort of high-protein overshoot effect. But it certainly shouldn’t stay there for very long after I get back.