Theories
New PUFA/Protein Theory
= Old PUFA Theory + Epicycle
Epicycle
If you eat protein over the amount that you need for repair and maintenance and start burning the excess as fuel, that will interfere with your already rather limited ability to burn PUFAs for fuel.
In the absence of excess protein, you can probably deal quite well with some limited amount of PUFA. There are, after all, small amounts of PUFA in your natural diet, and without them you will die.
In the presence of excess protein, your ability to deal with more PUFA than usual is reduced, likely proportionately to the amount of excess protein.
Old PUFA Theory
My old theory, now refuted and renounced, was something like:
Fats need to be broken up in order to feed the Citric Acid Cycle.
Double-bonds in fats are bad.
Double bonds can be broken, but they need a different pathway.
Human fat metabolism is designed to deal with animal fat.
Animal fat is half-saturated, half unsaturated, so it will have around 34 C-C bonds to one C=C bond, a ratio of 34:1
Polyunsaturated fat mainly means linoleic acid, which will have two C=C bonds to 17 C-C bonds, a ratio of 17:2
Too much PUFA, too many double bonds, overload that pathway. The relevant pathway has some slack, but it cannot deal with working four times as hard as it was designed for.
If you eat too much PUFA, some of your fuel cannot be burned.
That leads to:
Metabolic Slowdown, because your mitochondria are clogged with fats that cannot be burned
Fat level sensing corrupted, I don't know why. But one design for a total fat sensor is going to be something like: When I'm trying to burn fat, how much energy am I getting?
And that leads to:
Hypometabolism: You'll look mildly hypothyroid, including low body temperature.
And:
Your homeostat believes your fat stores too low
Your homeostat increases your appetite to try to add energy to your stores.
And that directly leads to weight gain.
That theory, which I have never formally believed, but sort-of-believed for the last six months, and now do not believe in, makes two predictions:
Action: Eat PUFAs over a certain safe level.
Result:
Too much PUFA to burn freely.
Your metabolism is clogged and runs slow
The spare fuel either hangs around in your cells, or gets stored as polyunsaturated body fat
Appetite increases
Weight gain
Tiredness
Stored PUFA levels rise
After a while, you don't even need to eat PUFAs any more. The stored PUFAs are enough to clog your metabolism on their own. Which means that even if you stop eating PUFAs, you'll still run slow.
And that's especially true if PUFAs are preferentially released from fat cells, which they may or may not be, I have no clue.
and:
Action: Stop eating PUFAs altogether
Result:
Only stored PUFAs fed into Citric Acid Cycle
Fat burns a little more easily
Metabolism runs a little better
Fat level signal becomes slightly more accurate
Homeostat realises fat stores are actually a bit too high
Loss of appetite
Weight Loss
You have slightly more energy
And also:
Stored PUFA levels fall
Everything just gets better in general, and the longer you keep it up, the lower your PUFA stores become, and the more you go back to normal.
And that's especially true if PUFAs are preferentially released from fat cells, which they may or may not be, I have no clue.
Thyroid and Hypometabolism
There are a lot of causes of hypometabolism, which is when your metabolism just runs slow, which causes a spectacular array of symptoms as all your systems fail at the same time.
Behold the long and pathetic list:
https://stopthethyroidmadness.com/symptoms/
One of the many possible causes is a damaged thyroid gland. (Primary Hypothyroidism)
If you have that, it’s easy to detect through the TSH test. The control hormone that the brain uses to control the gland goes through the roof trying to get the gland to produce enough of the hormones that control resting metabolic rate.
If that’s the problem, then thyroid drugs are a sovereign patch. Not a cure, but they fix all the symptoms and work really well.
But there are many other possible causes. Anaemia, for instance, Starvation, Iodine Deficiency, etc, etc.
It’s possible to have hypometabolism without the cause showing up on any test known to medicine.
That tends to get written off as psychological or at least mysterious and hypochondriac:
Major Depression, Chronic Fatigue Syndrome, Fibromyalgia, Irritable Bowel Syndrome, are all names for the symptoms of hypometabolism.
It can be worth trying thyroid drugs to patch this. It worked really well for me. There’s a long line of quack doctors/unconventional heroes who claim that it works really well in most cases.
Standard medical advice is never to even try it, but I don’t know why.
One exception is for Major Depression. Psychiatrists will sometimes try thyroid when everything else has failed. It seems that it sometimes works.
The “Epidemic of Hypothyroidism”
Ancient Lunatic / Heroic Independent Minded Old-Time Endocrinologist Broda Barnes invented his own test for hypometabolism, which is to measure waking temperature as a proxy for basal metabolic rate.
He thought he saw an epidemic of hypothyroidism/low waking temperature sweeping through the population of America in the years after the second world war.
He treated it all with thyroid drugs, and reported huge success.
I think he really saw what he said he saw, but I think he was wrong about the cause.
I think there really is an epidemic of hypometabolism. I don’t know what’s causing it. I think thyroid drugs can often help.
I wonder if the root cause is polyunsaturated fats.