Thursday, June 20, 2013

Protein, the Thyroid Gland, Metabolism, and Conceptions About Weight Loss Diets

I apologize for the long break but I hope to be back for a while.  I’ve been getting many emails and messages since my hiatus, and, I promise, I will try my best to get to all of them.  I really appreciate the kind words I’ve been receiving, and, if I may say so without presumption, see it as a good augury of success that I’m providing decent content.  Okay, onward. 

Regarding some of these messages, a theme all too familiar is gaining weight on restrictive diets, or not being able to eat “anything” without getting fatter.  I’m working on a guest post for Matt Stone’s site about this topic, and ways in which to overcome it, especially those who have been lifelong dieters or under-eaters.  One person emailed me recently saying that she could not eat more than about 700 calories per day without gaining weight.  This has been a matter of absorbing interest of mine of late, and I have some ideas I wish to delve into, but herein, I will briefly discuss the one macronutrient that, I think, almost everyone agrees is the least fattening of all the macronutrients: protein.

The person who I think made the soundest points and most compelling argument for getting adequate amounts of high quality protein was the nutritionist, Adelle Davis.  According to Davis, low protein intakes were a major cause of fatigue, bad posture, thinning hair, brittle nails, water retention and swelling, low resistance to infections, weak digestion, and poor circulation.  In a word, inadequate protein intake accelerated aging. (For what it is worth, I've found that eating about 15 to 20 grams of protein at each meal also elevates my mood for hours afterwards.)

The thyroid researcher and clinician, Broda Barnes, however, noted that high protein, low calorie diets, often employed to treat diabetics at the time, had an inhibitory effect on the thyroid and metabolic rate, and that he could eat about 1,000 extra calories, without gaining any weight, by eating less protein and disproportionately more (mainly animal) fat, while keeping his carbohydrate intake low.

Why a high protein intake would have an inhibitory effect on the thyroid, I'm not completely sure yet.  Most obviously, on such a diet, much energy is expended in converting protein to glucose, and, over time, the counterregulatory hormones are maintained at higher levels.  Cortisol is one such hormone that inhibits the conversion of T4 to T3.  Adrenalin, whose effect on tissues is permitted by T4, is another such hormone that inhibits insulin secretion and stimulates the hypothalamic-pituitary-adrenal axis, further reinforcing the inhibition on the conversion of T4 to T3

High protein diets without sufficient amounts of fat or carbohydrate appear to aggravate hypothyroidism, and so, long-term, are probably ineffective for weight loss, and unnecessarily restrictive.  Protein is often said to be the most satiating nutrient, but I think this is because of its effect on the thyroid and metabolism, as much as it is the fact that it is meeting the body’s need for it.  The resulting hormonal changes would also tend to favor the storage of fat in the abdominal area, further inhibiting the thyroid,1 and the resulting metabolic changes would tend to favor the elimination of thyroid hormone from the body.2

Ray Peat has taken the matter further, suggesting that it is specifically the cysteine, methionine, and tryptophan amino acid residues in proteins that are anti-thyroid and anti-metabolic, and on this basis, recommends to minimize the consumption of muscle meat in favor of gelatin, which is unusually deficient in cysteine and methionine and lacks tryptophan (and histidine) altogether. 

As to how effective gelatin is in building and maintaining bodily protein, especially when used as a major source of protein in the diet by adults, I have my doubts, but as a supplementary source of protein, it could provide the optimal balance of amino acids to support regeneration and repair without impacting the thyroid negatively. 

Small amounts of gelatin added to the diet, for instance, promotes positive nitrogen balance, by virtue of its great protein sparing ability, such that we could probably get away with eating less protein; herein lies gelatin's greatest benefit.  Gelatin also has been shown to enhance the digestion of other, less digestible proteins — most notoriously plant proteins.3

I have not experimented with large amounts of gelatin (I do make extra-firm Jell-O and eat marshmallows occasionally), and I probably will not until I see more evidence, including anecdotal evidence, for including it as a part of my regular diet.  Generally, most fruits are missing tryptophan and methionine; most vegetables are missing tryptophan; and legumes (including peanuts) are missing methionine. 

Stress, really, of any kind, when prolonged, increases our requirement for protein, as our bodies do not store protein as it does carbohydrate and fat.  Once nitrogen balance becomes negative, bodily tissues are increasingly drawn upon, and we begin to waste away and lose function.  However, animal studies have shown that very high protein intakes, about 25 percent of total calories, lead to greater body fatness than lower protein intakes, or about 5 percent of total calories — in line with the points made above.  Further, textbooks generally say that merely 35 to 45 grams of protein are needed to prevent negative nitrogen balance — provided energy requirements are met by carbohydrate (or fat).4 

It is but fair to say that context is important, and protein requirements will vary per your own circumstances; we should strive, for all intents and purposes, to thrive eating the least amount of protein, and this means keeping stress, of any kind, as low as possible.

(Consider uncontrolled diabetes, a condition in which carbohydrate becomes less available as a source of energy; tissue wasting from negative nitrogen balance follows as a result.  In this sense, carbohydrate spares protein.)

Balanced proteins, gotten from eating whole, complex animals and animal products, such as sardines, anchovies, eggs, milk products, whole chicken, shellfish, etc., I think, are the best protein sources.  You will have to fine-tune the amount, but I have found that 15 to 20 grams of protein per meal, with plenty of carbohydrate is ideal for me.  I prefer sugar to starch because too much of the latter I think eventually turns the intestines into a yeast pot. 

I have been told that people recommend to restrict both carbohydrate and fat, and to increase the intake of protein as the ideal way to lose weight. (This is actually the commercialized, perverted version of the Paleo diet.)  It is difficult to avoid saying that this represents one of the worst, and unnecessarily difficult, methods to lose weight and promote health — hormones and metabolism be damned.


1.       Muscogiuri, G. et al. High-normal tsh values in obesity: Is it insulin resistance or adipose tissue’s guilt? Obesity (Silver Spring, Md.) 21, 101–6 (2013).
2.       BregengĂ„rd, C. et al. The influence of free fatty acids on the free fraction of thyroid hormones in serum as estimated by ultrafiltration. Acta endocrinologica 116, 102–7 (1987).
3.       Gotthoffer, N. R. Gelatin in nutrition and medicine. 162 (Great Lakes Gelatin Company: 2012).
4.       Guyton, A. & Hall, J. Textbook of Medical Physiology. 1104 (Saunders: 2006).