Protein

Protein intake is a critical nutritional variable whose optimal quantity and source are determined by metabolic rate, age, and the specific balance of amino acids consumed. Peat argued that a minimum of 100 grams of good protein daily was required for mental and physical efficiency, even for sedentary individuals, based on a military study. 3 He later suggested that for older people, an intake of 120-150 grams might be more appropriate, as the 100-gram figure represented a baseline for preventing a catabolic state. 2 Falling below this threshold triggers a systemic proteolytic state, where the body senses deficiency and breaks down the thymus gland, lymph nodes, muscles, and skin to supply essential amino acids to vital organs. 2

The amino acid composition of the protein source is more important than the absolute quantity. Peat consistently warned that the tryptophan, cysteine, and methionine found in high concentrations in muscle meats are directly antithyroid and promote stress hormones like serotonin and cortisol. 3 He noted that Broda Barnes had to double his thyroid dose when significantly increasing his meat consumption. 2 In contrast, gelatin (or collagen-rich foods like skin, tendons, and bone broth) lacks these suppressive amino acids and is rich in glycine, which antagonizes the excitatory tryptophan-serotonin-estrogen-prolactin system. 3 Peat recommended consuming 5-10 grams of gelatin alongside a serving of muscle meat to balance the amino acid profile entering the bloodstream, and suggested that a large portion of the daily 100-gram requirement could be met with gelatin. 3

The physiological context of the individual dictates the ideal protein intake. A young, growing person with a high metabolic rate requires more of the essential amino acids found in muscle meats for tissue replacement, such as making hair, skin, and gut cells. 5 However, for a hypothyroid person or someone over a certain age, an excess of muscle meat can further suppress thyroid function and promote a stress response. 3 Peat observed that food proteins stimulate insulin secretion, which can lead to a compensatory rise in cortisol to prevent hypoglycemia; this cortisol then increases circulating tryptophan and cysteine from muscle tissue, which together enhance aromatase activity. 6 Roddy and Sgourakis have discussed the idea that lowering protein, particularly from muscle meat, may be beneficial past a certain age or in a state of illness, while shifting intake toward gelatinous components and shellfish could allow for a higher total protein intake without negative effects. 8

The quality and digestibility of the protein source are paramount. Peat considered animal proteins such as milk, cheese, and eggs to be superior to plant proteins from nuts and beans, whose digestibility and amino acid balance are not equivalent. 4 He noted that a quart and a half of milk, a few eggs, and some cheese could easily meet the daily requirement. 4 The liver requires adequate dietary protein to produce albumin, a factor correlated with the protein content of growing hair root bulbs. 2 However, Peat cautioned against relying on powdered protein supplements, which lack the full spectrum of nutrients found in whole foods like fruit, eggs, and liver, and emphasized that traditional diets consuming whole animals provided a much better amino acid balance than modern diets focused on refined muscle meats. 6