Ray Peat on testosterone

January 29, 2026

The stability of testosterone and the lower adaptability in men

"The primary male hormone, testosterone, has chemical and functional properties of both estrogen and progesterone. This combined function gives men short-term stability (fewer goiters, migraines, etc.) but less adaptability in the long run (higher mortality in infancy and old age)."

Nutrition For Women

Substances that counteract estrogen in cancer therapy

"Anything that causes tissue atrophy tends to promote cancer. The important question is: What can trigger differentiation and useful function in cancer cells? There are many substances that promote differentiation and counteract the effects of estrogen, and some of these have proven useful in cancer therapy. Among the substances that counteract estrogen are dopamine and nickel, prolactin inhibitors; chalones, tissue-specific proteins that inhibit cell division (and possibly, more briefly, the peptides of memory); the aprotic solvents DMF and possibly DMSO; progesterone and testosterone; thyroxine and iodine; magnesium-ATP, the stable form of the biological energy molecule; vitamin A, a protein-sparing nutrient that promotes differentiation; and vitamin E (as well as the closely related coenzyme Q, or ubiquinone)."

Nutrition For Women

Estrogen increase due to stress and its effects on male behavior

“Stress leads to an increase in estrogen and a loss of anti-estrogens such as thyroid hormone, progesterone, and (in males) testosterone. Male apes that are bullied have reduced testosterone levels, and this effect persists long after their environment has improved. The stress of submission appears to lead to an adaptation toward passivity. Their passivity prevents further injury, but we don't know how stressful their continued submission is.”

Nutrition For Women

Metabolic inefficiency in the estrogen-dominated state compared to the oxidative state

"Energetically, the estrogen-dominated metabolic state is less efficient than the oxidative state, which is dominated by the thyroid gland and progesterone (or testosterone). The estrogen state—similar to the state of learned helplessness in rats—is parasympathetic in that many chemical equilibria have shifted away from the mobilized sympathetic or adrenergic state. For example, the estrogen state lowers blood sugar, while the mobilized state conserves glucose by oxidizing fat."

Nutrition For Women

The role of the liver in estrogen metabolism and its effects on libido

"Normally, the liver treats estrogen like a poison and removes it from the body immediately. If the liver becomes sluggish due to malnutrition or too much estrogen (or other damage), it can allow the hormone to accumulate to very high levels. Since estrogen metabolically counteracts progesterone and testosterone, I think the pill could decrease libido by counteracting these other hormones."

Nutrition For Women

Glucose and hormones to relieve schizophrenia symptoms

"Pfeiffer investigated the relationship between porphyria and certain forms of schizophrenia, but I don't think he mentioned that a good dose of glucose or an anti-estrogenic hormone like testosterone or progesterone would make the symptoms disappear."

Nutrition For Women

Progesterone therapy for male infertility and sports-related infertility

"Progesterone is the precursor (after acetate and cholesterol) for all other steroid hormones, therefore it can also be used in men. It (or its precursor pregnenolone) has been used for prostatitis, arthritis, and male infertility. Large amounts would likely suppress LH and lower testosterone synthesis, but smaller amounts (especially in older men) appear to increase sperm count and motility. In male and female athletes who become infertile, it generally seems to be the appropriate therapy, usually in combination with thyroid hormone replacement therapy."

Nutrition For Women

Stress, seasons and hormone levels in humans

"Excessive stress (by increasing estrogen and/or depleting progesterone, etc.) can trigger symptoms in someone who has never had them before. A summer in Alaska, with unusually long days, can alleviate the symptoms of a chronically affected person. Dark, cloudy winters in England or the Pacific Northwest are strong stressors and lead to lower progesterone in women and lower testosterone in men."

Nutrition For Women

Effects of stress on the thyroid gland and hormones

"Stress inhibits the thyroid gland and can lower progesterone (and/or testosterone) while increasing estrogen. Recent work by Siiteri and his group shows a hormonal involvement in various autoimmune diseases. Women are much more susceptible to these diseases than men."

Nutrition For Women

The anti-estrogenic effects of testosterone and progesterone

“Testosterone and progesterone both have a direct anti-estrogenic effect.”

Nutrition For Women

Normalization of the immune system through testosterone and progesterone

"Some of the changes associated with aging are likely related to autoimmune reactions, in which the body attacks itself; both testosterone and progesterone normalize the immune system and suppress autoimmune problems."

Nutrition For Women

Women's testosterone levels reach their peak during ovulation.

"On one day each month, during ovulation, women normally produce considerable amounts of testosterone."

Nutrition For Women

Testosterone deficiency and symptom relief in Parkinson's disease

"Men with Parkinson's disease have been found to have a deficiency of testosterone, one of the hormones involved in maintaining and repairing tissue, and supplementation with the hormone alleviates some of the symptoms."

March 2017 – Ray Peat's Newsletter

Testosterone decrease and estrogen increase due to stress

"In men, testosterone levels decrease due to stress and aging, and its conversion to estrogen is increased by stress and inflammation. Endotoxin specifically increases the conversion of testosterone to estrogen."

March 2017 – Ray Peat's Newsletter

Dihydrotestosterone might be more effective than testosterone

"Treatment with dihydrotestosterone (which cannot be converted to estrogen) could be more effective than with ordinary testosterone, taking into account the increased aromatase activity associated with age, stress and inflammation, as well as the likely role of estrogen in the excitatory degenerative process."

March 2017 – Ray Peat's Newsletter

Protective functions of progesterone in high-energy states

"During constructive exploration, energy is plentiful, and the cells with the highest energy requirements are protected by progesterone, testosterone, DHEA, and other steroids."

January 2018 – Ray Peat's Newsletter

The fundamental role of progesterone and DHEA

"Progesterone and DHEA are the precursors for the other, more specialized steroid hormones, including cortisol, aldosterone (the sodium-retaining hormone), estrogen and testosterone."

Generative Energy Restoring The Wholeness Of Life

Reversal of age-related skin changes and restoration of hair growth through steroids

“People who studied the effects of steroids on aging skin found that the steroids that reversed structural age-related changes in the skin (progesterone, testosterone, pregnenolone) sometimes restored hair growth.”

Generative Energy Restoring The Wholeness Of Life

Concerns about administering DHEA without a balanced hormonal system

"Since DHEA can be easily metabolized to testosterone (for example, through the skin) and to estrogen, I don't think it should ever be administered on its own – without a roughly natural balance of pregnenolone and progesterone."

Generative Energy Restoring The Wholeness Of Life

The different reactions of anti-estrogenic systems in the organism

"There are many anti-estrogenic systems (thyroid, progesterone, testosterone, sulfation, methylation, glucuronidation, anti-inflammatory factors, etc.), and the different, specific nature of the organism's response to stimulation is probably sufficient to explain the various outcomes, such as masculinity or femininity, swelling or growth, alertness or mania."

March 2000

Estrogen's controversial role in the treatment of prostate cancer

"Since it was known that estrogen treatment is dangerous for men and increases blood clotting and vascular spasms, there must have been some overarching belief that led to its widespread use in the treatment of prostate cancer. This belief seems to be that estrogen, the female hormone, counteracts testosterone, the male hormone, which is responsible for the growth—and thus the development—of the prostate. Everything about this statement is wrong, but every part of this belief can be found in the medical literature: present and effective."