Ray Peat on Testosterone

January 29, 2026

The Stability of Testosterone and 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 (less goiter, migraine, etc.) but lower adaptability in the long term (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 a 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. Substances that counteract estrogen include dopamine and nickel, prolactin inhibitors; chalones, tissue-specific proteins that inhibit cell division (and possibly short-lived memory peptides); 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 Effects on Male Behavior

“Stress leads to an increase in estrogen and a loss of anti-estrogens such as thyroid, progesterone, and (in men) testosterone. Male primates who are bullied have reduced testosterone levels, and this effect persists long after their environment improves. The stress of submission seems to lead to an adjustment toward passivity. Their passivity prevents further injury, but we do not know how stressful their continued subordination is.”

Nutrition For Women

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

“Energetically, the estrogen-dominant metabolic state is less efficient than the oxidative state dominated by the thyroid and progesterone (or testosterone). The estrogen state is – similar to the state of learned helplessness in rats – parasympathetic, in that many chemical balances 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 Effects on Libido

"Normally, the liver treats estrogen like a toxin and removes it immediately from the body. When 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 opposes progesterone and testosterone, I think the pill could reduce libido by counteracting these other hormones."

Nutrition For Women

Glucose and hormones to relieve schizophrenia symptoms

"Pfeiffer studied the relationship of porphyria to certain forms of schizophrenia, but I don't believe he mentioned that a good dose of glucose or an anti-estrogenic hormone like testosterone or progesterone will 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, so it can also be used in men. It (or its precursor pregnenolone) has been used for prostatitis, arthritis, and infertility in men. Large amounts would likely suppress LH and reduce testosterone synthesis, but a smaller amount (especially in older men) seems to increase sperm count and motility. In male and female athletes who become infertile, it generally appears to be the appropriate therapy, usually combined with thyroid treatment."

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 never had them before. A summer in Alaska, with an unusually long day, can relieve symptoms in a chronically affected person. Dark, cloudy winters in England or the Pacific Northwest are strong stressors and lead to lower progesterone in women and testosterone in men."

Nutrition For Women

Effects of stress on thyroid and hormones

"Stress inhibits the thyroid and can lower progesterone (and/or testosterone) while increasing estrogen. Recent work by Siiteri and his group shows 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 by testosterone and progesterone

"Some of the changes of aging are probably related to autoimmune reactions, where the body attacks itself; both testosterone and progesterone normalize the immune system and suppress autoimmune issues."

Nutrition For Women

Women's testosterone levels peak during ovulation

"On one day of the month, during ovulation, women usually 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 tissue maintenance and repair, and supplementation with the hormone alleviates some of the symptoms.”

March 2017 – Ray Peat's Newsletter

Testosterone Decline and Estrogen Increase Due to Stress

“In men, testosterone decreases 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) might be more effective than with regular testosterone, considering the increased aromatase activity 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 Energy-Rich States

“During constructive exploration, energy is abundant, and the cells with the highest energy demand 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

Reversing Age-Related Skin Changes and Restoring Hair Growth with 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 Balanced Hormone Levels

“Since DHEA can easily be metabolized into testosterone (for example through the skin) and estrogen, I don’t think it should ever be given alone – without an approximately natural balance of pregnenolone and progesterone.”

Generative Energy Restoring The Wholeness Of Life

The Different Responses of Anti-Estrogen Systems in the Body

“There are many anti-estrogen systems (thyroid, progesterone, testosterone, sulfation, methylation, glucuronidation, anti-inflammatory factors, etc.), and the different, specific way the body responds to stimulation is probably sufficient to explain the various outcomes, such as masculinity or femininity, swelling or growth, alertness or mania.”

March 2000

The Controversial Role of Estrogens in the Treatment of Prostate Cancer

"Since it was known that estrogen treatment is dangerous for men and increases blood clotting as well as vascular spasms, there had to be some overriding belief that led to its widespread use in treating prostate cancer. This belief seems to be that estrogen, the female hormone, opposes testosterone, the male hormone, which is responsible for the growth – and thus the cancer development – of the prostate. Everything about this statement is wrong, but you can find every part of this belief in the medical literature: present and effective."