Hormones and Performance - Testosterone

May 21, 2021

 by Thomas Sampson

Testosterone and Diet

Healthy testosterone levels are responsible for the maintenance and growth of muscle and bone tissue. Increases in muscular size are due to the effect of testosterone on protein synthesis. Exercise increases testosterone levels providing for a strong and fit body. As men age, testosterone levels drop but many of the positive body composition effects can be maintained via supplementation and exercise.

But…. there is another side to the hormone. Testosterone is a facilitator of prostate cancer. For aging males the question is often whether it is more expedient to try and elevate blood testosterone levels to build more muscle and maintain sex drive or to lower them to minimize the risk of prostate cancer.

Dietary Fat and Fiber

In one experiment, a low fat, high fiber diet combined with modest exercise resulted in less free testosterone as well as a slight drop in prostate stimulating antigen (PSA) - a measurable prostate protein that increases with cancer risk. On the other hand, elite hockey players who consumed a low fat high carbohydrate diet over 7 months had an elevation in their total and free testosterone, but their diet lacked fiber which might have made a difference in their testosterone levels. Also, they were professional, highly trained athletes. Higher levels of mono- and polyunsaturated fat in the diet have been connected to higher resting testosterone levels.


A research project with men ages 51-69 who ate 50% of their calories as meat protein resulted in stronger muscles in response to resistance training than in a group of similar aged vegetarians. Yet, another study found that men who ate a diet lower in protein and higher in unsaturated fats had higher resting testosterone levels. These studies suggest that perhaps meat protein needs to be in the diet for higher testosterone levels, but that it should be kept to a minimum. Most scientific literature seems to agree that eating a high protein, low carbohydrate diet can cause a man's testosterone levels to drop.

Nutritionists suggest that a man's optimal protein intake for successful health and testosterone benefits should be about 15% of daily calories. For an average sized man this could include two chicken breasts and a regular size can of tuna.

Soy Products

In men, replacing meat with soy protein as tofu in their diet slightly lowered testosterone levels. In Japanese men who eat a traditional diet high in soy products, testosterone levels correlated inversely with their soy intake. In other words, the more soy they ate, the lower their testosterone level.

Calorie Restriction

Calorie restriction by more than 15% will cause testosterone levels to drop. Therefore, cutting calories is a good idea to treat obesity to dodge its health-related diseases, but diminishing testosterone levels should also be considered especially in the aging male.

Licorice (!)

Research has shown that eating an average size serving (one movie sitting?) of natural black licorice sticks resulted in a drop in testosterone by 34%! The active ingredient in licorice is glycyrrhizic acid which has a very similar chemical structure to aldosterone - the adrenal cortex hormone responsible for regulating the body's blood pressure. It has also been reported that consumption of large amounts of licorice can raise blood pressure. The advice by this research team was to switch to Twizzlers, synthetic licorice.

Fat and Fiber

A diet low in animal fat and refined carbohydrates and rich in low glycemic index foods, unsaturated fatty acids and phytoestrogens was found to lower testosterone in women who had high levels of the hormone. Just cutting fat to less than 25% of calories and doubling the amount of fiber in the diet decreases serum testosterone in some women.
The amount of fat a woman has around her middle (visceral fat) has been associated with high testosterone levels. While it is important for a woman to have enough of this hormone, there are some risks associated with too much.

What does this all mean?

There are some things we can do nutritionally to keep Testosterone levels within an acceptable range. One of the best and easiest solutions as we always say is to simply EAT REAL FOODS! The less highly processed foods the better.

If low testosterone is something you think you suffer from consult with your health care provider.


Thomas Sampson CFL-3, USAW-2, Sports Nutritionist

International sports science association. Sports nutrition. 5th edition. 2018 carpinteria CA

Nancy Clarks Sports Nutrition Guidebook. 4th edition. 2008 champaign IL

International Sports Science Association. Hormones and Performance. 2019 carpinteria CA