Study: Low Fat Diets Lower Testosterone Levels in Men

A new study conducted at the University of Worcester and published in the Journal of Steroid Biochemistry and Molecular Biology found that low-fat diets lower testosterone levels in men by 10-15%.

Optimal testosterone levels are critical to men’s health. Low testosterone levels are linked to a higher risk of heart disease, diabetes, and Alzheimer’s disease. Healthy testosterone levels are also important to men’s athletic performance, mental health, and sexual health.

Since the 1970s, the average testosterone level in men has decreased and the rate of hypogonadism (medically low testosterone levels) has increased. Low risk diet strategies could be a useful treatment for low testosterone levels.

The study was a systematic review and meta-analysis that combined the results of 6 well-controlled studies involving a total of 206 participants. These studies put men on a high-fat diet (40% fat) and then a low-fat diet (20% fat) and found that their testosterone levels decreased by 10-15% on average. Vegetarian low-fat diets, which resulted in a decrease in testosterone by up to 26%, were particularly bad.

The authors linked their results to similar studies in humans and mice. These studies found that high monounsaturated fat intake in olive oil, avocados, and nuts can increase testosterone production. However, polyunsaturated omega-6 fats, which are found predominantly in vegetable oils, can impair the cells’ ability to produce testosterone. This is because highly unsaturated fats, like polyunsaturated fats, are more prone to oxidation, which leads to cell damage.

“Low testosterone levels are linked to a higher risk of heart disease, diabetes and Alzheimer’s disease.”

The authors indicated that further research needs to be carried out in this important area.

Ideally, we would like to see more studies to confirm our results. However, these studies may never be done. Usually, researchers want to find new results, not replicate old ones. In the meantime, men with low testosterone levels should avoid low-fat diets. “

Joseph Whittaker, senior researcher

Dietary fat is a controversial topic in nutritional science, with proponents of different diets often in strong disagreement (low fat versus low carbohydrate). The benefits of a low-fat diet like lowering cholesterol should be weighed against the possible disadvantages like lowering testosterone levels.

Traditionally, dietary guidelines have focused on limiting fat intake, with current UK and US guidelines restricting fat intake to less than 35% of total calories. However, with more research into the benefits of a high-fat, low-carb diet, this traditional view is increasingly being scrutinized. In the past few years, high fat diets have been shown to lower triglycerides, lower blood pressure, increase HDL cholesterol (also known as “good cholesterol”) and now with this latest research: increase testosterone levels.


Journal reference:

Whittaker, J & Wu, K (2021) Low Fat Diet and Testosterone in Men: Systematic Review and Meta-Analysis of Interventional Studies. The Journal of Steroid Biochemistry and Molecular Biology.

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