Testosterone and Low Fat Diets

Low fat diets decrease testosterone levels in men

A new study conducted at the University of Worcester and published in The Journal of Steroid Biochemistry and Molecular Biology, has found that low fat diets decrease testosterone levels of men by 10 to15%.

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 key for men’s athletic performance, mental health, and sexual health.

Since the 1970s, there has been a decrease in the average testosterone levels of men, and as a result, rates of hypogonadism (medically low testosterone) have been increasing.

The study conducted at the University of Worcester included a systematic review and meta-analysis, which combined the results of six well-controlled studies including 206 participants. During these studies, the participating men first followed a high-fat diet (40% fat), and then moved to a low-fat diet (20% fat). The results indicated that their testosterone levels decreased by 10 to 15% on average when following the low-fat diet. The most pertinent results were found where vegetarian low-fat diets caused a decrease in testosterone levels of up to 26%.

The authors linked their results to similar studies conducted in humans and mice. These studies found that high intakes of monounsaturated fats present in olive oil, avocados, and nuts may boost testosterone production. However, Omega 6 polyunsaturated fats predominantly found in vegetable oils, may damage the ability of the cells to produce testosterone. This is because highly unsaturated fats such as polyunsaturated fats are more prone to oxidation, which causes cell damage.

The authors stated that low testosterone levels are linked to a higher risk of heart disease, diabetes, and Alzheimer’s disease and that further research needs to be done in this important area. The lead researcher, Joseph Whittaker, said, “Ideally, we would like to see further studies to confirm our results. However, these studies may never happen since researchers normally want to find new results, not replicate old ones. In the meantime, it would be wise for men with low testosterone levels to avoid low-fat diets”.

Dietary fat is a controversial topic in nutritional science, with supporters of various diets often in stark disagreement (low fat vs. low carbohydrate). The benefits of low-fat diets such as reduced cholesterol levels, should be weighed up against the potential downsides, such as decreased testosterone levels.

Traditionally, dietary guidelines have focused on limiting fat intake, with the current guidelines from the United Kingdom and United States limiting fat intake to less than 35% of total calories. However, as more research on the benefits of high fat vs. low carbohydrate diets is done, this traditional view is coming under increasing scrutiny. In recent years, high-fat diets have been shown to decrease triglycerides, decrease blood pressure, increase HDL cholesterol (aka ‘good cholesterol’), and now with this latest research, increase testosterone levels.