WORCESTER, United Kingdom — Many people champion low-fat and vegetarian diets as the best ways to stay healthy, but is that really the case for men? A new study finds lowering fat also slashes male testosterone levels. The results can leave men choosing to go green with their diets suffering a loss of libido.
Researchers from the University of Worcester add the male sex hormone also protects against heart disease, diabetes, and Alzheimer’s. Results show vegetarian low-fat diets rank as the worst for men’s sexual health; decreasing testosterone by up to 26 percent.
These diets typically focus on fruits, vegetables, whole grains, legumes, nuts, and seeds. Such foods are rich in fiber and low in calories in comparison to meat and other animal products. Other low-fat diets cut this key chemical by 10 to 15 percent on average, according to the study.
“There were significant decreases in sex hormones on low-fat vs high-fat diets,” lead author and nutritional therapist Dr. Joseph Whittaker writes in The Journal of Steroid Biochemistry and Molecular Biology.
Testosterone levels rely heavily on what you eat
The findings reveal Europeans are particularly prone to the effects of these fashionable eating plans. Study authors looked at blood samples from over 200 men with an average age of 46.
“Low-fat diets appear to decrease testosterone levels in men,” Dr. Whittaker reports. “Men with European ancestry may experience a greater decrease in testosterone, in response to a low-fat diet.”
A normal testosterone range is 300 to 1,000 nanograms per deciliter (ng/dL), depending on the person’s age. Average levels have been falling for 50 years however, and diets offer a low risk strategy of raising them. Dr. Whittaker and co-author Kexin Wu pooled data from six earlier studies where participants first went on a diet of 40 percent fat.
Testosterone levels plunged after the group switched to a diet with half that amount of fat. Omega 6 polyunsaturated fats, predominantly found in vegetable oils, may damage a cell’s ability to produce testosterone. Dr. Whittaker explains that they are more prone to harmful oxidation.
“Ideally, we would like to see a few more studies to confirm our results. However, these studies may never come, normally researchers want to find new results, not replicate old ones. In the meantime, men with low testosterone would be wise to avoid low fat diets,” the lead researcher says in a statement to SWNS.
Where can you get the right fats to stay healthy?
Dietary fat is a controversial topic, with proponents of diets low in fats or carbohydrates often in stark disagreement.
“The benefits of low fat diets such as reduced cholesterol levels should be weighed against potential downsides – such as decreased testosterone,” Dr. Whittaker adds.
Guidelines in the U.K. and U.S. generally focus on limiting fat intake to less than 35 percent of total calories. However, as nutritionists do more work on high-fat and low-carb diets, this traditional view is coming under increasing scrutiny.
In recent years, high-fat diets have been shown to destroy harmful blood fats called triglycerides and reduce blood pressure. They can also increase “good” HDL (high-density lipoprotein) cholesterol. The latest study now suggests they increase testosterone as well.
Low-fat diets typically contain whole grain foods, lean meats such as skinless chicken, fish, fruits, and vegetables. While these are healthy choices, experts stress the importance of including fats in any diet, more common in meats, nuts, and dairy products like cheese and milk.
Men should ideally consume plenty of monounsaturated fats, which are found in olive oil, avocados, and nuts, to boost testosterone. Fat is an essential component of a healthy, balanced diet. Experts generally advise against overdoing consumption of saturated fats, common in butter, fatty meats, cakes, and pastries. Too much fat in your diet, especially saturated fats, can raise “bad” LDL (low-density lipoprotein) cholesterol – which also increases the risk of heart disease.
SWNS writer Mark Waghorn contributed to this report.