For the study published in the Journal of Urology, men diagnosed with testosterone deficiency were examined.
While weight-loss may be associated with increased testosterone levels, practicing a low-fat diet may result in a small but significant reduction in testosterone, reveals the latest study. For the study published in the Journal of Urology, men diagnosed with testosterone deficiency were examined.
"We found that men who adhered to a fat restrictive diet had lower serum testosterone than men on a nonrestrictive diet," said study researcher Jake Fantus from the University of Chicago in the US.
"However, the clinical significance of small differences in serum T across diets is unclear," Fantus added.
The team analyzed data on more than 3,100 men from a nationwide health study (the National Health and Nutrition Examination Survey, or NHANES). All participants had available data on diet and serum testosterone levels.
The findings based on a two-day diet history revealed that 14.6 percent of men met criteria for a low-fat diet, as defined by the American Heart Association (AHA). 24.4 percent of men followed a Mediterranean diet rich in fruits, vegetables, and whole grains, but low in animal protein and dairy products.
Since only a few men met the criteria for the AHA low-carbohydrate diet, this group was excluded from the analysis.
The average serum testosterone level was 435.5 ng/dL (nanograms per deciliter). According to the study, serum testosterone was lower in men on the two restrictive diets: average 411 ng/dL for those on a low-fat diet and 413 ng/dL for those on the Mediterranean diet.
The researchers adjusted for other factors that may impact testosterone secretion such as age, body mass index, physical activity, and medical conditions.
After all, adjustments were made, the team concluded that a low-fat diet was significantly associated with reduced serum testosterone, although the Mediterranean diet was not.
Overall, 26.8 percent of men had testosterone levels less than 300 ng/dL. Researchers also pointed that despite the difference in average testosterone levels, the proportion of men with low testosterone was found to be similar across all diet groups.
Researchers highlighted the need for further investigation to find the direct causal effect of diets on testosterone levels.
Due to the difficulties of large-scale dietary studies, definitive trials are unlikely to be performed, they noted.
"Therefore, our data represent a valuable approach towards answering this important question," the researchers concluded.