Multiple longitudinal studies have estimated that between 20% and 50% of men have low serum testosterone, leading to symptoms such as decreased energy, decreased libido, erectile dysfunction, and changes to mood and cognition. Though weight loss has been implicated in moderating serum testosterone levels, the role of specific diets is not well understood. It was found that men who followed a low-fat diet showed moderately lower serum testosterone levels than those following nonrestrictive diets, according to results published in Urology.

Data were gathered by the Centers for Disease Control and Prevention as part of 3 cycles of the US National Health and Nutrition Examination Survey (NHANES) between 1999 and 2012. The study population was composed of men aged between 18 and 80 years who had completed a 2-day dietary history. Researchers noted participant adherence to the American Heart Association low-fat diet and the Mediterranean diet. Based on macronutrient profiles consumed by patients over a 2-day period, men were grouped into either of these groups or were classified as having a nonrestrictive diet. The researchers analyzed covariables such as age, activity level, income, body mass index, and comorbidities. They also measured resulting levels of serum testosterone and classified patients as testosterone deficient using criteria created by the American Urological Association.

The researchers found that men who followed Mediterranean and low-fat diets were older on average and were more likely to have diabetes than their nonrestrictive diet counterparts. Additionally, those adhering to the diets were less physically active and more likely to have ≥1 comorbidities. Among participants, 26.8% were shown to be testosterone deficient. Following a univariable analysis, the researchers found that men who followed either the low-fat or Mediterranean diet had lower serum testosterone than those following nonrestrictive diets. When a multivariable analysis was performed, the researchers found no significant differences between the 2 groups.

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Due to the popularity of various restrictive diets, researchers note the importance of understanding unintended effects of eating patterns on personal health. Dieting for weight loss can aid in improving cardiovascular health but may result in unintended effects like lower serum testosterone. The current study was limited by several factors, including the cross-sectional nature of the data, the fact that dietary intake was self reported, and the possibility of cofounders among the covariates. The researchers note that because the mechanism of how diet affects serum testosterone levels is not fully understood, future studies are required to fill this gap in knowledge.


Fantus RJ, Halpern JA, Chang C, et al. The association between popular diets and serum testosterone among men in the United States. J Urol. 2020;203(2):398-404. doi: 10.1097/JU.0000000000000482. Epub 2019 Aug 8.