The effects of calorie restriction on testosterone levels depend on baseline body composition Original paper

Testosterone levels in men decline with age, and approximately 24% of men aged 30 to 79 have low testosterone.^[1] Studies examining the effect of diet on testosterone levels have produced mixed results, which may be due to a range of factors, including the health status of the cohort, the number of calories that are restricted, and the composition of the foods consumed. Therefore, a systematic evaluation of the evidence is needed to tease out the effect of diet on testosterone levels.

This meta-analysis of 5 randomized controlled trials investigated the effect of calorie restriction on testosterone levels in men. The duration of the interventions varied from 1 week to 2 years.

Calorie restriction increased average testosterone levels (large effect size). In the subgroup analyses, calorie restriction did not affect testosterone levels in participants with normal weight, but there was an enhanced positive effect in participants with overweight or obesity.

This meta-analysis is limited by a small number of studies and substantial heterogeneity in the data, which is likely explained by large variation in participant ages, BMIs, energy intakes and deficits, and study duration.

Although the meta-analysis reported that calorie restriction did not affect testosterone concentrations overall in participants with normal weight, of the 3 studies included, 2 reported significant decreases in total testosterone concentrations. There were also 2 studies included in the systematic review (but not the meta-analysis) that found that calorie restriction reduced testosterone levels in athletes, which lends support to the idea that calorie restriction largely reduces testosterone levels in healthy men with normal weight.