THURSDAY, Aug. 6, 2026 (HealthDay News) -- For men, body fat percentage may be a better indicator of reproductive health than body mass index (BMI), according to a study published online July 29 in Human Reproduction.
Nis Brix, M.D., from Aarhus University in Denmark, and colleagues examined whether body fat percentage is associated with semen characteristics, testicular volume, and hormone levels in a cross-sectional study involving 1,058 men aged 18 years and 9 months during 2017 to 2019.
The researchers found that high (20 to 24 percent) and very high (≥25 percent) -- compared with normal (8 to 19 percent) -- body fat percentages were associated with lower total sperm count (−23 and −15 percent for high and very high, respectively) and with tendencies toward lower semen volume and concentration. For the remaining semen characteristics and testicular volume, no associations were observed. There was an association seen for a higher body fat percentage with lower sex hormone-binding globulin and testosterone levels and higher free androgen index, luteinizing hormone, and estradiol levels. For low body fat (<8 percent), the results were generally in the opposite direction but less consistent. Compared with BMI and waist-to-height ratio, the associations with total sperm count, semen volume, and semen concentration were stronger for body fat percentage.
"For men, maintaining a healthy body composition, not just a healthy body weight for height, may be important for fertility," Brix said in a statement. "For doctors, assessing body fat percentage in selected patients could help identify men at risk of reduced fertility who might otherwise be overlooked based on BMI alone."
One author disclosed having Eli Lilly and Novo Nordisk stocks.
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