Body fat percentage may be a better indicator of male reproductive health than body mass index (BMI), according to a new study reported by Healthline.
Researchers found that a higher body fat percentage was linked to lower sperm counts and changes in male sex hormone levels, including testosterone. They noted that these links held true even among men with a normal BMI but an elevated body fat percentage.
What researchers found in men with high body fat
Men with a high percentage of body fat generally had a lower total sperm count, a smaller ejaculate volume and a lower sperm concentration, the study found.
The study examined 1,058 Danish men aged 18 years and 9 months using a bioimpedance analyzer, which measures levels of body fat, water and muscle mass. Participants were split into four categories based on body fat percentage: low (under 8%), normal (8 to 19%), high (20 to 24%) and very high (25% or more).
Researchers also measured BMI and waist-to-height ratio. Participants provided semen and blood samples, had their testicular size measured and completed a lifestyle questionnaire.
Sperm counts dropped by up to 23%
Men with a high level of body fat had, on average, a 23% lower sperm count compared with those whose levels fell within the normal range. Men with a very high level of body fat had a sperm count 15% lower than men with normal levels.
The high body fat group also showed lower levels of sex hormone-binding globulin (SHBG) and testosterone, along with changes in the balance of male reproductive hormones, the researchers found.
Sperm count linked to lifespan in other research
Other studies have shown that men who produce more than 120 million motile sperm per ejaculation live on average two to three years longer than men with a count below 5 million, according to the report.
