Evaluating the impact of obesity on male fertility

This study looked at the effect of obesity on sperm quality and erectile dysfunction (ED) among men in infertile couples. They found obese men had lower sperm quality and were more likely to have ED.

Obesity has many effects on the body, including changing hormone levels, increasing the temperature of the scrotum in men, and increasing inflammation. These factors may affect semen quality. Also, obesity can affect heart health. Problems with heart function and blood flow may lead to ED. The effect of body weight on semen quality and ED is not well studied in men with infertility.

This study involved 3,174 men whose partners had not conceived after 1 year of regular unprotected sex. The men were grouped according to their body mass index (BMI; a measurement of body weight in relation to height). 38 men were underweight (BMI lowed than 18.5 kg/m²), 1,803 had a normal weight (BMI=18.5 – 24.9 18.5 kg/m²), 1,161 were overweight (BMI=25 – 29.9 18.5 kg/m²), and 172 were obese (BMI higher than 30 18.5 kg/m²). A semen sample was collected from all the men.

Overweight and obese men were significantly more likely to have a low volume of semen (fewer than 2 mL). High BMI also made it significantly more likely that sperm had low progressive motility. This means that fewer than 32% of the sperm moved normally. 59.9% of obese men and 55.2% of overweight men had sperm with low progressive motility, compared to 49.2% of normal-weight men. There were no differences in the concentration of sperm based on BMI.

The men’s ability to get and maintain an erection was measured by the IIEF-5 survey. A lower score translates into a lower probability to get an erection or ED. Obese men were significantly more likely to have a low IIEF-5 score than normal-weight men. 52.9% of obese men had a low score, compared to 43.1% of normal-weight men. 

This study concluded that among men with infertility, obese men were more likely to have a low volume of semen, fewer sperm that moved normally, and ED.

Only a single semen sample was collected from each man. The quality of semen can vary between several samples. Also, some indicators of male infertility were not measured, such as sperm morphology (shape).

Talk to your doctor about lifestyle factors such as diet and exercise and their effect on health, weight, and fertility.