Excess weight may affect sperm production, reduce fertility in men

A new study co-authored by Jorge Chavarro, assistant professor of nutrition and epidemiology at Harvard School of Public Health (HSPH), finds that overweight and obese men are more likely than their normal-weight peers to produce lower numbers of sperm, or even no sperm at all. This could increase the likelihood that they would have difficulty conceiving. While the results don’t prove that excess weight leads to fertility troubles, having a lower sperm count can make it more difficult for men to conceive.

The researchers combined data from 14 studies comparing sperm count in overweight, obese, and normal-weight men, along with data from an infertility center. They found that overweight men were 11 percent more likely to have a low sperm count and 39 percent more likely to have no sperm in their ejaculate. Obese men were 42 percent more likely to have a low sperm count than their normal-weight peers and 81 percent more likely to produce no sperm. More research is needed to determine whether excess weight caused the low sperm count or if other underlying health problems were to blame.

However, Chavarro told Reuters Health, “This appears to be yet another health outcome for which maintaining a healthy weight appears to be important.”

The study appeared in the March 2012 Archives of Internal Medicine. Read abstract