Infertility is a growing public health concern, and poor semen quality plays a role in as many as 70% of all infertility cases. A recent review and meta-analysis found that men with obesity had lower semen volume, sperm number, and motility and fewer normal-shaped sperm than men with healthy body weight.

The reviewers analyzed the findings of studies investigating links between body mass index (BMI) and semen quality. Their analysis included 50 studies involving more than 71,000 men.

They found that compared to men with a healthy BMI, men with obesity had lower semen volume, sperm number, and motility and fewer normal-shaped sperm. These reductions in semen quality were more pronounced among the men with the highest BMIs. Men with overweight had lower semen volume and motility than healthy-weight men.

These findings suggest that excess body fat reduces semen quality, potentially contributing to infertility. Many other factors influence semen quality, including age, lifestyle factors (such as smoking, excess alcohol consumption, and poor sleep quality), and environmental exposure (such as air pollution, extreme temperatures, and microplastic exposure).