WEDNESDAY, Nov. 5, 2025 (HealthDay News) — Losing weight is considered one way to improve male fertility, but how guys drop pounds also matters, a new evidence review says.

Men who lost weight through diet and exercise did wind up with better sperm quality, even with modest weight loss, researchers recently reported in the journal Human Reproduction Update.

However, losing weight through bariatric surgery did not cause any notable positive changes to sperm quality, even though men lost substantial amounts of weight quickly, researchers found.

“Lifestyle changes are associated with modest improvements in sperm motility and morphology, even though the amount of weight lost was much smaller than surgical options,” lead researcher Andrew Peel of the University of Adelaide’s Freemasons Center for Men’s Health and Wellbeing in Australia said in a news release.

“This indicates that for men with obesity, whilst obesity has detrimental effects, reproductive success may be more dependent on optimizing nutrition and exercise rather than substantial weight loss alone,” he said.

For the new study, researchers analyzed data from 32 previous studies involving men with obesity 18 to 50 years old. The men were trying to lose weight through surgery, weight-loss medications, or diet and exercise programs.

“Previous research has shown that infertility rates are approximately 50% higher in men with obesity compared to men of a normal weight, with the condition associated with reductions in basic sperm parameters among other reproductive issues,” co-senior author Gary Wittert said in a news release. He’s a professor at the University of Adelaide Freemasons Center for Male Health and Wellbeing.

Results from the review indicate that as far as sperm quality is concerned, diet and exercise could be a better fertility booster than bariatric surgery.

In fact, some evidence suggested that surgery should have short-term negative effects on fertility, possibly due to nutritional deficiencies or increases in hormone disruption associated with rapid weight loss, researchers said.

The data on weight-loss medications was limited to studies on the use of the diabetes drugs metformin and liraglutide.

“There is an urgent need for research on newer weight loss drugs like Ozempic to see what impact they have on male fertility. This is even more pressing given the rising popularity of these medications,” senior researcher Nicole McPherson of the University of Adelaide’s Robinson Research Institute said in a news release.

“We are not only living at a time when obesity is considered to be an epidemic, but fertility levels are also at record lows,” she added. “There is a real knowledge gap when it comes to the best approach for men with obesity wanting to improve their fertility and we strongly advocate for more research in this area to establish optimal preconception recommendations for men.”

More information

The Mayo Clinic has more on male fertility.

SOURCE: University of Adelaide, news release, Oct. 27, 2025