Losing weight alone won’t boost pregnancy chances, study says

CHARLOTTESVILLE, Va. — If an obese woman is struggling to become pregnant, it’s common for doctors to suggest losing some weight. Unfortunately, a new study finds losing weight alone fails to provide any fertility benefits. Importantly, however, exercise regardless of weight loss does appear to offer some fertility upsides.

Study authors from the University of Virginia Health System analyzed a group of 379 obese women experiencing unexplained infertility. To their surprise, even when the ladies implemented intensive lifestyle changes that led to weight loss, their chances of pregnancy and a healthy birth did not improve any more than it would have by simply increasing physical activity without actually losing weight.

“We have known for decades that obese women often have difficulty getting pregnant,” says researcher Daniel J. Haisenleder, PhD, from the University of Virginia School of Medicine’s Center for Research in Reproduction, in a university release. “For this reason, many physicians advise weight loss prior to conception. However, there are few studies that have addressed the issue comparing a healthy lifestyle – i.e., exercise – vs. exercise plus weight loss.”

Fertility relies on diet and exercise

This research project took place at nine academic medical centers across the United States, with participants separated into one of two groups. Half of the participating women exercised more, stuck to a strict diet, and took their prescribed medications. The other half only exercised more and didn’t worry specifically about losing weight. After this stage, all participants received three rounds of standard infertility treatments.

Women who dieted and exercised ended up losing roughly seven percent of their body weight, while those who only exercised didn’t lose any weight. Notably, the team did not record a significant difference between the two groups regarding healthy birth frequency. More specifically, while 23 out of the 188 women assigned to the 16-week diet and exercise program gave birth to a healthy new baby. A similar portion of women instructed to only exercise did the same (29 out of 191).

Besides pregnancy considerations, losing weight did offer the women other health benefits. Women who lost weight enjoyed a big drop in metabolic syndrome, which is a combination of conditions known to increase the risk of health issues such as diabetes, stroke, and heart disease.

All in all, study authors conclude that losing weight specifically did very little to improve the women’s pregnancy odds.

“Weight loss improved metabolic health in these subjects. Unfortunately the changes seen did not improve fertility,” Dr. Haisenleder concludes. “Infertility within this population remains an important health issue, and will require further studies to address the problem in the future.”

The study is published in PLoS Medicine.