Intermittent Fasting May Help With PCOS Weight Loss

Polycystic ovary syndrome (PCOS) is a common hormonal condition that can make weight loss especially challenging. Many people with PCOS experience what’s often called “weight-loss resistance,” meaning traditional approaches like calorie counting don’t always lead to expected results. Because of this, researchers are increasingly exploring alternative strategies that may better support weight management in this population.

“We’re looking for other ways of lowering testosterone levels in these women,” said lead investigator Krista Varady, Ph.D., professor of nutrition at the University of Illinois, Chicago. “One way is through weight loss. If someone loses around 5% of their body weight, they can actually help lower testosterone levels and sidestep any kind of drug intervention.”

One approach gaining popularity is time-restricted eating (TRE), also known as intermittent fasting. This method focuses on when you eat rather than how much you eat. Instead of counting calories, individuals limit their meals to a specific daily window. In this study, published in Nature Medicine, participants followed a six-hour eating window (consuming all meals between 1 p.m. and 7 p.m.) without tracking calories.

A team of investigators compared TRE with two other approaches: a traditional calorie restriction (CR) plan (reducing daily calories by 25%) and a control group that made no dietary changes. The study included 76 premenopausal women with PCOS and lasted six months.

The results showed that both TRE and calorie restriction led to meaningful weight loss. Participants using TRE lost an average of 4.32% of their body weight, while those in the calorie restriction group lost about 4.66%. This equated to a loss of about 10 pounds during the six-month period, and both groups cut about 200 calories per day. Importantly, there was no significant difference between the two approaches, meaning TRE worked just as well as traditional calorie cutting. Meanwhile, the control group did not experience similar weight changes.

This is especially important for patients who find calorie counting difficult or unsustainable. TRE may offer a simpler, more flexible option that still delivers results. Instead of focusing on tracking every bite, patients can concentrate on maintaining a consistent eating schedule.

The study also found that TRE was safe and well tolerated, with no serious adverse events reported. That’s reassuring, particularly for patients concerned about trying a newer or less traditional approach.

Both groups saw a drop in overall testosterone levels, but intermittent fasting showed some additional benefits. Only the TRE group experienced a reduction in the free androgen index, a key measure of how much active testosterone is available in the body. This suggests the approach may have a greater impact on hormone activity, not just hormone levels. Participants following intermittent fasting also showed improvements in A1c, an important marker linked to diabetes risk.

However, TRE did not significantly improve other common symptoms of PCOS, such as irregular menstrual cycles. Varady noted that these symptoms may take longer to improve and could require more weight loss or extended adherence to the diet.

Encouragingly, the approach appeared sustainable for many participants: About 80% of those in the TRE group said they planned to continue with it, suggesting it may be a manageable long-term option for some patients.

“There’s a particular sentiment that intermittent fasting is really bad for women,” Varady said. “This study and several other studies published by our lab and others show that intermittent fasting can actually improve female hormone levels, particularly in women with PCOS.”