Researchers tested a low-calorie ketogenic diet (a diet very low in carbs and high in fats) on 13 women with PCOS, a common hormone condition that affects weight and fertility. After just 4 weeks, women lost an average of nearly 7% of their body weight and saw improvements in their blood sugar, insulin levels, and cholesterol. The diet also changed important hormones related to PCOS. While these short-term results look promising, the study was small and only lasted a month, so more research is needed to see if these benefits last longer.

The Quick Take

  • What they studied: Whether a low-calorie ketogenic diet (eating very few carbs and lots of healthy fats) could help women with PCOS lose weight and improve their hormone and blood sugar levels
  • Who participated: 13 women with PCOS who were overweight or obese, averaging 30 years old. All had the condition that causes irregular periods, excess hair growth, and fertility problems
  • Key finding: Women lost about 7% of their body weight in just 4 weeks. Their blood sugar control improved, their insulin levels dropped, and important hormones changed in ways that suggest the diet helped their PCOS symptoms
  • What it means for you: If you have PCOS and are overweight, this diet might help you lose weight and improve your hormone levels fairly quickly. However, this was a very short study with a small group, so talk to your doctor before trying it. The long-term safety and effectiveness aren’t yet proven

The Research Details

This was a short-term intervention study, meaning researchers had women follow a specific diet and measured what happened to their bodies and blood work. Thirteen women with PCOS followed a low-calorie ketogenic diet for 4 weeks. Before and after the diet, researchers measured their body weight, body fat percentage, waist and hip measurements, and took blood samples to check hormone and blood sugar levels. The ketogenic diet is very low in carbohydrates (like bread, pasta, and sugar) and high in fats and proteins, which forces the body to burn fat for energy instead of carbs.

PCOS is a condition where women’s bodies don’t respond well to insulin (the hormone that controls blood sugar), which causes weight gain, irregular periods, and fertility problems. Finding a diet that quickly improves insulin sensitivity and helps with weight loss could be really helpful for women with this condition. This study looked at whether the ketogenic diet could do this in a short time frame

This study has some important limitations to understand: it was very small (only 13 women), lasted only 4 weeks (too short to know if benefits last), and had no control group to compare against (so we don’t know if other diets work just as well). The journal is a respectable nutrition publication, but the small size and short duration mean we should be cautious about the results. More research with larger groups and longer time periods is definitely needed

What the Results Show

Women lost an average of 6.9% of their body weight in 4 weeks, which is a significant amount for such a short time. Their body mass index (BMI, a measure of weight relative to height) decreased, and they lost both fat and some muscle. Measurements of their waist, hips, and neck all got smaller. These physical changes were all statistically significant, meaning they were real changes and not just random variation.

The diet also improved several important blood markers. Fasting blood sugar (glucose) levels dropped, meaning their bodies were better at controlling blood sugar. Insulin levels decreased, which is important because high insulin is a key problem in PCOS. A measure called HOMA-IR, which shows how well the body responds to insulin, also improved significantly. These changes suggest the diet helped their bodies use insulin more effectively.

The diet caused some interesting changes in hormones and other blood markers. A hormone called SHBG (which helps control sex hormones) increased, which is generally good for PCOS. Prolactin levels decreased. However, inflammation markers (TNF-alpha) actually increased slightly, which is not ideal. HDL cholesterol (the ‘good’ cholesterol) decreased, which is a concern. The researchers found that changes in body measurements, especially waist and hip size, were connected to changes in prolactin levels, and changes in body fat were connected to changes in SHBG

Other studies have shown that ketogenic diets can help with weight loss and insulin sensitivity in people with PCOS, so these results fit with what researchers already suspected. However, most previous studies lasted longer than 4 weeks, so this study adds information about very quick initial changes. The finding about increased inflammation (TNF-alpha) is concerning and hasn’t been consistently reported in other PCOS diet studies, suggesting this might be a short-term effect or specific to this group

This study has several important limitations: Only 13 women participated, which is a very small group and makes it hard to be confident the results apply to all women with PCOS. The study only lasted 4 weeks, so we don’t know if women can stick with this diet or if the benefits continue over months or years. There was no comparison group (like women eating a regular diet), so we can’t be sure the ketogenic diet is better than other approaches. The study didn’t track whether women had any side effects or difficulty following the diet. Finally, the women in the study were all overweight or obese, so results might not apply to women with PCOS who are at a normal weight

The Bottom Line

If you have PCOS and are overweight, a low-calorie ketogenic diet may help you lose weight and improve your insulin sensitivity relatively quickly (moderate confidence based on this small study). However, you should only try this diet under medical supervision, especially if you take medications for PCOS or diabetes. The increased inflammation marker is a concern that needs more investigation. This diet is very restrictive and difficult for many people to follow long-term, so discuss with your doctor whether it’s right for you and whether other approaches might work better

Women with PCOS who are overweight or obese and want to lose weight quickly might benefit from this information. Women with PCOS at normal weight probably won’t see the same results. People with diabetes, heart disease, or high cholesterol should be especially cautious and get medical approval first. This diet is not recommended for pregnant women or those trying to become pregnant without medical supervision. Anyone with a history of eating disorders should avoid very restrictive diets like this

Based on this study, you might see weight loss and improvements in blood sugar control within 4 weeks. However, it’s unclear how long these benefits last if you continue the diet, or whether they fade if you stop. Most people need at least 8-12 weeks to see if they can stick with a diet long-term, so that’s a more realistic timeline for deciding if this approach works for you

Want to Apply This Research?

  • Track daily carbohydrate intake (aim for under 50 grams per day) and weekly body weight and waist circumference measurements. Also monitor energy levels and any side effects like fatigue or digestive issues
  • Start by identifying and removing high-carb foods (bread, pasta, rice, sugar, most fruits) and replacing them with healthy fats (olive oil, avocados, nuts) and proteins (eggs, fish, chicken). Use the app to log meals and stay under your carb target each day
  • Weekly weigh-ins and waist measurements to track progress. Monthly blood work (if approved by your doctor) to monitor glucose, insulin, and cholesterol levels. Track how you feel daily, including energy, mood, and any PCOS symptoms like irregular periods or excess hair growth

This research describes a short-term dietary intervention in a very small group of women. The findings are preliminary and should not be considered definitive medical advice. Before starting a ketogenic diet, especially if you have PCOS, diabetes, heart disease, or take medications, consult with your doctor or a registered dietitian. This diet may not be appropriate for everyone, and individual results vary significantly. The study’s short duration means long-term safety and effectiveness are unknown. This information is for educational purposes only and does not replace professional medical guidance.