For women grappling with polycystic ovary syndrome (PCOS), a ketogenic diet offers a beacon of hope. By targeting insulin resistance, a core issue in PCOS, this dietary approach may alleviate symptoms and improve fertility.
Understanding PCOS
PCOS is a prevalent endocrine disorder affecting women of reproductive age, characterized by hormonal imbalances, irregular periods, and often, high androgen levels. This syndrome is frequently accompanied by weight problems, further complicating the health landscape for those affected. The prevalence of obesity in women with PCOS may be as high as 75%. PCOS is strongly associated with obesity. Diet-induced weight loss and insulin-sensitizing agents are shown to improve ovulation.
The Ketogenic Diet: A Primer
The ketogenic diet is a restrictive low-carb diet plan that focuses on low carbs, high fats, and a moderate amount of proteins. The ketogenic diet (KD) has garnered increasing attention for its ability to cause significant weight loss and improve metabolic syndrome, both of which are characteristics of PCOS. Typically, it consists of 70-80% fats, 10-20% protein, and 5-10% carbohydrates. The primary goal is to reduce carbohydrate intake to 20-50 grams per day, encouraging the body to produce ketones for energy. When carb intake drops significantly, usually below 50 grams per day, the body enters a state called ketosis. This causes insulin levels to fall and prompts the body to use fat as its primary energy source. Typical keto-friendly foods include eggs, avocados, leafy greens, cheese, nuts, and fatty fish like salmon and mackerel.
The PCOS-Keto Connection: Targeting Insulin Resistance
Insulin resistance is a key feature of PCOS, where the body's cells don't respond effectively to insulin. This can lead to elevated blood sugar and insulin levels, contributing to various PCOS symptoms. “The link between insulin resistance and PCOS is very well studied,” says Ula Abed Alwahab, MD, an endocrinologist at Cleveland Clinic. “If we are able to control insulin resistance, then we are able to reduce many of the PCOS symptoms and complications, including weight, diabetes, high blood pressure, heart disease, and infertility.”
The ketogenic diet's strength lies in its ability to improve insulin sensitivity. By drastically reducing carbohydrate intake, it lowers insulin levels, making cells more responsive to insulin’s effects. A meta-analysis including 170 women with PCOS on a KD for 45 days or more demonstrated reduced luteinizing hormone/follicle stimulating hormone ratio, reduced serum free testosterone, and increased sex hormone binding globulin.
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Fixing the Problem Rather Than Alleviating Symptoms
Dr. Abed explains that the traditional treatment route for PCOS is essentially to treat the symptom. If a patient has irregular periods, her doctor would treat her with birth control pills just to her regular period without focusing on the consequences of that, or how much weight she might gain. If the patient has infertility, she would be given fertility treatments even though they are not always successful because of the other problems associated with PCOS. Dr. Abed’s team aims to achieve all of the goals of women with PCOS, such as weight loss, regular periods or pregnancy with higher success rates. “We’re helping with weight,” says Dr. Abed. “But we are also trying to regulate periods without necessarily being on birth control pills, and to achieve pregnancy and eventually live birth with minimal complications.”
Potential Benefits of Keto for PCOS
Weight Loss and Improved Metabolic Profile
Many patients see weight loss results-which helps reduce PCOS symptoms-but women with PCOS see improvements because the problem in PCOS is carbohydrate/insulin resistance. The ketogenic diet (KD) has garnered increasing attention for its ability to cause significant weight loss and improve metabolic syndrome, both of which are characteristics of PCOS. Weight loss can significantly improve PCOS symptoms. A KD was found to improve weight along with metabolic and endocrine parameters such as serum testosterone, serum insulin, and luteinizing hormone/follicle stimulating hormone ratio.
Hormonal Balance and Fertility
Research has shown that women with PCOS who followed a keto diet for at least 45 days had lower testosterone levels and improved follicle-stimulating hormone (FSH) levels. By addressing the hormonal imbalances stemming from insulin resistance, the ketogenic diet may restore regular menstrual cycles and enhance fertility. The study used a convenience sample of 30 women with PCOS that followed the KD for at least 3 months. Approximately 92% of women who had irregular menstrual cycles had return of regular menstruation at 6 months and it was 100% at 15 months. Eighteen of the 30 women desired pregnancy. In this sub-cohort, 10 women (55.6%) achieved pregnancy. In a small case series, our group previously reported that the KD restored regular menses in all patients and achieved pregnancy in 50% of the cohort.
Reduced Inflammation
Chronic inflammation is linked to PCOS. The anti-inflammatory properties of certain keto-friendly foods (like fatty fish, nuts, and seeds) may offer additional benefits. The keto diet may reduce inflammation, positively impacting symptoms like acne and fatigue, which are often reported by women with PCOS.
Examining the Evidence: Studies on Keto and PCOS
Several studies have investigated the effects of the ketogenic diet on PCOS, yielding promising results.
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- A small study found that patients with obesity and PCOS who underwent KD for 24 weeks, had significant reductions in body weight (−12%), fasting insulin (−54%), percent free testosterone (−22%), and LH/FSH ratio (−36%). Two patients conceived despite previous infertility problems
- Same changes were demonstrated in another study involving 12 patients with PCOs and overweight who underwent KD for 12 weeks had significant reductions in body weight, BMI, fat body mass and visceral adipose tissue with slight reduction in lean body mass. Significant reductions in insulin, glucose, HOMA-IR, total cholesterol, triglycerides, LDL, LH/FSH ratio, LH, total and free testosterone, and DHEAS levels were observed. HDL, estradiol, progesterone and SHBG levels increased.
- The Cleveland Clinic study found that more than half of the participants trying to conceive became pregnant after following a keto diet. In another trial, women with PCOS who were not taking metformin, a common medication for diabetes, achieved a 100% pregnancy rate while on a keto diet.
- A more recent review published in 2025 found that very low-carb keto diets were more effective at restoring regular menstrual cycles than other dietary approaches.
- In a 12-week study of 14 women with PCOS, a keto diet high in plant foods (like low carb veggies) resulted in significantly lower blood sugar and insulin levels, as well as better insulin resistance scores - indicating higher insulin sensitivity.
- Finally, a 45-day study of 17 women with obesity and PCOS found that a keto diet reduced average blood sugar levels by 10 mg/dL and mean insulin levels by nearly 13 micro-IU/mL. Insulin resistance scores, which reflect increased insulin sensitivity, also improved.
Potential Drawbacks and Considerations
While the ketogenic diet offers potential benefits for PCOS, it's essential to acknowledge the potential downsides and challenges.
Nutrient Deficiencies
Cutting out whole food groups, like fruits and whole grains, can lead to vitamin and mineral deficiencies. This is particularly concerning for nutrients like B vitamins, magnesium, and fiber. Since whole grains and fruits are key sources of dietary fiber, constipation can become an issue on the keto diet.
Sustainability
Many people find keto difficult to maintain long-term, increasing the likelihood of "yo-yo dieting," which can worsen metabolic health. Switching back and forth between keto and a high-carb diet can cause blood sugar fluctuations and disrupt hormonal balance.
Impact on Cholesterol Levels
In some studies, researchers have found that following a keto diet increases cholesterol levels. This may be a concern for some people, especially those who already have high cholesterol levels
Contraindications
For instance, the keto diet’s strict rules are likely not appropriate for people with a history of eating disorders or disordered eating. Those with conditions like pancreatitis, liver disease, or fat-metabolism disorders should avoid it entirely.
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A Sample PCOS Keto Diet Plan
For those who decide to try a keto approach, having a clear plan in place is essential. Below is a sample 3-day keto-friendly meal plan designed to support women with PCOS. This plan includes meals that promote hormonal balance, reduce inflammation, and support metabolic health.
Day 1
- Breakfast: Scrambled eggs with avocado and smoked salmon
- Lunch: Grilled chicken Caesar salad (with olive oil-based dressing, no croutons)
- Dinner: Baked salmon with a side of sautéed spinach and garlic
- Snack: Greek yogurt with chia seeds and unsweetened coconut flakes
Day 2
- Breakfast: Keto pancakes made with almond flour and topped with unsweetened berries
- Lunch: Zucchini noodles with pesto sauce and grilled shrimp
- Dinner: Grass-fed beef burger (lettuce wrap) with a side of cauliflower mash
- Snack: Handful of mixed nuts (almonds, walnuts, and pecans)
Day 3
- Breakfast: Chia seed pudding made with unsweetened almond milk and topped with raspberries
- Lunch: Cobb salad with hard-boiled eggs, turkey, and avocado (olive oil vinaigrette)
- Dinner: Grilled chicken thighs with roasted Brussels sprouts and garlic butter
- Snack: Cucumber slices with guacamole
Tips for Success on a PCOS Keto Diet
- Balance your macros: Use a keto macro calculator to ensure you’re hitting the right balance of fats, proteins, and carbs for PCOS management.
- Plan meals in advance: Meal prep can help you avoid last-minute food choices that deviate from your plan.
- Monitor symptoms: Track changes in menstrual cycles, energy levels, and cravings to gauge the diet’s effectiveness.
- Consult a professional: Work with a registered dietitian familiar with PCOS to create a personalized plan that supports hormonal health.
Alternative Dietary Approaches
Alternatives to keto include the Mediterranean diet, low-glycemic index (GI) diets, and the DASH diet. Each of these focuses on whole foods and supports stable blood sugar levels without eliminating entire food groups.
The Importance of Professional Guidance
Using keto for fertility and PCOS relief is worth considering, but it should be tailored to your health needs and guided by a healthcare provider. If you decide to try keto to manage your PCOS, be sure to work closely with a healthcare professional so they can closely monitor your progress. A less restrictive low carb diet may offer similar benefits for PCOS while being easier to adopt long-term than a strict keto diet.