Keto may help some women with polycystic ovary syndrome (PCOS), mainly by aiding weight loss and improving insulin resistance, but the evidence is still limited and no single diet has been shown to work best. A 2023 meta-analysis found that women with PCOS who followed a ketogenic diet for at least 45 days had lower free testosterone, a better balance of reproductive hormones and more weight loss, but the trials were small and short. The 2023 international PCOS guideline concludes that there’s no evidence to support one type of diet over another, and recommends a healthy eating pattern you can maintain. Keto is one option to discuss with your doctor, alongside other diets and medical treatments.
What is PCOS?
PCOS is a common hormonal condition that affects how the ovaries work. Symptoms can include irregular or absent periods, difficulty getting pregnant, excess facial or body hair, acne, thinning hair and weight gain. Many women with PCOS have insulin resistance, meaning the body needs more insulin to keep blood sugar normal. High insulin levels can increase the ovaries’ production of testosterone, which drives many symptoms. The NHS explains the condition and how it’s diagnosed.
Why low-carb diets are used for PCOS
Because insulin resistance plays a central role, diets that lower blood sugar and insulin levels make sense in theory. Cutting refined carbs and sugar reduces the insulin response to meals. Weight loss also helps: losing even a modest amount of weight can make periods more regular and improve insulin resistance in women who are overweight. Our guide to keto and insulin resistance explains the link.
What the evidence shows
Small studies of keto
In an early pilot study, 11 women with PCOS were asked to eat 20 g of carbs or less a day for 24 weeks. Only 5 finished, but they lost 12% of their body weight on average, and their free testosterone fell by 22%. The 2023 meta-analysis pooled several small trials and found improvements in the LH to FSH ratio, free testosterone and sex hormone binding globulin, along with weight loss. Most trials lasted only a few months, many didn’t have a comparison diet, and the women were mostly overweight, so it’s hard to know whether keto itself or weight loss explains the results.
What the guideline says
The international guideline, developed by experts from many countries and endorsed by medical societies, recommends healthy lifestyle changes for all women with PCOS. It says there’s no evidence that any particular diet composition works better than others for weight, reproductive, metabolic or emotional outcomes. Choosing an eating pattern you can stick with matters most.
Possible benefits of keto for PCOS
- Weight loss, which can improve periods, fertility and insulin resistance.
- Lower insulin and blood sugar after meals.
- Lower testosterone in some women, which may help with acne and excess hair over time.
- Fewer sugar cravings for some people.
Possible downsides
- Hard to sustain. Many women find strict keto difficult long term, and weight regain is common.
- Nutrient gaps: keto can be low in fiber, folate, calcium and some vitamins, which matters especially if you’re trying to conceive.
- LDL cholesterol rises in some people. Women with PCOS already have a higher risk of heart disease, so cholesterol should be checked. Our guide to keto and cholesterol explains more.
- Disordered eating: women with PCOS have higher rates of eating disorders, and restrictive diets can make this worse.
- Pregnancy: keto isn’t recommended in pregnancy without specialist advice. If keto helps you conceive, talk to your doctor about changing your diet once you’re pregnant. Our guide to keto during pregnancy explains why.
Alternatives that may help
- A moderate lower-carb diet that keeps whole grains, beans and fruit in controlled portions.
- A Mediterranean-style diet, rich in vegetables, olive oil, fish, nuts and legumes. Our guide to Mediterranean keto combines both approaches.
- A low glycemic index diet, which focuses on slower-release carbs. Our guide to the glycemic index explains how.
- Regular physical activity, which improves insulin sensitivity regardless of weight loss.
If you want to try keto for PCOS
- Talk to your doctor first, especially if you take metformin, the contraceptive pill or other medicines, or are trying to conceive.
- Build meals around vegetables and protein, with olive oil, nuts, avocado and oily fish as your main fats.
- Take folic acid if there’s any chance of pregnancy, as the NHS advises for all women trying to conceive.
- Track your periods, weight and symptoms to see what changes.
- Get blood tests before and after a few months, including cholesterol and blood sugar.
- Reassess after 3 months. If it isn’t helping or is hard to sustain, a more flexible approach may be better.
Our guide to how to start keto covers the basics.
Common questions
Can keto get rid of PCOS?
No. PCOS is a lifelong condition. Diet can help manage symptoms, but it doesn’t make PCOS go away.
Can keto help me get pregnant with PCOS?
Weight loss can improve ovulation in women with PCOS who are overweight. Some women conceive after changing their diet, but evidence that keto works better than other weight-loss approaches is lacking. Talk to your doctor about all your options.
Is keto safe with metformin?
Many women take both, but cutting carbs may affect blood sugar and digestion. Ask your doctor before starting.
What should I eat for PCOS if keto isn’t for me?
A balanced diet built on vegetables, fruit, whole grains, beans, lean protein and healthy fats, with fewer refined carbs and sugary drinks, is a good fit for PCOS. Choose foods you enjoy and can keep eating long term, and combine diet with regular activity.
Safety note: Keto isn’t suitable for everyone. If you have diabetes, kidney or liver disease, take regular medication, or are pregnant or breastfeeding, talk to your doctor before cutting carbs this far (why it matters).
This article is general information, not medical advice. Talk to your doctor or a registered dietitian before making big changes to how you eat, especially if you have a health condition, take regular medication, or are pregnant or breastfeeding.
