What is PCOS?

Polycystic ovarian syndrome (PCOS) is one of the most common hormonal conditions in women, affecting about 1 in 10 in the UK. It is diagnosed on the basis of having at least two out of the following three symptoms:


1. Irregular or absent periods.

2. Signs of hyperandrogenism (too much male hormone, including testosterone) e.g. acne, excess facial and body hair, male-pattern baldness.

3. Polycystic appearance of the ovaries on ultrasound scan – this means lots of small ‘cysts’ on the ovaries which are actually underdeveloped eggs that the ovary was unable to release.

Aside from these symptoms, it is associated with a higher risk of fertility issues, type 2 diabetes, sleep apnoea and heart disease in the longer term.

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About 70 per cent of women with PCOS have a degree of insulin resistance, insulin being the hormone that regulates our blood sugar. The body makes more insulin to try and compensate, which causes the ovaries to produce lots of testosterone, which is the root of many of the symptoms. The exact cause of PCOS is not well understood but is likely to a be complex interaction between genetic susceptibility and environmental factors.

PCOS cannot be ‘cured’, but there are certainly things that you can do to try and improve your symptoms, which can successfully be used alongside, or in some women, instead of, traditional modern medicine.

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Woman with stomach cramps

How does diet affect PCOS?

The Royal College of Obstetricians and Gynaecologists’ guidelines for management of PCOS states: “It is recommended that lifestyle changes, including diet, exercise and weight loss, are initiated as the first line of treatment for women with PCOS for improvement of long-term outcomes.”

Weight loss in those who are overweight, weight management in those who are not, and reducing central adiposity (fat tissue around the stomach & hips) can help to reduce insulin resistance, which as mentioned is the driver of the hormonal imbalance that characterises the disease. Fat tissue also makes its own testosterone so it’s a way of reducing that, too.

While weight loss of even 5-10 per cent of total body weight has been shown to improve hormone profiles, menstrual regularity as well as long-term outcomes, the evidence to suggest how best to do this is lacking. The internet is unfortunately awash with ‘PCOS diets’, most of which are incredibly low in carbohydrates (typically 20-30g/day), which – although effective in achieving modest weight loss in the short-term – can be punishingly difficult to stick to, with results rarely maintained in the long-term.

The other concern regarding long-term use of a ketogenic diet is the low fibre content. Fibre is a nutrient that most of us don’t consume in large enough quantities, with low fibre intake correlated with worsening insulin resistance and higher androgen (male hormone) levels in women with PCOS.

Looking at the quality rather than quantity of carbohydrates is a more approachable and effective way of managing PCOS. Several randomised controlled trials have shown that a low glycaemic index (GI) diet for PCOS can be effective for weight loss, reducing abdominal fat and improving hormone profiles.

While this is all very ‘weight loss heavy’, I prefer not to make weight loss the emphasis with my patients. Not least because disordered eating is more commonly seen in women with PCOS, so it’s important for all healthcare professionals to take this into consideration when managing this group of women.

Nuts, avocado, salmon and other good fats

I prefer to talk about what we can add to the diet to support normal hormone production and function. Here are the types of things that I discuss:

Best foods for PCOS

  • Low GI carbohydrates for slow energy release to maintain blood sugar control – e.g. porridge oats, wholegrain bread or pasta, brown rice.
  • Fruits and vegetables are a great way of getting more fibre. I tell my patients to make their plate as colourful as possible.
  • Lean protein e.g. fish, chicken, tofu, soybeans, lentils – protein is essential for hormone production and helps with blood sugar regulation.
  • Good quality fats e.g. nuts, avocado, salmon – fat is another essential building block for hormone production.

Foods to avoid with PCOS

Nothing is an absolute ‘no-go,’ but I do recommend trying to keep the following to a minimum:

  • Large amounts of high GI foods such as fruit juice, cakes, white bread and pasta, starchy vegetables e.g. potato without its skin.
  • Excess caffeine intake, this may disrupt sleep and can influence hormones.
  • Excess alcohol may also disturb sleep and is often full of sugar.
  • Prolonged periods of starvation which may increase the urge to binge.

What about dairy and gluten?

Many people ask about cutting out dairy. While some women report this improves their symptoms, there is a lack of research proving this hypothesis. While I don’t discourage women from trying, you do need to ensure you’re getting enough calcium, vitamin D and iodine from other sources, and I wouldn’t recommend continuing to cut out dairy if it doesn’t actually help. The same goes for gluten. There isn’t any evidence that a gluten-free diet will improve symptoms.

Women working out together

Six lifestyle changes to help with PCOS

1. Exercise

This is so important to build and maintain lean muscle, which helps to reduce insulin resistance. Exercise can also increase sex-hormone binding globulin (SHBG) levels, a hormone that is able to bind testosterone, making it less potent. There’s no best exercise for PCOS. I tell my patients the best exercise is the one that they enjoy and the one they’re going to stick to for the long-term. The only thing I would advise against is excessive amounts of high-intensity interval training. It’s great for 15-20 minute bursts a few times per week, but not long daily sessions, because that adds too much stress on your body and can also negatively impact your hormones.

2. Yoga

This can be a great way of combining exercise and mindfulness, and in fact, a study of 90 girls with PCOS in India showed that practising one hour a day for 12 weeks not only improved their menstrual cycle regularity, but also blood hormone profiles.

3. Stress

This can drive the adrenal glands to make more testosterone. Of course, we can’t remove stress entirely, but not all stress is psychological, and lack of sleep and extreme, excessive exercise are two common examples of stress that we can try and eliminate.

4. Sleep

Sleep hygiene is important to ensure adequate sleep quantity and quality, the lack of which can further disrupt hormone function.

5. Smoking

Have you ever met a doctor who didn’t tell you to stop smoking? Given the increased risk of heart disease with PCOS and from smoking – it’s a ‘no’ from me!

The bottom line…

PCOS is a long-term condition that can't be cured, but it’s important to discuss the sustainable lifestyle changes that may help your symptoms and look after your long-term health, rather than extreme, crash diets. Long-term follow-up of women with PCOS who maintained a healthy diet, exercised regularly and consumed alcohol in moderation had a 90 per cent lower risk of developing type 2 diabetes compared to those who didn’t, which is proof that making such lifestyle changes are worth the effort.

It’s important to point out that even with the best intentions, some people will not be able to manage their symptoms entirely in this way, and if that’s you, it’s not your fault. There are lots of medical treatments that we can also offer to manage symptoms, and it’s also helpful to ensure that you see a doctor to discuss these, and also to ensure that PCOS is in fact the correct diagnosis in your case.

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Dr Anita Mitra is an NHS doctor specialising in obstetrics and gynaecology who also appears online as 'The Gynae Geek', and has been described as "a trusted source of knowledge in an era of self-proclaimed gurus & internet-experts".


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