PCOS and Nutrition: What Actually Works (From a Dietitian)

Polycystic ovary syndrome (PCOS) affects around 1 in 10 women in the UK, yet nutrition advice online is often contradictory, overwhelming, or just plain wrong. As a registered dietitian who works with many clients with PCOS, I want to cut through the noise and share what the evidence actually says and what genuinely helps.

Diverse women posing

Why diet matters in PCOS

PCOS is a hormonal condition, but it's closely linked to insulin resistance in around 70% of cases. Insulin resistance means your body produces more insulin than it should and elevated insulin levels worsen the hormonal imbalances that drive PCOS symptoms like irregular periods, excess androgens, acne, and difficulty managing weight.

What the evidence supports

A lower glycaemic load diet - one that moderates blood sugar spikes - is consistently associated with improvements in insulin sensitivity, androgen levels, and menstrual regularity in women with PCOS. This doesn't mean cutting out carbohydrates entirely. It means choosing carbohydrates that release glucose more slowly: wholegrains, legumes, oats, and plenty of vegetables.

Anti-inflammatory eating patterns, such as the Mediterranean diet, are also well supported. PCOS involves chronic low-grade inflammation, and dietary patterns rich in olive oil, oily fish, nuts, seeds, legumes, fruits and vegetables have been shown to reduce inflammatory markers and improve metabolic health in PCOS.

Adequate protein at each meal helps with blood sugar regulation and satiety. Aim for a source of protein at breakfast, lunch and dinner — eggs, Greek yoghurt, pulses, fish, chicken or tofu all work well.

What doesn't help

Very low calorie diets and extreme restriction often backfire in PCOS. They can increase cortisol levels, disrupt the hypothalamic-pituitary axis, and worsen hormonal balance. Crash dieting tends to increase insulin resistance over time and can make cycles even more irregular.

Cutting out entire food groups - dairy, gluten, all carbohydrates — is not supported by strong evidence for PCOS unless there's a specific diagnosed intolerance. These restrictions make eating more stressful without meaningful benefit.

Supplements worth knowing about

Inositol (particularly myo-inositol) has good evidence for improving insulin sensitivity, menstrual regularity and egg quality in PCOS. Vitamin D deficiency is very common in women with PCOS and worth testing for. Omega-3 fatty acids have anti-inflammatory effects that may benefit PCOS symptoms. Always discuss supplementation with a healthcare professional before starting.

Ready for personalised support?

PCOS responds really well to the right dietary changes — but a generic plan rarely cuts it. If you'd like personalised support tailored to your symptoms, your lifestyle, and your goals, I offer a free 15-minute discovery call. No obligation, just a conversation about how I can help.