Polycystic ovary syndrome (PCOS) is one of the most common hormonal conditions affecting women of reproductive age. It affects about one in 10 women. You would be hard pushed to pinpoint an area of the body that it doesn’t impact. It has endocrine, reproductive, cardiometabolic, dermatologic and psychological features.¹

Unfortunately, many women remain undiagnosed. Approximately 50% of women see three or more health professionals or wait longer than two years before receiving a PCOS diagnosis. Dietitians are in a prime position to screen women for risk and refer to their GP for assessment. Generally, the clinical assessment will be begin with a clinical history, signs of excess testosterone, discussions of menstrual history, and will be followed with bloods tests. If required, a women may be referred for an ultrasound of her ovaries. 

Diet and lifestyle changes offer one of the most powerful ways to manage PCOS effectively. Although medication may be required to help manage PCOS in some people, everyone with PCOS needs to consider diet and lifestyle modifications upon diagnosis. 

Most women (90%) are not happy with the information they receive about lifestyle management when they are diagnosed and nearly every woman wants more than the offer of medications to manage their condition. Please be aware that women of all shapes and sizes can be diagnosed with PCOS however issues with weight management has been reported as the most frustrating symptom.²

There is no ‘one-size-fits-all’ approach

Features of PCOS can have significant impacts on body image and quality of life. It’s important to be aware of this and thread softly. For example, there is an increased prevalence of disordered eating with PCOS so whatever dietary plan that is suggested needs to be mindful of this risk.³ Additionally, if you want to weigh the person you are advising, please ask permission first and consider when it might not be appropriate. 

The international evidence-based guidelines published in 2023 suggest that eating disorders and disordered eating should be considered in PCOS, regardless of weight, especially in the context of weight management and lifestyle interventions. My experience is that disordered eating and eating disorders are not suspected often enough and therefore those people are not referred to an appropriate qualified practitioner for further assessment. 

It is also worth noting that while in some cases PCOS can be better managed with body fat loss, the goal of weight loss can be harmful for others. Better PCOS management can be achieved in people with bigger bodies whether excess fat is lost or not. If the goal is reducing disease risk, then waist circumference and neck circumference measurements could be beneficial measures outside of total weight or total body fat percentage due to the associated diabetes and sleep apnoea risk.⁴

While there’s no ‘one-size-fits-all’ approach, the right dietary strategies can improve insulin sensitivity, regulate hormones, reduce inflammation and manage symptoms. 

Understanding insulin resistance in PCOS

One of the key players in PCOS is insulin resistance. Increased risks of insulin glucose tolerance and type 2 diabetes have been demonstrated on meta-analyses, independent of BMI.⁵ When the body becomes resistant to insulin, the pancreas pumps out more, leading to higher insulin levels. This not only makes weight management more challenging but also increases testosterone production, which contributes to symptoms like excess hair growth on the body, acne, and hair loss on the scalp.

Insulin resistance resulting in compensatory hyperinsulinemia affects 65-70% of women with PCOS. However, estimates suggest one in five women with PCOS with a BMI of >30kg/m² are impacted and one in four women with a BMI <25.⁶

When insulin resistance is involved, the goal is to use diet and lifestyle medication to manage it. And that’s where a Mediterranean-style, low glycaemic index (GI) diet comes in.

Mediterranean diet approach/DASH diet

A Mediterranean-style diet and the dietary approaches to stop hypertension (DASH) diet are best researched dietary patterns for managing PCOS. These two dietary patterns are very similar, focusing on:

• Low-GI carbohydrates: Swap refined carbs for whole grains varieties, eg. rye, wheat, oats, rice. Not only will this offer more fibre but also the nutrient-packed germ layer. Wholegrains can contain up to 75% more nutrients than refined cereals such as essential fatty acids, B vitamins, antioxidants, and phytochemicals.⁷ This can help with hunger hormones, waist circumference, BMI, insulin sensitivity, reproductive hormones and cardiometabolic disease risk⁸
• Healthy fats: Extra virgin olive oil, avocado, nuts, and seeds provide essential fats, antioxidants and micronutrients. With many women with PCOS there can be a reluctance to including healthy fats in their diet due to worries about calorie intake 
• Fruit and vegetables: Fruit and vegetables are the foundation of both dietary patterns with aims of reaching above five portions as standard
• Lean proteins: Within the research, there is a trend showing higher protein diets are helpful in PCOS for helping manage body size (BMI, waist circumference, total weight, waist hip ratio, fat mass), insulin levels, cholesterol levels, triglycerides and hirsutism.⁹ Keeping in line with these dietary patterns, the goal for many is to introduce more fish and legumes.

Role of supplements 

While diet is the foundation, supplements can help fill nutrient gaps and target specific PCOS-related concerns. Here’s what to consider:

Nutrient support

• Vitamin D: Deficiency is common in women with PCOS and is linked to poor insulin sensitivity and irregular cycles,^10,11 Supplementing may be beneficial and is nearly always required
• Omega-3 Fatty Acids: Omega 3 supplements have been found to be beneficial for metabolic parameters in PCOS.¹² Supplementing with 1-3g of fish oil daily can be useful
• Vitamin B12: A supplement of vitamin B12 is often required for those taking metformin, especially in those taking a higher dose or on it long term. Generally, when vitamin B12 deficiency is being managed, people start to improve within two weeks but can take up to three months¹³
• Myo-inositol: Inositol, particularly a combination of myo-inositol and d-chiro inositol has been shown to help with menstrual regularity, BMI, androgen levels and blood sugar levels.¹⁴ The recommended dose is around 2,000-4,000 mg daily.

Therapeutic foods for PCOS

Certain foods have been shown to offer additional benefits for women with PCOS beyond their macronutrient composition. These include:

• Cinnamon: While technically a spice, cinnamon has been shown to help manage insulin resistance, cholesterol levels and inflammation.¹⁵ Adding a half to one teaspoon to meals daily may help
• Walnuts and almonds: Provide healthy fats, micronutrients, plant compounds and fibre, these nuts have been shown to help with cholesterols, blood glucose management as well as insulin and hormone (SHBG, free androgen index) levels¹⁶
• Flaxseeds: 30g grams a day of flaxseed, a seed providing omega 3 fats, soluble fibre and phyto-oestrogens, was shown to reduce body weight, insulin, cholesterol and leptin levels.¹⁷

Lifestyle factors beyond the plate

Diet is a critical piece of the PCOS puzzle, but lifestyle habits also play a major role.

Exercise 

Physical activity can have positive health benefits. Although there is talk of specific exercise types for PCOS on social media, the research isn’t there yet. Realistically, sustainable physical activity based on individual preferences and goals should be encouraged. 

Recommendations for maintenance of health

• Adults should aim for a minimum of 150 to 300 minutes of moderate-intensity activities or 75-150 minutes of vigorous-intensity aerobic activity per week 
• Plus muscle strengthening activities, eg. resistance/flexibility on two non-consecutive days per week. 

Prioritising sleep 

Sleep effects every facet of life. Women with PCOS have significantly higher prevalence of obstructive sleep apnoea, independent of BMI. A dietitian is in prime position to help screen for sleep apnoea by asking simple questions like 

• Do you snore?
• Do you wake feeling unrefreshed from sleep? 
• Do you have daytime sleepiness or fatigue?

The person can be screened further with validated tools or refer for assessment with their GP. 

Putting it all together

There’s no magic bullet for PCOS, but a Mediterranean-style, low-GI diet, slightly higher protein intake, targeted supplements, and lifestyle changes can go a long way in managing symptoms. The key is consistency and personalisation – what works for one woman might not work for another. Support is crucial as well as aiming to gain a better understanding of environmental and systems drivers of behaviour.

As dietitians, we have the opportunity to empower women with PCOS by helping them build a sustainable approach to nutrition and lifestyle that supports long-term health. By focusing on holistic wellbeing, we can make a significant difference in their quality of life, and perhaps quantity of life too. 

1. International evidence-based guideline for the assessment and management of polycystic ovary syndrome 2018. Monash University. Available from: https://www.monash.edu/medicine/mchri/pcos/guideline
2. Gibson-Helm M , Teede H , Dunaif A. J Clin Endocrinol Metab.2017;102 (2): 375-378
3. Chaudhari AP et al. Anxiety, Depression, and Quality of Life in Women with Polycystic Ovarian Syndrome. Indian J Psychol Med. 2018 May-Jun;40(3):239-246
4. Insert reference for sleep apea diabetes risk and waist plus neck circumference
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6. DeUgarte CM, Barolucci AA, Azziz R. Prevalence of insulin resistance in the polycystic ovary syndrome using the homeostasis model assessment. Fertil Steril. 2005;83:1454–1460. doi: 10.1016/j.fertnstert.2004.11.070
7. https://www.bda.uk.com/resource/wholegrains.html
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13. https://www.nice.org.uk/guidance/ng239/chapter/recommendations#managing-vitamin-b12-deficiency
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