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PCOS, nutrition and fertility

22 September 2020

Polycystic ovary syndrome or PCOS is the most common hormonal condition in women of reproductive age, with 1 in 10 women in the UK estimated to be affected. The signs of PCOS include irregular periods, excess androgen (testosterone) levels and enlarged ovaries that contain fluid filled sacs surrounding the eggs. Having two or more of these features may lead to PCOS diagnosis (1).

The cause is unknown however, the majority of people with PCOS show resistance to the hormone insulin, the role of which is to regulate blood sugar levels. To compensate, more insulin is produced contributing to the increased production of androgens which have an important role in regulating female fertility (2). Alongside difficulties in getting pregnant due to irregular ovulation or failure to ovulate, having PCOS can also lead to excessive unwanted hair growth, weight gain, thinning hair and/or hair loss and oily skin or acne.

The average BMI of people with PCOS is generally higher than those without the condition. Being both insulin resistant and of a higher weight can lead to a state of low grade inflammation (3), increasing risk of infertility, the risk of developing metabolic problems in later life such as Type 2 diabetes and cardiovascular disease as well pregnancy complications such as gestational diabetes and preeclampsia.

There is currently no cure for PCOS, however the good news is the symptoms can be treated, with diet playing a major role. So is there a ‘PCOS diet’? Thankfully, there are changes you can make to promote weight management, help regulate insulin levels, balance reproductive hormones, regulate menstrual cycles and promote fertility. Let’s take a look at what changes can be made.

PCOS and weight loss

A loss of 5% body weight has been shown to improve these outcomes (4). If you want to know what a 5% weight loss would be for you, take your weight in kg and multiply by 0.05 - this will tell you the amount of weight loss to aim for as a first step.

PCOS and carbohydrates

Due to its direct effects on blood glucose and insulin, lowering dietary carbohydrate intake can improve hormonal balance, promote normal ovulation and improve pregnancy rates (5). Furthermore, women affected by PCOS can find it easier to lose weight by reducing their total carbohydrate intake. We find carbohydrates in bread, rice, pasta, cereals and other grains, remembering that sugar is also a form of carbohydrate. We don’t want to cut out carbohydrates completely but a reduction could be advantageous, and try to keep added sugars (cakes, biscuits, sweets etc.) to a minimum.

PCOS and a low glycaemic index (GI) diet

In PCOS, thinking about type of carbohydrate is just as important as the amount. Lower glycaemic index options, such as fruit, vegetables, wholegrains, oats, chickpeas and lentils, release energy more slowly and do not affect blood glucose levels to as great an extent as refined carbohydrates such as white bread, white rice and white pasta, and sweet desserts. Switching to lower glycaemic index options can improve insulin sensitivity and menstrual irregularities, reduce inflammation and promote weight loss (6).

Keto diet for PCOS?

Some research suggests that a ketogenic diet could be beneficial in PCOS for reducing weight, blood glucose and insulin levels, blood lipids and testosterone (7) in the short term. It is important however to bear in mind that sustaining the very low levels of carbohydrate intake required for a ketogenic diet is extremely difficult, impairing the long term benefits. Additionally its restrictive nature increases risk of deficiencies in B vitamins and calcium, fibre intake is also severely reduced which itself has been shown to promote improvements in regulating blood sugar (8,9). A balanced approach to carbohydrate intake is recommended with intakes in the range of 100-200g of carbohydrate per day. This allows inclusion of fibre, and a wide variety of fruits and vegetables, providing powerful antioxidants such as vitamins C and E, both of which can combat inflammation (10) and are extremely important for fertility.

PCOS and the Mediterranean diet

A Mediterranean style diet incorporates these anti-inflammatory aspects along with a moderate intake of low glycaemic index carbohydrates (11). Choosing healthy sources of fat such as omega-3 fatty acids in the form of oily fish or as a supplement and reducing intakes of saturated fat also contribute to reducing inflammation (12,13).

PCOS and protein

Alongside being an essential dietary component for growth, repair and maintenance, protein can help stabilise blood sugar, control appetite and keep you feeling full. Incorporating higher amounts of protein in the diet can improve weight loss and glucose metabolism in women with PCOS (14). Moderate increases up to 30% of energy intake per day are recommended as consuming too much could have the opposite detrimental effect. Consideration of the protein source is recommended as excess protein intake from animal sources, such as red meat, could further promote insulin resistance and inflammation.

Supplements for PCOS

As well as these dietary changes there is encouraging data to suggest supplementation with myo-inositol, a vitamin like, naturally occurring substance, produced from carbohydrate, could be effective in improving ovarian function, metabolic profile and hyperandrogenism women with PCOS (15,16). A comprehensive review of the topic found that myo-inositol alone, or in combination with D-chiro-inositol, was capable of restoring spontaneous ovulation and improving fertility in women with PCOS (17), so it is a supplement that could be considered in those affected by PCOS.


PCOS can be a challenging condition to manage, but understanding the dietary principles discussed above and incorporating these elements has the potential to help manage symptoms, promote overall health, promote fertility and increase chances of getting pregnant with PCOS.


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