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What is Polycystic Ovary Syndrome and how can diet help to manage the symptoms?

PCOS dietitian surrey

What is Polycystic ovary syndrome?

Polycystic ovary syndrome (PCOS) is a very common condition, affecting approximately 1 in 10 women in the UK.

A diagnosis of PCOS is likely to be made in women who have 2 or more of the following:

1) The presence of fluid filled sacs known as follicles surrounding the eggs on the ovaries.

2) Irregular periods due to not ovulating (releasing eggs from the ovaries).

3) Higher levels of male hormones known as androgens (e.g., testosterone) which may cause physical signs such as excess facial hair.

What are the symptoms of PCOS?

If you have PCOS then you may experience some or all the below symptoms.

1) Irregular periods

2) Excess hair growth

3) Weight gain or difficult losing weight

4) Fatigue

5) Acne

6) Hair loss from head

Having PCOS can also increase your risk of developing type 2 diabetes and heart disease, particularly if you have high cholesterol, high blood pressure and/or carry excess fat around your middle.

Insulin resistance

Many of the side-effects associated with PCOS are because of insulin resistance. Insulin is a hormone that is released by the pancreas when we eat. Insulin allows the energy from our food to be used for fuel by moving the sugar from our blood into our muscles and tissues.

Most women with PCOS have a 35-40% decrease in insulin sensitivity which means that they must produce more insulin for it to do its job correctly. Unfortunately, insulin increases the production of the male hormone testosterone which causes a hormone imbalance and contributes to the above symptoms.

Weight loss

If you are overweight, then losing weight (even just 5-10%) is likely to help manage the symptoms of PCOS. Unfortunately, weight loss in PCOS can be more challenging for 2 reasons…

Firstly, research has consistently shown an association between insulin resistance and having a higher body fat percentage.

Secondly, women with PCOS are likely to have a lower basal metabolic rate (BMR, the number of calories burnt at rest). One study showed that BMR can be 14-40% lower compared with women who don’t have PCOS.

As we know, to lose weight we must be eating in a calorie deficit. Having PCOS means that to lose weight, fewer calories must be consumed, or more calories must be expended through exercise. Although the exact cause of this is not known, one study suggested that it may be due to lower lean body mass observed in PCOS.

Weight loss is not an easy thing alone, but when you add in the complications of PCOS, things get even harder. I can certainly empathise with women with PCOS who struggle with their weight. However, being armed with this information can help us to better understand how to tackle weight loss.

PCOS dietitian surrey

A healthy diet

The general guidelines for managing PCOS suggest following a healthy diet and this is certainly a good place to start.

Aim to have a varied diet, focusing on increasing your intake of fruits and vegetables and limiting your intake of foods high in fat and added sugar.

A Mediterranean style diet, high in omega 3 fatty acids, wholegrains and antioxidants has been suggested as one of the best diet types for managing PCOS.

Oxidative stress (antioxidant imbalance) has been associated with PCOS and therefore including plenty of antioxidant rich fruit and vegetables may be significant in symptom management.

If you are trying to conceive, it is especially important to make sure you are following a well-balanced diet.

As a starting point, try the following tips to help you improve the balance of your diet:

1) Base your meals on high fibre starchy carbohydrate

2) Eat a variety of different fruits and vegetables

3) Eat more fish, including one portion of oily fish per week

4) Cut down on saturated fat and added sugar

5) Eat less salt

6) Maintain a healthy weight

7) Aim for at least 6-8 glasses of fluid per day

8) Eat regular meal patterns

Low Glycaemic index

The term glycaemic index refers to how quickly your blood sugars increase after eating a particular food or meal. High GI foods cause our blood sugars to increase rapidly, whereas low GI foods do not (as illustrated below). The higher, our blood sugar levels, the more insulin we produce. As we know, PCOS is associated with insulin resistance which means that even more insulin is released and along with that comes the symptoms of PCOS.

By choosing low GI foods and limiting intake of high GI foods, insulin levels can be reduced and in turn symptoms are improved.

High GI carbohydrates include foods with added sugar and refined carbohydrate such as white bread.

Low GI carbohydrates include complex carbohydrates such as granary bread, boiled new potatoes, wholegrain cereals.

You can also help to lower the GI of a meal or snack by adding protein and fibre. Protein and fibre take a long time to be broken down into sugar so will help to prevent rapid increases in blood sugar levels.

PCOS dietitian surrey

Low carbohydrate diets

Many studies have shown that reducing carbohydrate intake can be a very effective method for improving insulin sensitivity, but carbohydrates, however, remain an important part of any diet. Carbohydrates are our primary energy source so without them we would likely feel low in energy and potentially quite hungry. They are also a rich source of fibre and micronutrients and usually quite an enjoyable component of the diet.

A low carbohydrate ketogenic (AKA keto) diet has been researched extensively and some research has linked it to reduced blood sugar levels and improved insulin resistance. This is however likely due to taking in fewer calories resulting in weight loss.

The standard version of a ketogenic diet recommends limiting your carbohydrate intake to 10% of your total energy and aims for 70% of total energy from fat.

One issue with the keto diet is that generally it is quite difficult to stick to due to the reasons mentioned above. It tends to work in the short-term but longer-term studies have shown reduced compliance and a tendency to regain any weight that was lost.

Another downside to the keto diet is that it is low in fibre, generally high in saturated fat and due to its restrictive nature may leave you lacking in some micronutrients. This is likely to increase the risk of certain cancers, heart disease and digestive issues. For these reasons, I would not recommend doing the keto diet long-term but for most people it would generally be considered safe to do in the short-term and may be a useful tool to help kick-start your weight loss journey. You should always consult with your dietitian or GP before considering a keto diet.

Reduced carbohydrate diets which allow for higher carbohydrate intakes than the keto diet have also been studied with some promising results.

A 2019 meta-analysis study involving 327 women with PCOS concluded that a reduced carbohydrate diet (45% of total energy or less from carbohydrate) combined with a reduced fat diet (35% of total energy or less from fat) was the most effective dietary method for improving insulin sensitivity and promoting weight loss.


Exercise improves insulin sensitivity because it encourages sugar to move from our blood and into our muscles to be used for energy. Research has shown that high intensity aerobic exercise is particularly beneficial.

Given that individuals with PCOS are likely to have lower BMR’s, if you are trying to lose weight it would also be sensible to include resistance training exercise as part of your routine. Resistance training exercise helps to build muscle and having a higher muscle mass means your BMR increases, making it easier to lose weight.

PCOS dietitian surrey


Vitamin D

Women with PCOS are at an increased risk of vitamin D deficiency. Vitamin D helps to reduce inflammation which is a contributing factor to the symptoms of PCOS. And although the mechanism is not fully understood, it has also been shown to improve regularity of periods.

Given that our main source of vitamin D comes from the sun and in the UK sunlight exposure is limited, I recommend taking a daily 10mcg vitamin D supplement. It may also be worth asking your GP to perform a blood test because if you are vitamin D deficient then you may need a higher dose initially to restore your levels to within the normal range.


Inositol is a sugar alcohol (type of carbohydrate) which plays an important role in insulin sensitivity. Many randomised control trials involving inositol supplementation in women with PCOS have shown positive outcomes such as improved fertility, reduced insulin resistance and decreased testosterone production.

Vitamin E

Vitamin E has been shown to have antioxidant effects. More recent evidence has also shown that vitamin E can improve endometrial thickness in women with unexplained fertility. One study showed that combined vitamin E and omega 3 supplementation for 12 weeks resulted in significant improvement in insulin resistance and reduced testosterone levels in women with PCOS.

Dietary sources of vitamin E include plant oils such as rapeseed or olive oil, nuts and seeds and wheat germ (found in cereals and cereal grains). If you are unlikely to consume these foods on a regular basis then you may want to consider a vitamin E supplement.


Some women with PCOS show reduced chromium levels which has been linked to insulin resistance and reduced testosterone. The recommended dosage is 200µg of chromium picolinate per day for 3 months to observe the benefits.


Women with PCOS who do not eat a varied diet are at increased risk of zinc deficiency which has been linked to insulin resistance and high cholesterol. Studies have shown improvements in both factors by taking 50mg of zinc sulphate daily for 8 weeks.

As a first line approach I would not recommend zinc supplementation, I would encourage you to try and get enough zinc through diet. Dietary sources of zinc include meat, beans, pulses, nuts, wholegrains, and milk.

N-acetyl-L-cysteine (NAC)

NAC has antioxidant activity and, in many studies, has been shown to reduce inflammation and oxidative stress and consequently improve fertility and ovulation rates for women with PCOS. In most studies, the suggested dosage is 600mg per day.


A 2019 study involving 80 women with PCOS found that supplementing 3g of L-carnitine daily for 3 months showed significant improvement in insulin sensitivity and reduced BMI. More regular menstrual cycles and reduced presence of facial hair also occurred.

Supplements, the bottom line

In the first instance, I tend to recommend addressing diet before considering the use of supplements. As a second line approach supplementation is another tool that may also help to relieve some of the symptoms of PCOS. If you want to try a supplement, then always consult with your GP or dietitian first. I would also always recommend trying one supplement at a time, otherwise you won’t know which one has or hasn’t worked for you.

PCOS dietitian surrey


BDA. 2019. Polycystic Ovary Syndrome (PCOS). Accessed 1st November 2021. Available at:

Bhasin, G., Wang, ET., Alexander, CJ., Pal, M., Azziz, R and Pisarska MD. 2013. Women with polycystic ovary syndrome (PCOS) have lower basal metabolic rates compared to eumenorrheic controls. Fertility and Sterility 100(3): 38-39.

Chmelik, M. 2015. N-acetyl-cysteine to treat polycystic ovarian syndrome? Natural medicine journal. 7(6). Accessed 1st November 2021. Available at:

Georgopoulos, NA., Saltamavros AD and Vervita, V. 2009. Basal metabolic rate is decreased in women with polyscystic ovary syndrome and biochemical hyperandrogenemia and is associated with insulin resistance. Fertility and Sterility 92(1): 250-255. Accessed 1st November 2021. Available at:

Gunalan, E., Aylin, Y and Yilmaz. 2018. The effect of nutrient supplementation in the management of polycystic ovary syndrome-associated metabolic dysfunctions: A critical review. J Turk Ger Gynecol Assoc. 19(4): 220-232. Accessed 1st November 2021. Available at:

Mavropoulos, JC., Yancy, W., Hepburn, J and Westman, EC. 2005. The effects of a low-carbohydrate, ketogenic diet on polycystic ovary syndrome: a pilot study. 2(35). Accessed 1st November 2021. Available at: 4

Mohammadi, M. 2019. Oxidative stress and polycystic ovary syndrome: a brief review. International Journal of Preventative Medicine. 10(86). Accessed 1st November 2021. Available at:

NHS. 2019. Polycystic Ovary Syndrome. Accessed 1st November 2021. Available at:

Paoli, A., Mancin L., Giacona, MC., Bianco., A and Caprio, M. 2020. Effects of a ketogenic diet in overweight women with polycystic ovary syndrome. Journal of translational medicine 18(104). Accessed 1st November 2021. Available at:

Salehpour, S., Nazari, L., Hoseini, S., Bameni, P and Gachkar, L. 2019. Effects of L-carnitine on polycystic ovary syndrome. JBRA Assist Repod 14;23(4): 392-395. Accessed 1st November 2021. Available at:

Thakker, D., Raval, A., Patel, I and Walia, R. 2015. N-acetylcysteine for polycystic ovary syndrome: a systematic review and meta-analysis of randomised controlled clinical trials. Obstet Gynecol Int 817849. Accessed 1st November 2021. Available at:

Zhang, X., Zheng, Y., Guo, Y and Lai, Z. 2019. The effect of low carbohydrate diet on polycystic ovary syndrome: a meta-analysis of randomized controlled trials. International journal of endocrinology. Accessed 1st November 2021. Available at:

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