Polycystic ovary syndrome (PCOS) is an endocrine condition that affects your ovaries. Some people with PCOS might find they easily put on weight, as well as find it really difficult to lose excess weight. This is often a result of insulin resistance — when you don't respond to insulin properly. There are a number of lifestyle changes that can reduce insulin resistance and help you lose weight.

Medically reviewed by Dr Rebecca Kingston MBChB, Medicine

What is PCOS?

PCOS is a common endocrine disorder that affects your ovaries — it's estimated to affect as much as 1 out of 5 women. Your endocrine system is responsible for producing various hormones in your body.

There are 3 main features of PCOS, but you only need to have 2 out of 3 to be diagnosed with PCOS:

  • irregular or missing periods — due to irregular or absent ovulation
  • high levels of "male" hormones — a blood test will usually measure your testosterone levels
  • polycystic ovaries — where your ovaries are enlarged and contain fluid-filled sacs 

What are the signs of PCOS? 

Common signs of PCOS include:

  • irregular or missing periods 
  • excessive hair growth — especially on the back, face, or chest
  • difficulty getting pregnant 
  • oily skin and acne 
  • weight gain

How does PCOS affect your weight?

It’s not clear whether PCOS is a direct cause of weight gain. But there’s a clear link between PCOS and high levels of the hormone insulin — which can cause weight gain. This can then lead to insulin resistance (when your cells don’t respond properly to insulin).

What is insulin?

Insulin is a hormone produced by your pancreas. Its main function is to control the level of sugar (glucose) in your blood.

When you eat, your blood sugar levels rise and your pancreas releases insulin. Insulin then stimulates your cells to take up sugar from your blood — which they use for energy.

If your cells are less sensitive to the effects of insulin it’s called insulin resistance. This essentially means that your cells don’t respond to insulin properly and the sugar in your blood has trouble moving into your cells.

Insulin resistance and PCOS 

PCOS causes a range of hormones in your body to become imbalanced, sometimes this includes causing high levels of insulin.

If your cells don’t respond to insulin, your body produces even more insulin to help regulate your blood glucose — this increases inflammation and fat storage, as your liver converts any excess glucose into fat. 

High levels of insulin also cause your ovaries to produce too much testosterone. This can lead to weight gain — especially around your stomach and upper body. It can also interfere with ovulation and fertility.

Between 50-70% of women with PCOS are insulin resistant

Long-term risks of insulin resistance

PCOS-related insulin resistance and weight gain can increase your risk for the following conditions:

  • prediabetes — blood sugar levels are higher than normal, but not high enough to be classified as type 2 diabetes
  • type 2 diabetes
  • high blood pressure
  • heart disease — particularly if you carry excess weight on your stomach

How to manage your weight with PCOS

Losing weight with PCOS can be more difficult. But there are a number of lifestyle changes that can reduce insulin resistance and help you lose weight. And even a very small amount of weight loss can significantly improve your symptoms. Weight loss might also:

  • reduce your risk of type 2 diabetes and cardiovascular disease
  • regulate your periods
  • improve fertility — if you're struggling to get pregnant

Eat a high protein, low GI diet

Aim for 30% of your calorie intake to be from high-protein foods. And opt for low glycaemic (low GI) foods — this means getting carbohydrates from low GI foods like fruits, vegetables, and whole grains. 

This diet style can help to reduce androgen levels, like testosterone, and improve insulin resistance. If you have PCOS and don’t carry excess weight, this can still be beneficial for you.

Some early research also suggests that flaxseed supplementation and making sure you’re getting enough vitamin D and calcium might also help reduce symptoms.

Do some high-intensity and resistance training

Exercise is one of the most effective ways to improve your insulin response. In particular, high-intensity interval training and resistance (strength) training seem to be very beneficial if you have PCOS.

Try an inositol supplement

Inositol is a vitamin-like substance that helps regulate your insulin response. Early research shows some promising results with these forms of inositol supplementation:

  • myo-inositol — might improve metabolic and reproductive health 
  • d-chiro-inositol — might help to reduce androgen levels, like testosterone

So far research suggests taking a 40:1 ratio of myo-inositol to d-chiro-inositol. It’s a good idea to speak with your doctor, pharmacist, or a dietitian if starting a supplement. 

Medication

Your doctor can prescribe medication or oral contraception to help you regulate your hormones.

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References

Almenning, I., Rieber-Mohn, A., Lundgren, K. M., Løvvik, T. S., Garnæs, K. K., & Moholdt, T. (2015). Effects of high intensity interval training and strength training on metabolic, cardiovascular and hormonal outcomes in women with polycystic ovary syndrome: a pilot study. PLoS One, 10(9), e0138793.

Glenville, M. (2012). Natural Solutions to PCOS: How to Eliminate Your Symptoms and Boost Your Fertility. Pan Macmillan.

Hardy, O. T., Czech, M. P., & Corvera, S. (2012). What causes the insulin resistance underlying obesity?. Current opinion in endocrinology, diabetes, and obesity, 19(2), 81.

Kadoura, S., Alhalabi, M., & Nattouf, A. H. (2019). Effect of calcium and vitamin D supplements as an adjuvant therapy to metformin on menstrual cycle abnormalities, hormonal profile, and IGF-1 system in polycystic ovary syndrome patients: a randomized, placebo-controlled clinical trial. Advances in pharmacological sciences, 2019.

Marshall, J. C., & Dunaif, A. (2012). Аll women with PCOS should be treated for insulin resistance. Fertil Steril, 97(1), 18-22.

Thys-Jacobs, S., Donovan, D., Papadopoulos, A., Sarrel, P., & Bilezikian, J. P. (1999). Vitamin D and calcium dysregulation in the polycystic ovarian syndrome. Steroids, 64(6), 430-435.

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