The PCOS diet: What does the science say?

Many of us have heard of PCOS, but it’s often misunderstood. You might have read about it and that diet is important, but it can be hard to unpick how exactly it all works, and what on earth it has to do with food. 


First, we have to start with the basics.

What is PCOS? 

Polycystic ovary syndrome, or ‘PCOS’, is a condition caused by small cysts growing on a person's ovaries, which cause hormonal imbalances. It’s one of the most common hormonal disorders in women of childbearing age, affecting around one in 10.

The World Health Organisation (WHO) estimates up to 70% of women with PCOS across the world, remain undiagnosed. Pretty unbelievable!

Diet may be a key piece of the puzzle of several aspects of PCOS, for example:

  • hormone imbalances
  • heavy, irregular or absent periods 
  • food cravings 
  • high blood sugars or ‘insulin resistance’ 
  • weight that won’t shift, no matter what you eat 
  • hair loss or excess hair where you don’t want it 
  • skin problems and acne 
  • fertility problems 

Working with a dietitian can teach you all about: 

  • How to eat to support healthy hormone balance.
  • Supplements - what they’re for and which may be right for you.
  • If weight loss is a goal, you can learn ways to understand your individual metabolism and how to work with, not against, your body.
  • Tools to incorporate what you have learned into practical, sustainable changes. 

Excess weight

Not everyone with PCOS will have trouble with weight gain (more on lean PCOS another day), but for some women, the hormonal imbalances that come along with PCOS can make maintaining a healthy weight really difficult. For example, too much testosterone encourages your body to store fat around the middle.

It’s a bit of a tricky cycle because excess weight can then fuel hormones, leaving too many of us not knowing what else to try! 

Nutrition can play a big role in helping to break this cycle, supporting your body to process sugars and balance hormones in a healthy way. 

High blood sugars 

Insulin is one of the most important hormones when it comes to regulating our blood sugars and helping us to process energy correctly. Sometimes as part of PCOS, your body doesn’t respond as well, or becomes 'resistant' to insulin. It then makes extra to compensate. Extra insulin can lead to us storing more body fat. 

High levels of Insulin also increase testosterone levels, which contributes to lots of difficult symptoms like acne, and excess hair growth.

Regulating your insulin is also an important part of looking after your long-term health.

Dysregulated hormones

Women with PCOS often have high levels of testosterone, oestrogen and two less commonly known hormones called luteinising hormone (LH) and anti-müllerian hormone (which measures the fertility level of the ovaries).

Diet changes tailored to your hormonal profile can help to regulate these, as well as increasing a helpful hormone called Sex Hormone Bonding Globulin or SHBG. 

Chronic inflammation

Women with PCOS have been shown to have higher levels of inflammatory molecules called AEGs, which can cause damage to cells and can collect in the ovaries. 

The good news is that diet changes such as reducing foods high in AEGs, improving your gut health and including antioxidant-rich foods can significantly reduce the number of AEGs in your body. 

Long term health 

Looking after your long-term health with PCOS is really important, like working on improving your insulin sensitivity. Mental health is also really important so linking in with the right support and feeling empowered to make changes makes a big difference. 


The world of supplements can be bewildering. There are so many options out there but it’s important to know which ones are right for you and if they actually have scientific backing.

Everyone’s needs can be very different here, so it’s really important to work with your healthcare team. 

Science suggests that the right supplements may help to regulate your period and ovulation, improve excess hair, your insulin sensitivity, and regulate testosterone. They may also help with high cholesterol and a specific few may be needed if you want to improve your fertility. 

Working with a registered dietitian (RD) 

It’s important we remember that PCOS is a medical condition which looks very different for different people. It’s important that the help and information you are accessing is scientific, safe and tailored to your test results and medical history. 

How medical nutrition therapy can help

A hormonal specialist registered dietitian is able to diagnose and treat nutritional problems and take you through the process of nutrition therapy, getting you set up with all the practical tools you need to make achievable, sustainable changes. 

Where should I go from here?

If you have been diagnosed with PCOS, it can feel so overwhelming.

If you’re not sure where to go, or you would like a nudge in the right direction to find the right help for you, get in touch via email or book a free discovery call.  

My biggest message - you are not alone!

Remember, the info in this article is for general information only. Everyone with a health condition is different, so always speak with your healthcare team before making any big changes. 

The views expressed in this article are those of the author. All articles published on Nutritionist Resource are reviewed by our editorial team.

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London WC2H & W1H
Written by Emily Reilly, RD, MNutr
London WC2H & W1H

Hi, I’m Emily! As an experienced Registered Dietitian, I’m passionate about the life-changing power of nutrition. I work with my clients to translate cutting-edge nutritional research into inspiring nutrition coaching.

Our lives are so busy! So my approach is to make advice and recipes which are actually do-able, and tailored to you.

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