Low carb diet for PCOS: fact or fad?

If you have taken to Google to research how to manage your PCOS symptoms we are sure you’ve seen advice to try a low-carb diet for PCOS management. But is there any evidence to support trying a low-carb diet for PCOS? Today, we’re diving deep into the role carbohydrates play in PCOS and the growing interest in low-carb diets as a potential way to manage symptoms. Let’s get started!

What is PCOS?

Polycystic ovary syndrome (PCOS), is a common endocrine condition. Signs and symptoms of the condition often become apparent during the late teenage years to early 20s but can affect anyone with ovaries of reproductive age.

All individuals with PCOS will encounter different symptoms ranging in severity, including irregular or no periods, difficulty getting pregnant, excess hair growth on the face and body (hirsutism), weight fluctuations, thinning hair on the head (alopecia), oily skin and/or acne.

What are carbohydrates?

Carbohydrates are one of the primary macronutrients found in our diet, which provide energy to our bodies. They can be simple, like sugars, or complex, such as starches and fibres. When consumed, most carbohydrates break down into glucose, raising blood sugar levels and causing the pancreas to release insulin.

Insulin is a hormone produced by the pancreas. It is involved in regulating blood glucose levels by facilitating the uptake of glucose into cells from the bloodstream.

What is a low-carb diet?

A low-carb diet restricts the intake of carbohydrates, typically emphasising more protein and fats. The aim of this diet, in theory, is to reduce insulin levels and encourage the body to burn stored fat for energy rather than use glucose for energy.

A ketogenic diet (keto) is an even stricter version of a low-carb diet, which restricts carbs to such an extent that the body enters a state called ketosis. In ketosis, the body primarily burns fat for energy instead of carbohydrates.

>> Read more | Ketogenic Diet and PCOS: Is Keto Good for PCOS?

What is the link between low-carb diet and PCOS?

Insulin resistance is a mechanism associated with PCOS and is often why a low-carb diet for PCOS is recommended. But what does it really mean? Insulin is a hormone that controls the amount of sugar in the blood. When an individual is insulin resistant it means that the body’s tissues are resistant to the effects of insulin. To compensate for this the body produces more insulin. Increased levels of insulin can exacerbate the symptoms of PCOS.

Insulin controls the amount of sugar in the blood by moving glucose from the blood into the cells to be converted into energy. Leading some to believe by reducing the amount of carbohydrates we consume; less insulin. It is hypothesised that this will then improve insulin resistance and symptoms of PCOS … but is there any science to back up this claim?

Does a low-carb diet work for PCOS?

Research suggests that low-carb diets may improve insulin resistance and other metabolic issues linked with PCOS. A small 2005 study found that a diet low in carbohydrates reduced testosterone levels and fasting insulin levels. But it is so important to mention that this study only had eleven people enrolled and only five actually completed the study!

Similarly, a 2020 study with fourteen people with PCOS found that a low-carb diet decreased glucose and insulin blood levels after twelve weeks. But it is important to note that the intervention was a ketogenic Mediterranean diet with phyoextracts – not just a low-carb diet! This study, again, was small and short-term, highlighting that more research is required.

When you look a little deeper into studies about low-carb diets for PCOS you find that the number of people in the studies is pretty small, and the drop-out rate is high. What should we take away from this? Firstly, we can’t conclude that low-carbohydrates benefit those with PCOS. Secondly, if a high percentage of people are dropping out of a study, it usually means that the diet is not sustainable and therefore would not be a long-term solution.

Cutting out carbohydrates or any whole food group from your diet is likely to contribute to disordered eating and eating disorders. Did you know that carbohydrates are our brain’s preferred energy source over any other? Cutting them out altogether firstly can be very challenging to do, but also can lead to adverse effects such as fatigue and also can leave you at risk of nutrient deficiencies.

Are there best carbs for PCOS?

It is important to note that there all foods fit if you have PCOS. Putting foods on pedestals may contribute to disordered eating behaviours. If you are looking for support on your food freedom journey check out our ultimate guide on Intuitive Eating for PCOS.

If you are looking for gentle nutrition tips to manage your PCOS symptoms then swapping to high-fibre, wholegrain carbohydrates may be helpful.

Increasing your fibre intake can be helpful for managing insulin resistance to slow the release of glucose into the blood. Wholegrain carbohydrates high in fibre may also be good for PCOS because fibre improves gut health, may lower inflammation and reduce levels of “bad” cholesterol.

3 swaps to higher fibre carbs

White rice to brown or wild rice: Brown and wild rice preserve their bran layer, which is removed from white rice during processing. This layer is rich in fibre.

Regular pasta for wholewheat pasta: Wholewheat pasta is made from the entire wheat kernel including the bran, germ and endosperm. Regular pasta has had the bran and germ removed.

White bread to wholegrain bread: Wholegrain bread uses the entire grain – increasing the amount of fibre present.

For more tips to boost your fibre intake, read our article on fibre for PCOS.

Alternative ways to manage PCOS symptoms

While diet plays a role, it’s just one part of the PCOS management puzzle. Regular exercise, stress management, certain medications and supplements may also be beneficial. Consulting with healthcare professionals can provide a personalised approach to PCOS. Check out our PCOS providers to find a trained pro to work with.

Key takeaways: low carb diet for PCOS

If you have PCOS then you may be looking for ways to eat to manage your symptoms. A low-carb diet is a popular diet for people with PCOS but the evidence about the efficacy of this diet is not robust enough. In fact, cutting out carbohydrates from your diet may lead to disordered eating behaviours or nutritional deficiencies. With any diet or lifestyle change, it is important to consult trained professionals for support.

Alex Okell ANutr Founder and Editor

Founder and Editor | Registered Associate Nutritionist


Founder of Be The Collective LTD [The PCOS Collective & The Endo Collective] Alex Okell ANutr is a London-based reproductive health nutritionist with experience in research, private practice and digital media. She holds a Master’s degree in Nutrition from King’s College London and has co-authored papers with the University of Cambridge, King’s College London, The Food Foundation and the Food Standards Agency. Alex offers 1:1 PCOS support in our virtual PCOS clinic.

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