There are so many diets touted as “the best diet for PCOS” by gurus across the internet. But one way of eating comes up again and again – the low glycemic diet for PCOS. But what exactly is the glycemic index and does this way of eating help improve PCOS symptoms? Keep reading to learn more.
What is PCOS?
Polycystic ovarian syndrome (PCOS) is a common endocrine (hormone) disorder that affects approximately 8-13% of people assigned female at birth worldwide. It is often characterised by irregular or a lack of periods, and high androgen levels leading to symptoms like hirsutism, alopecia, oily skin and acne, as well as polycystic ovaries.
What is a low glycemic diet?
A low glycemic diet is a way of eating where you prioritise consuming foods that are low on the glycemic index. The glycemic index (GI) is a scale of 1-100 that measures how quickly and how much your blood sugar levels rise following the consumption of carbohydrates.
Imagine that your blood sugar is like a roller coaster. Foods with a high glycemic index are the steep rises and fast drops on a roller coaster. They cause a quick burst of energy followed by a crash. Foods with a low glycemic index are the meandering, rolling hills of a roller coaster. They provide a slow, steady release of energy. Slowly absorbed carbohydrates have a low GI rating of 55 or below.
Eating a low glycemic diet involves choosing foods that are low on the glycemic index such as whole grains, legumes and non-starchy vegetables whilst avoiding foods that are high on the index such as chocolate bars, sweets and fizzy drinks.
What is the link between PCOS and a low GI diet?
A low glycemic diet and PCOS have been linked primarily because of the role insulin resistance plays in PCOS. Insulin resistance is both a driver and a symptom of PCOS. There are several signs that may indicate insulin resistance in people with PCOS including Acanthosis Nigricans, skin tags, carbohydrate cravings, fatigue, increased thirst and tingly hands and feet.
Insulin resistance is when the body’s tissues are resistant to the effect of insulin. This means when glucose enters the bloodstream after eating, the glucose cannot enter the cells as we would expect. This means that blood glucose, also known as blood sugar, levels are high in people with insulin resistance.
Low glycemic index foods may be helpful for people with insulin resistance as they are digested more slowly than high GI foods. This slow digestion results in a gradual rise in blood sugar levels, consequently improving the reaction to insulin levels in the body and preventing a sudden rise in insulin. Therefore, consuming low GI foods may help to improve insulin resistance; a prominent symptom of PCOS.
This is important because raised insulin levels also give rise to increased testosterone levels. Hyperandrogenism in people with PCOS can result in acne, irregular periods, and excess hair. This highlights how managing insulin resistance can improve other symptoms of PCOS, like those related to hyperandrogenism.
Pros and cons of a low glycemic diet for PCOS
As with any way of eating, there are pros and cons of a low GI diet. Potential pros of a low GI diet for PCOS include improved insulin levels, reduced body hair, improved period cyclicity and more stable energy and mood. Cons of a low GI diet include an emphasis solely on GI without taking nutrient balance into account, the variability in GI values and the challenge of adhering to the diet.
Pros of a low GI diet
Two-hour insulin levels and HOMA-IR (a model to assess the relationship between glucose and insulin) were significantly lowered in people with PCOS consuming a low glycemic diet in a study. However, this meta-analysis did not find any statistically significant differences in fasting glucose, fasting insulin, two-hour glucose and HbA1c between the low GI diet and the control diet. This highlights the need for more research on the low GI diet in people with PCOS.
As raised insulin is linked to raised androgen levels, a low GI diet has been seen to reduce symptoms of hyperandrogenism such as body hair in some studies. A 2021 systematic review and meta-analysis found that a low GI diet significantly lowered body hair in people with PCOS compared to those on a control diet.
The low GI diet appears to improve period cyclicity in people with PCOS, especially those who are also taking metformin – a common insulin sensitiser. It is important to mention that this was a small study of 96 people and only 49% of people actually completed the trial, highlighting the challenge of sticking to a restrictive way of eating.
A low glycemic diet has been linked to stable energy levels because of its ability to stabilise blood sugar levels. Plus, a low GI diet has been associated with fewer depression symptoms, reduced fatigue and lower mood disturbances. People with PCOS are at a higher risk of depression and fatigue compared to the general population so a low GI diet may help to manage these symptoms. However, we need more research specifically on people with PCOS and the low GI diet in relation to energy, mood and fatigue to understand the connection.
Cons of a low GI diet
A con of a low glycemic diet is the emphasis solely on GI. The glycemic index is just one way to classify foods. It doesn’t take into account the overall nutrient balance of a food. For example, red meat has a lower GI index than mango but we know that eating too much red meat can be damaging to our health long-term. Also, the GI doesn’t consider the quantity of carbohydrates consumed, which is essential to understanding the effect of food on blood sugar levels.
Interestingly, the variability in GI values can be huge. This is because the GI of a food can vary based on how it is prepared, how ripe it is and its variety. This can make it difficult to calculate the exact GI value of a food.
As with any diet or restrictive way of eating, the low glycemic diet may be challenging to adhere to long-term. Plus, strictly following a low GI diet could lead to disordered eating behaviours and even eating disorders, and we know that people with PCOS are at a higher risk of developing eating disorders than the general population.
Having strict and rigid rules surrounding food and movement can actually be more damaging to people with PCOS which is why we recommend intuitive eating for PCOS at The PCOS Collective.
99 low GI foods for PCOS
If you choose to follow a low glycemic diet to help improve your PCOS symptoms, then you will need to have a list of low GI foods to incorporate into your diet. We’ve rounded up 99 low-GI foods (food with less than a score of 55 on the glycemic index) here.
- Barley – GI: 28 | Sugar: 0.8g
- Cherries – GI: 22 | Sugar: 8g
- Grapefruit – GI: 25 | Sugar: 7g
- Lentils – GI: 32 | Sugar: 1.8g
- Whole Milk – GI: 27 | Sugar: 5.1g
- Kidney Beans – GI: 29 | Sugar: 0.2g
- Pears – GI: 38 | Sugar: 10g
- Apples – GI: 36 | Sugar: 10g
- Plums – GI: 40 | Sugar: 10g
- Oranges – GI: 43 | Sugar: 8.2g
- Carrots – GI: 39 | Sugar: 4.7g
- Chickpeas – GI: 33 | Sugar: 0.6g
- Peanuts – GI: 14 | Sugar: 4.7g
- Yoghurt (without added sugar) – GI: 35 | Sugar: 5g
- Soy Beans – GI: 18 | Sugar: 3g
- Tomatoes – GI: 15 | Sugar: 2.6g
- Walnuts – GI: 15 | Sugar: 2.6g
- Cashews – GI: 22 | Sugar: 5.9g
- Black Beans – GI: 30 | Sugar: 0.3g
- Navy Beans – GI: 31 | Sugar: 0.2g
- Green Peas – GI: 48 | Sugar: 5.7g
- Broccoli – GI: 15 | Sugar: 1.7g
- Mushrooms – GI: 10 | Sugar: 1.7g
- Cabbage – GI: 10 | Sugar: 3.2g
- Lettuce – GI: 10 | Sugar: 0.8g
- Eggplant – GI: 15 | Sugar: 3.5g
- Peaches – GI: 42 | Sugar: 8.4g
- Strawberries – GI: 41 | Sugar: 4.9g
- Quinoa – GI: 53 | Sugar: 0.9g
- Bulgur – GI: 46 | Sugar: 0.4g
- Brussels Sprouts – GI: 15 | Sugar: 2.2g
- Cauliflower – GI: 15 | Sugar: 1.9g
- Artichokes – GI: 15 | Sugar: 1.4g
- Onions – GI: 10 | Sugar: 4.7g
- Pumpkin Seeds – GI: 10 | Sugar: 1.3g
- Almonds – GI: 15 | Sugar: 3.9g
- Hazelnuts – GI: 15 | Sugar: 4.3g
- Sunflower Seeds – GI: 20 | Sugar: 2.6g
- Green Beans – GI: 15 | Sugar: 3.3g
- Spinach – GI: 15 | Sugar: 0.4g
- Cucumbers – GI: 15 | Sugar: 1.7g
- Zucchini – GI: 15 | Sugar: 2.5g
- Olives – GI: 15 | Sugar: 0g
- Sesame Seeds – GI: 35 | Sugar: 0.3g
- Tofu – GI: 15 | Sugar: 0.7g
- Fennel – GI: 15 | Sugar: 3.9g
- Bok Choy – GI: 15 | Sugar: 1.2g
- Swiss Chard – GI: 15 | Sugar: 1.1g
- Kale – GI: 15 | Sugar: 0.9g
- Mustard Greens – GI: 15 | Sugar: 0.8g
- Turnip – GI: 37 | Sugar: 3.8g
- Raspberries – GI: 32 | Sugar: 4.4g
- Blackberries – GI: 25 | Sugar: 4.9g
- Flaxseeds – GI: 35 | Sugar: 1.5g
- Asparagus – GI: 15 | Sugar: 2.2g
- Leeks – GI: 15 | Sugar: 3.9g
- Collard Greens – GI: 15 | Sugar: 0.5g
- Parsley – GI: 15 | Sugar: 0.9g
- Bell Peppers – GI: 15 | Sugar: 4.2g
- Oysters – GI: 15 | Sugar: 0.9g
- Watercress – GI: 15 | Sugar: 0.2g
- Okra – GI: 20 | Sugar: 0.3g
- Radishes – GI: 15 | Sugar: 1.9g
- Celery – GI: 15 | Sugar: 1.3g
- Garlic – GI: 30 | Sugar: 1g
- Ginger – GI: 15 | Sugar: 1.7g
- Avocado – GI: 15 | Sugar: 0.7g
- Lime – GI: 25 | Sugar: 1.1g
- Lemon – GI: 20 | Sugar: 2.5g
- Guava – GI: 12 | Sugar: 5.4g
- Apricots – GI: 34 | Sugar: 3.9g
- Mung Beans – GI: 54 | Sugar: 2g
- Pasta (whole wheat) – GI: 37 | Sugar: 0.8g
- Couscous (whole wheat) – GI: 45 | Sugar: 1.1g
- Macadamia Nuts – GI: 15 | Sugar: 4.6g
- Grapes (black) – GI: 43 | Sugar: 16g
- Kiwi – GI: 52 | Sugar: 8.9g
- Prunes – GI: 29 | Sugar: 38g
- Beets – GI: 30 | Sugar: 6.8g
- Parsnips – GI: 52 | Sugar: 5.6g
- Sour Cherries – GI: 22 | Sugar: 8g
- Grapes (red) – GI: 49 | Sugar: 16g
- Chia Seeds – GI: 35 | Sugar: 0g
- Whole Grain Bread – GI: 51 | Sugar: varies by brand
- Millet – GI: 54 | Sugar: 0.5g
- Pumpernickel Bread – GI: 50 | Sugar: 2.3g
- Sprouted Grain Bread – GI: 45 | Sugar: varies by brand
- Mango – GI: 51 | Sugar: 45.9g
- Spaghetti (whole grain) – GI: 42 | Sugar: 2.5g
- Buckwheat – GI: 54 | Sugar: 2.6g
- Steel-cut Oats – GI: 42 | Sugar: 1g
- Bran Cereal – GI: 50 | Sugar: varies by brand
- Cantaloupe – GI: 54 | Sugar: 7.9g
- Coconut Meat – GI: 45 | Sugar: 6g
- Tahini – GI: 25 | Sugar: 0.3g
- Nectarines – GI: 35 | Sugar: 7.9g
- Blueberries – GI: 53 | Sugar: 9.7g
- Pistachios – GI: 15 | Sugar: 7.7g
- Chickpea Pasta – GI: 42 | Sugar: 3.5g
Key takeaways: low glycemic diet for PCOS
Swapping out high GI foods for low GI foods may be beneficial for PCOS in regards to improving insulin resistance, lowering hyperandrogenism and improving period cyclicity. But, there are cons to the low glycemic diet for PCOS particularly in relation to the restrictive nature of the diet. As always, it is important to remember that every person is different and what works for one may not work for another. Avoid extreme restrictions and find a balance that works for you, working with healthcare professionals if possible.
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.