PCOS is a hormonal disorder that is closely tied to our metabolism, which is how our body turns glucose from what we consume into energy. What we eat not only determines the sugar levels in our blood, but also shapes how well we can absorb it and use it as fuel. This can influence how we experience PCOS, too.
If you have polycystic ovary syndrome (PCOS), you may have been told that a low-glycemic or low-carb diet may help the condition. While there is scientific evidence behind focusing on carbohydrate content, you might not know what this actually means or how to execute it. For example, how can these diets improve your symptoms, and how are you meant to implement them? Which foods are best for your PCOS?
To get these answers, we need to look at the science behind how our metabolism responds to different types of foods—and consider the evidence on how this affects PCOS.
Insulin and PCOS
Before we look at specific diets, we first need to understand the relationship between PCOS and insulin resistance.
One common feature of PCOS is an excess of androgens, or “male” hormones. High androgen levels can bring on symptoms like irregular or missed periods, acne, and excess hair growth on the face and body (hirsutism). Excess androgens can be caused and made worse by poor metabolic health—specifically, insulin resistance.
The relationship between androgens and insulin plays a significant role in PCOS. Most people with PCOS have insulin resistance—estimates currently sit at 50-90%.
Insulin’s job is to help the body process blood sugar (glucose) and turn it into energy or store it for later. When blood sugar rises, we produce more insulin to keep up. Our body can become less receptive to the effects of insulin if we make a lot of it over time—this is known as insulin resistance. The body then produces even more insulin to compensate. Excess insulin can interfere with how other organs release hormones, which can ultimately lead to increased androgen production.
On the flip side, too many androgens can also worsen insulin resistance by causing weight gain, especially around the belly. This additional fat tissue releases signals that impair our response to insulin, which can increase androgen levels, perpetuating this cycle. To make matters worse, insulin resistance can also directly cause weight gain, as it puts the body in a state where it more readily stores glucose as fat rather than use it as fuel.
For folks with PCOS, both raised androgen levels and insulin resistance cause changes in the body that result in unwanted symptoms, such as acne and facial hair, and increase the risk of other conditions, such as heart disease and infertility.
How dietary choices can bring down insulin resistance
Given the relationship between PCOS and insulin resistance, many medications and lifestyle strategies for PCOS focus on insulin and metabolic health. Thus, it is critical to understand how diet can influence insulin production when discussing PCOS.
We get three main types of nutrients from our diet: carbohydrates, proteins, and fats. Carbohydrates are the primary macronutrient that influences blood sugar. When we eat carbohydrates, the body breaks them down and converts them into sugar, or glucose, which then enters the blood to be used as fuel.
Not all carbs break down the same way, impacting our blood sugar differently. Some carbs break down fast, meaning they release glucose fast—causing blood sugar to rise quickly. Other foods break down slowly and have a more gradual impact on blood sugar.
Consistently eating foods that spike blood sugar increases insulin, contributes to insulin resistance, and ultimately exacerbates PCOS (as well as increases the risk of many other health conditions). Meanwhile, foods that have a more gradual effect on blood sugar can prevent the body from perpetuating this cycle of increased production of insulin and androgens.
Processed grains, potato products, and foods high in added sugar tend to spike blood sugar, while legumes, nuts, and non-starchy vegetables lead to more stable glucose levels. Fats and proteins have a minimal effect on blood sugar after eating. Here’s an extensive list of foods unlikely to spike blood sugar.
Can changing your diet help with PCOS?
Eating foods that help you maintain stable blood sugar can reduce insulin resistance. Research demonstrates this can help people with PCOS to lower androgen levels and improve PCOS symptoms.
In a review of 8 studies involving 412 overweight or obese people with PCOS, eating a low-glycemic diet (meaning eating foods that don’t typically spike people) effectively lowered both blood sugar and insulin levels. Testosterone levels also dropped, which reduced body hair growth and improved fertility.
One of these studies that specifically looked at fertility found that a low glycemic index (GI) diet helped to restore ovulation. After following a low-GI diet for three months, participants ovulated in 25% of their cycles, compared to 7% of those on a normal-GI diet.
Since eating for stable blood sugar often supports weight loss, this can further contribute to lowering insulin resistance as fat tissues can impair how well we absorb glucose. In one study, 62 women on a low-glucose diet lost around a pound per week. After 24 weeks, on average, they’d lost 8% of their body weight and had reduced insulin, blood sugar levels, and testosterone. Eighty percent had regular menstruation restored, while 32% had a reduction in acne.
The best diet strategies for PCOS
Eating a blood-sugar-friendly diet
When it comes to the right diet for PCOS, there is one clear path: you want to prevent your blood sugar from spiking after you eat.
Although fasting can be helpful for metabolic health, you don’t necessarily have to eat less food to see benefits from your diet. Simply switching to foods that help maintain stable blood sugar can help.
In a study of 61 women with PCOS, eating a low-GI pulse-based diet (lentils, beans, chickpeas) for 16 weeks reduced insulin resistance and caused a mean 12-pound weight loss. Pulses are around 60% carbs and contain complex carbohydrates as well as important vitamins and minerals like iron and zinc. Another paper found that reducing the GI of a diet without changing the total carbohydrate intake had the same impact on blood sugar as eating fewer carbs. Both reduced rises in blood glucose after eating.
Lowering the GL of your diet can be done in two ways: by reducing the number of carbohydrates you eat or changing the type of carbohydrates you eat. Many diets combine both, and there’s evidence that this works. In one study of 59 overweight people with PCOS, following a diet with an increased amount of protein and healthy fats for 12 weeks improved both blood sugar and insulin resistance, as well as the return of normal menstrual cycles.
Outside of focusing on carbohydrates, other supplemental strategies can help, such as increasing fiber, decreasing processed foods, focusing on micronutrient intake, and even potentially incorporating more vinegar into your diet.
For a few places to get started on eating for stable blood sugar, read more here:
- Why arguing about diets misses the point
- What is glycemic variability and why does it matter
- Improving insulin through diet: calories vs. carbs
- 9 essential elements of metabolically healthy meals
- 50 nutritious foods with metabolic health benefits
- 78 recipes unlikely to spike blood sugar
- The best and worst fruits for blood sugar
- 10 desserts less likely to spike blood sugar
- 10 of the worst foods for blood sugar according to CGM data
While what you choose to consume is highly important, there are a couple of other strategies you can put in place to make sure your blood sugar stays stable.
Eat earlier in the day
How well our body can process glucose from a meal can also vary depending on the time of day. Ever heard of your body clock or circadian rhythm? It’s the 24-hour rhythm your body follows as it anticipates the energy demands of your daily routine and prepares itself to respond.
Our glucose tolerance is highest in the morning when we need the energy to get up and start our day, and naturally lowers when our body expects that we’ll go to bed because sleep is a fasting state. So, eating your largest meal earlier in the day can help you meet your energy demands while keeping your blood sugar levels in check.
One study of 30 people with PCOS found that those eating a high-calorie meal for breakfast (980 cal) and then a medium-calorie lunch (640 cal) and low-calorie dinner (190cal) had a 54% reduction in insulin and 50% drop in testosterone compared to those who did it the other way around, with their low-calorie meal for breakfast.
This suggests that eating more when our body is better at converting glucose to energy reduces insulin resistance, but we need more evidence to make specific recommendations for PCOS treatment. For example, calories are only part of the picture. As described above, the impact a given food has on blood sugar likely also plays a role.
Go for a walk after you eat
Exercise increases our body’s demand for energy, which means that we absorb more glucose from the blood.
If you go for a walk after a meal, the glucose in the blood from what you’ve just eaten is taken up more quickly by the muscles, which can prevent blood sugar from surging. Even a moderate or slower walk increases energy expenditure and glucose uptake. Walking at a pace of 0.5 m/ph-3.5 m/ph for 30 minutes is enough to improve blood sugar levels and keep them more stable, for example. According to a 2016 review of 39 papers, the ideal window for getting yourself moving is 30-45 minutes after eating.
Diet is just one part of the picture
While what you eat is important, it isn’t everything. Other health factors can also have a significant impact on metabolic health. Focusing on getting quality sleep, lowering stress, and incorporating regular exercise can all play a role in optimizing metabolic health.