Polycystic ovary syndrome (PCOS) affects up to 15–20% of women of reproductive age (1).
It occurs when levels of certain hormones are out of balance, leading to the growth of fluid-filled sacs on the ovaries.
Side effects include irregular or absent periods, hair loss, excess hair growth, acne, weight gain, depression and fertility problems.
PCOS is also associated with a higher risk of type 2 diabetes, heart disease and obesity (2).
Unfortunately, there is no cure for PCOS. However, one of the first-line treatments is diet and lifestyle changes.
Below are 7 evidence-based dietary tips that can relieve symptoms and boost weight loss in women with PCOS.
1. Try a Low-GI Diet
Insulin is a hormone that transports sugar from your blood into your cells for energy or storage.
However, a low-glycemic index diet can help keep insulin levels stable.
The glycemic index (GI) is a measure of how quickly a food raises blood sugar levels. A low-GI diet consists of eating foods that raise blood sugar levels slowly, which helps prevent insulin spikes.
The low-GI diet usually consists of eating whole fruits and vegetables, whole grains, lean protein and healthy fats. It also involves avoiding most processed or refined carbs, including sugary foods and drinks.
One study found that menstrual regularity improved in 95% of women on a low-GI, weight loss diet, compared to 63% of women on a standard weight loss diet (7).
Another study including 60 overweight women with PCOS found that following a high-protein, low-GI, weight loss diet improved insulin sensitivity and reduced levels of inflammatory markers, compared to a standard weight loss diet (8).
Summary: A low-GI diet can help restore irregular periods, reduce inflammatory markers and improve insulin sensitivity in women with PCOS.
2. Don’t Skimp on Breakfast
Women with PCOS are encouraged to eat regular meals.
A study found that making breakfast the biggest meal and dinner the smallest may help balance out the hormones associated with PCOS.
For normal-weight women with PCOS, eating almost half of their daily calories at breakfast reduced insulin levels by 8% and testosterone levels by 50% over 90 days.
In addition, these women ovulated 30% more often than women who ate a smaller breakfast and larger dinner, suggesting improved fertility (9).
However, it’s important to note that increasing the size of your breakfast without reducing the size of your evening meal is likely to lead to weight gain.
Moreover, this was only one study including 60 women, so further research is needed to prove the benefits of making breakfast your biggest meal of the day.
Summary: Eating a larger breakfast and smaller evening meal may help improve hormone levels and improve ovulation in women with PCOS. However, more research is needed.
3. Eat Enough Healthy Fats
Some healthy fats include oily fish, avocados, olive oil and unsalted nuts and seeds.
One study involving 61 women with PCOS found that supplementing with omega-3 fatty acids over eight weeks improved insulin resistance by around 22% (11).
Similar results were found in another study in which supplementing with omega-3 fatty acids and vitamin E for 12 weeks led to improved insulin resistance and a reduction in testosterone levels in women with PCOS (12).
Even without omega-3 supplements, adequate intake of healthy fats may also improve insulin resistance.
For example, one study found that replacing some carbs with unsaturated fats resulted in reduced blood insulin levels in obese women with PCOS (13).
However, to avoid weight gain, try to replace unhealthy fats from processed or fried foods with healthy fats, rather than adding extra into your diet.
Summary: An adequate supply of healthy fats like omega-3 fatty acids can help reduce blood insulin and testosterone levels and improve insulin resistance in women with PCOS.
4. Cut Down on Carbs
Reducing your carb intake may improve the hormonal imbalance linked to PCOS and boost weight loss in women with PCOS.
Insulin is produced as carbs are converted into glucose in the body.
One study showed that a moderate reduction in carb intake reduced blood insulin concentrations among women with PCOS (14).
Over time, this may improve PCOS symptoms.
Furthermore, in a group of 30 women with PCOS, a modest reduction in carbs had very positive effects on hormone levels.
These included reductions in blood sugar, blood insulin and testosterone levels, as well as improvements in insulin sensitivity (15).
These benefits aren’t just limited to a better hormone balance. A low-carb diet has also been shown to help boost weight loss.
For example, women on a low-carb diet lost slightly more weight than those on a conventional diet or a diet higher in monounsaturated fat (14).
Compared to a standard diet, a low-carb diet can lead to an additional 1–5% weight loss in women with PCOS (16).
The slightly greater weight loss associated with a low-carb diet may be due to the naturally higher protein and fat intake that it promotes. This can help reduce blood sugar levels, cravings and appetite, all while improving feelings of fullness (17, 18).
Alternatively, it may be that by reducing carbs, you naturally tend to follow a lower-GI diet, which can improve the hormonal effects of PCOS.
Summary: In women with PCOS, a moderate reduction in carbs reduces insulin and testosterone levels and improves insulin sensitivity. It may also result in slightly greater weight loss.
5. Eat Plenty of Lean Protein
Androgens, such as testosterone, are male sex hormones.
While women have androgens, levels of these hormones tend to be higher than normal in women with PCOS.
This partly explains some of the unpleasant side effects of PCOS, such as excess facial hair, a deeper voice and irregular periods.
One study found that free androgen levels were much lower in women with PCOS when following a high-protein diet (30% protein), compared to a low-protein diet (15% protein) (19).
Compared to high-carb foods, high-protein foods do not cause great increases in insulin levels.
As a result, a high-protein diet is likely to be much more filling and reduce insulin levels, both of which can have positive effects on PCOS symptoms.
Be sure to include plenty of healthy protein sources in your diet, such as lean meat, fish, eggs, beans and some dairy products.
Summary: In women with PCOS, consuming a higher-protein diet is associated with a reduced appetite, lower insulin and lower testosterone levels, compared to a higher-carb diet.
6. Stay Active
Regular exercise has many health benefits, especially for women with PCOS.
For example, one review found that key benefits included improved ovulation, reduced insulin resistance (up to 30%) and greater weight loss (up to 10%) (21).
In overweight and obese women with PCOS, body composition improved when exercise was combined with a weight loss diet (22).
One study found that among women with PCOS, exercising over a three-month period also reduced inflammatory markers (24).
This is important because chronic inflammation tends to be more common in women with PCOS and is linked to insulin resistance (25).
Summary: Regular exercise may improve insulin resistance and ovulation, help burn body fat and reduce inflammatory markers in women with PCOS.
7. Some Supplements May Be Helpful
Studies show that certain supplements may help ease the symptoms of PCOS, especially in women who have low levels of those nutrients.
Therefore, it’s often recommended that women with PCOS who are deficient in this vitamin take vitamin D supplements (28).
However, it has not been proven that vitamin D supplements will reduce these negative side effects. Therefore, more research is needed (27).
Interestingly, vitamin D deficiency is one of the most common deficiencies worldwide (29).
Its main source is the sun. If your levels of vitamin D are low and you don’t get much sun exposure, most health professionals will recommend taking a supplement.
Another nutrient that may help improve PCOS symptoms is chromium, an essential mineral that helps boost the action of insulin.
Chromium deficiency is a lot less common, as it is found in a wide range of foods.
Foods higher in chromium include shellfish, mussels, nuts and some fruits and vegetables, such as broccoli, pears and tomatoes.
One study found that supplementing with 1,000 mcg of chromium for two months improved insulin sensitivity by up to 38% in obese women with PCOS (30).
Yet, this study was very small, so more studies are needed to confirm this benefit.
Summary: Taking vitamin D and chromium supplements may help improve symptoms of PCOS, especially if women are deficient. However, more studies are needed to prove their benefits in those with PCOS.
The Bottom Line
While there is no cure for PCOS, choosing the right nutrition can lead to happy and healthy living.
If you are overweight, as little as a 5% weight loss has been proven to greatly improve PCOS symptoms (31).
Choosing low-GI foods, moderately reducing your carb intake, avoiding sugary foods and having a good intake of healthy fats and lean protein is a good place to start.
Regular exercise can provide major benefits, too.
By making good choices, you can take control of PCOS symptoms.