Nutrition in Polycystic Ovary Syndrome (PCOS): What Does the Evidence Actually Say?

Being diagnosed with Polycystic Ovary Syndrome (PCOS) often raises many questions, especially about food.

PCOS is not just about irregular periods or difficulty losing weight. It is a complex hormonal condition that affects women of reproductive age worldwide and is closely linked to metabolism, hormones, and long-term health.

Research shows that around 1 in 10 women before menopause experience PCOS. It was once thought to affect only adult women, but we now know that PCOS can appear from adolescence and even earlier, and it often continues throughout life.

PCOS is commonly associated with:

• Changes in ovarian structure and function

• Higher levels of male-type hormones (androgens)

• Insulin resistance

  
  

Because of these factors, PCOS is also linked to a higher risk of:

• Type 2 diabetes

• Metabolic syndrome

• Cardiovascular disease

• Depression and anxiety

This is why nutrition plays a central role in managing PCOS.

Why Insulin Resistance Matters in PCOS

One of the most important features of PCOS is insulin resistance. Studies estimate that about 75% of women with PCOS have some degree of it.

Normally, insulin helps:

• Control blood sugar levels

• Support energy use in muscles and other tissues

• Regulate fat storage and breakdown

When insulin resistance develops, the body needs to produce more insulin to do the same job. This leads to high insulin levels in the blood, which affects much more than blood sugar.

In women with PCOS, high insulin levels can stimulate the ovaries to produce more androgens, disrupt hormonal balance, and interfere with ovulation. Insulin also reduces the liver’s ability to regulate free testosterone levels. Over time, this may lead to irregular menstrual cycles, acne or excess hair growth, hair thinning, difficulty managing weight, and a higher risk of glucose and lipid abnormalities.

Excess body fat, especially around the abdomen, can further worsen this cycle. Fat tissue promotes low-grade chronic inflammation, which reduces insulin sensitivity and reinforces the metabolic imbalance seen in PCOS.

Importantly, insulin resistance can also be present in normal-weight women with PCOS, which means PCOS is not just a weight-related condition.

What Is the Goal of Nutrition in PCOS?

There is currently no single, definitive treatment for PCOS. Medical therapies often focus on managing symptoms, but lifestyle especially nutrition remains a cornerstone of care.

The main nutritional goals in PCOS are to:

• Improve insulin sensitivity

• Support metabolic and reproductive health

• Reduce long-term risks such as diabetes and cardiovascular disease

• Support weight management when excess body fat is present

  
  

Studies show that many women with PCOS tend to:

• Consume more calories and saturated fat

• Eat less fiber

• Follow diets higher in simple carbohydrates and glycemic load

  
  

Higher carbohydrate intake and diets with a high glycemic index have been linked to a greater risk of ovulation-related infertility.

Another important point: women with PCOS have a higher risk of disordered eating. For this reason, nutrition strategies should focus on long-term health and balance, not extreme restriction.

International guidelines recommend:

• A healthy lifestyle for all women with PCOS, and

• Weight-loss-oriented dietary approaches only when overweight or obesity is present.

Why the Mediterranean Diet Works Well for PCOS

Among different dietary patterns, the Mediterranean diet stands out as one of the most evidence-based options for PCOS. It is known for its

• anti-inflammatory and antioxidant effects,

• positive impact on insulin sensitivity,

• and its protective role against metabolic and cardiovascular diseases.

This eating pattern focuses on vegetables, fruits, whole grains, legumes, nuts, and seeds, with olive oil as the main fat source, regular fish consumption, moderate amounts of dairy and poultry, and limited red meat. Herbs and spices are commonly used instead of excess salt.

Research shows that women with PCOS often consume fewer complex carbohydrates and less fiber, lower amounts of healthy fats such as olive oil and omega-3s, and more simple sugars and saturated fats. Lower adherence to the Mediterranean diet has been linked to more severe PCOS symptoms.

Mediterranean Diet with Lower Carbohydrates

In a 12-week clinical study involving overweight women with PCOS, a Mediterranean-style diet with reduced carbohydrate intake led to improvements in:

• Body measurements

• Hormonal balance

• Insulin resistance

• Blood lipid levels

• Menstrual regularity

Compared with a traditional low-fat diet, this approach showed stronger overall benefits.

For many women with PCOS, especially those who are overweight, this type of eating pattern offers a balanced and sustainable option.

What About the Ketogenic Diet?

The ketogenic diet is very low in carbohydrates, higher in fat, and designed to shift the body into a state of nutritional ketosis.

Short-term studies in women with PCOS suggest that ketogenic diets may:

• Reduce body weight and fat mass

• Improve insulin resistance

• Lower androgen levels

• Improve some reproductive hormone markers

Modified ketogenic approaches, including Mediterranean-style versions, have shown similar short-term improvements.

However, PCOS is a long-term condition, and there are concerns about maintaining a ketogenic diet over long periods. Some evidence suggests that prolonged use may negatively affect metabolic health.

For this reason, ketogenic diets may be considered:

• Short-term,

• Under professional supervision,

• In selected cases, rather than as a universal solution.

The Bigger Picture: Individualization Matters

PCOS does not look the same in every woman. Some struggle mainly with fertility, others with metabolic health, hormonal symptoms, or psychological well-being.

Even women with normal body weight may have:

• Higher visceral fat

• Insulin resistance

• Metabolic challenges

This means that nutrition plans should always be individualized. Not only focused on weight loss, but also on body composition, metabolic health, and quality of life.

In Summary

PCOS is a long-term condition, not something that can be “fixed” with a short-term diet.

The most effective nutritional approach is one that:

• Improves insulin sensitivity

• Supports hormonal balance

• Is realistic and sustainable

• Fits into everyday life

If you have PCOS and feel confused about what to eat, you’re not alone. Working with a dietitian can help turn scientific knowledge into a plan that actually works for you.

References

Di Lorenzo, M., Cacciapuoti, N., Lonardo, M. S., Nasti, G., Gautiero, C., Belfiore, A., Guida, B., & Chiurazzi, M. (2023).Pathophysiology and nutritional approaches in polycystic ovary syndrome (PCOS): A comprehensive review. Current Nutrition Reports, 12, 527–544.