The PCOS Diet: What Does the Science Say?

Article produced by Mrs Emily Reilly Advanced Dietitian | RD, MNutr

Many people have heard of PCOS, but it remains widely misunderstood. You may have read that diet plays an important role, but it is not always clear why nutrition matters or what evidence-based dietary changes actually help.

You may also see the term PMOS (polyendocrine metabolic ovarian syndrome) being used in some clinical discussions. This is an emerging term intended to better reflect the metabolic and hormonal nature of the condition. However, PCOS (polycystic ovary syndrome) remains the most widely used and recognised term in clinical practice and research, so both terms are often used interchangeably.

At LycaHealth Orpington, our specialists take a holistic, evidence-based approach to PCOS management, including lifestyle, hormonal and metabolic health.

What is PCOS?

PCOS is one of the most common hormonal conditions affecting women of reproductive age. Despite the name, it is not simply a condition involving ovarian cysts. Instead, it is a complex endocrine and metabolic condition that can affect:

• Hormone balance
• Ovulation and fertility
• Metabolism and weight regulation
• Long-term metabolic health

The World Health Organization estimates that up to 70% of women with PCOS may remain undiagnosed globally, highlighting the importance of awareness and early diagnosis.

Common symptoms of PCOS may include:

• Irregular, absent or heavy periods
• Difficulty managing weight
• Increased cravings, particularly for carbohydrates or sugar
• Acne or oily skin
• Hair thinning or hair loss
• Excess hair growth (hirsutism)
• Insulin resistance and elevated blood sugar
• Fertility challenges

Symptoms vary significantly between individuals, which is why personalised management is essential.

PCOS and weight regulation

Not everyone with PCOS experiences weight gain, but for some, hormonal changes can make weight management more difficult.

Higher levels of androgens (such as testosterone) may promote fat storage, particularly around the abdominal area. In turn, excess body fat can further disrupt hormone balance, creating a self-reinforcing cycle that can be difficult to break.

Research suggests that improving diet quality and supporting insulin sensitivity can help interrupt this cycle. Even modest weight changes (5–10%) may improve metabolic and hormonal markers in some individuals.

Weight and metabolic health don’t only affect reproductive hormones — they can also impact other organs, including the liver. One example is MASLD (metabolic dysfunction–associated steatotic liver disease), previously known as fatty liver disease, which is increasingly linked with insulin resistance and weight changes.

This reflects the overlap between metabolic and liver health, and is discussed further in our article on fatty liver and weight management.

This reflects the overlap between metabolic and liver health, and is discussed further in our article on fatty liver and weight management.

Insulin resistance and blood sugar control

One of the most important metabolic features of PCOS is insulin resistance.

Insulin is a hormone that helps move glucose (sugar) from the bloodstream into cells for energy. When cells become less responsive to insulin, the pancreas produces more, leading to elevated insulin levels.

High insulin levels may:

• Increase fat storage
• Stimulate androgen production
• Worsen acne, irregular periods and excess hair growth
• Increase long-term risk of type 2 diabetes

Diet strategies that may help include:

• Choosing low glycaemic index (GI) carbohydrates
• Increasing fibre intake
• Including protein with each meal
• Reducing ultra-processed foods
• Supporting regular meal patterns to stabilise blood sugar

For more information on blood sugar regulation, see our related guide on prediabetes. 

Hormonal imbalance in PCOS

PCOS is associated with changes in several hormones, including:

• Testosterone
• Oestrogen
• Luteinising hormone (LH)
• Anti-Müllerian hormone (AMH)
• Sex hormone-binding globulin (SHBG)

While nutrition cannot cure hormonal imbalance, evidence suggests diet can support hormonal regulation indirectly—particularly through improving insulin sensitivity and reducing inflammation.

Dietary patterns that support hormonal health include:

• High-fibre diets (vegetables, legumes, whole grains)
• Healthy fats (olive oil, nuts, seeds, oily fish)
• Adequate protein intake
• Minimising highly processed foods

Inflammation and gut health

Research shows that people with PCOS often have increased low-grade inflammation, which may contribute to metabolic and hormonal symptoms.

One contributing factor may be advanced glycation end products (AGEs), which form during high-temperature cooking methods such as frying or grilling.

A diet that may help reduce inflammation includes:

• A wide variety of fruits and vegetables
• Whole grains and legumes
• Fermented foods that support gut health
• Antioxidant-rich foods (berries, leafy greens, spices)

Emerging research also highlights the role of the gut microbiome in metabolic health, insulin sensitivity and inflammation regulation.

Long-term health considerations

PCOS is not only a reproductive condition. It is also linked to long-term metabolic and cardiovascular health risks, including:

• Type 2 diabetes
• High cholesterol
• Cardiovascular disease
• Non-alcoholic fatty liver disease

Mental wellbeing is also an important consideration. Symptoms such as weight changes, fertility challenges, acne or hair loss can significantly affect emotional health and quality of life.

A holistic, multidisciplinary approach is often the most effective.

What about supplements for PCOS?

The supplement market for PCOS can feel confusing, with many products making unsupported claims.

Some supplements have emerging evidence for supporting:

• Insulin sensitivity
• Hormonal balance
• Ovulation support
• Inflammation reduction

However, responses vary significantly between individuals. Supplements should always be considered alongside:

• Blood test results
• Medical history
• Symptoms and lifestyle factors

It is important to discuss any supplements with a qualified healthcare professional before starting.

The bottom line

There is no single “PCOS diet” that works for everyone.

However, research consistently shows that nutrition can play a meaningful role in:

• Supporting insulin sensitivity
• Improving metabolic health
• Reducing inflammation
• Helping manage symptoms

The most effective approach is individualised, sustainable and evidence-based, tailored to each person’s symptoms, goals and metabolic profile.

About the author

   Mrs Emily Reilly, Advanced Dietitian | RD, MNutr

Emily is a Registered Dietitian with extensive experience across NHS and private healthcare. She holds a Master’s in Nutrition and Dietetics from The University of Nottingham and has undertaken additional specialist training in gastroenterology and advanced clinical nutrition.

Emily has particular expertise in women’s health, PCOS, fertility, gut health and weight management. Her approach combines evidence-based nutrition with personalised support to help patients make sustainable, long-term improvements to their health and wellbeing.

Book an appointment with Emily