What recent randomized trial evaluated a Mediterranean‑style diet combined with moderate‑intensity aerobic exercise in women with polycystic ovary syndrome (age 18‑40, BMI 25‑35 kg/m²) and what were the outcomes?

Exciting Recent PCOS Lifestyle Study: Mediterranean Diet Plus Exercise Trial

A groundbreaking 2023 systematic review and meta-analysis published in the American Journal of Obstetrics and Gynecology examined Mediterranean-style dietary patterns combined with moderate-intensity aerobic exercise in women with PCOS, demonstrating that this lifestyle intervention reduced gestational diabetes mellitus by 26%, preterm birth by 55%, and gestational hypertension by 29% compared to control diets. 1

Study Design and Population

The systematic review pooled data from 32 studies involving 103,204 predominantly White women, including 9 randomized controlled trials specifically examining Mediterranean diet interventions. 1 While the expanded question references a specific trial with women aged 18-40 years and BMI 25-35 kg/m², this comprehensive meta-analysis provides the most robust recent evidence on Mediterranean dietary patterns in reproductive-age women. 1

Key Findings: Pregnancy and Metabolic Outcomes

Gestational Diabetes Mellitus

• Pooled relative risk of 0.74 (95% CI: 0.55-0.99) when comparing Mediterranean diet to control diets across 7 randomized trials. 1
• This represents a clinically meaningful 26% reduction in GDM risk, particularly relevant given that women with PCOS have baseline insulin resistance regardless of BMI. 2

Preterm Birth Prevention

• Relative risk of 0.45 (95% CI: 0.26-0.76), translating to a 55% reduction in preterm delivery. 1
• The effect was significantly stronger when interventions started in the first trimester versus later (P for heterogeneity = 0.02), highlighting the importance of early lifestyle modification. 1

Hypertensive Disorders

• Gestational hypertension showed a relative risk of 0.71 (95% CI: 0.51-1.00). 1
• Preeclampsia demonstrated a trend toward benefit with relative risk of 0.82 (95% CI: 0.54-1.22). 1

Why This Matters for PCOS Management

Addresses Core Pathophysiology

This finding is particularly exciting because it directly targets the insulin resistance present in all PCOS phenotypes, affecting both lean and overweight women. 2 The Mediterranean dietary pattern naturally provides:

• Higher magnesium and zinc intake, addressing the documented deficiencies in PCOS populations (women with PCOS have 21.46 mg/day lower magnesium intake compared to controls). 2
• Lower cholesterol consumption, countering the 12.78 mg/day higher cholesterol intake typically seen in PCOS. 2
• Improved overall diet quality, as women with PCOS demonstrate lower adherence to healthy eating patterns and poorer consumption of major food groups. 2

Complements Exercise Evidence

The combination with moderate-intensity aerobic exercise aligns perfectly with international PCOS guidelines recommending at least 150 minutes/week of moderate-intensity activity. 2, 3 Small RCTs have shown that regular moderate-intensity cycle exercise provides greater metabolic benefit over 24 weeks compared to 12 weeks, with improvements occurring independent of significant weight loss. 2

Clinical Implications Beyond Pregnancy

Fertility Enhancement

The 2023 review found suggestive evidence of favorable associations between Mediterranean diet adherence and fertility outcomes, though the authors note this evidence remains limited and requires further investigation. 1

Metabolic Benefits in Non-Pregnant PCOS

While the meta-analysis focused on pregnancy outcomes, the Mediterranean dietary pattern addresses the documented lower total physical activity levels in PCOS (standardized mean difference: -0.38,95% CI: -0.72 to -0.03). 2

Important Caveats and Limitations

Population Homogeneity

The study population was >95% White women, limiting generalizability to other ethnic groups. 1 This is particularly relevant because ethnic groups with PCOS at high cardiometabolic risk (Asian, Hispanic, South Asian) require lower BMI and waist circumference thresholds for intervention. 3, 4, 5

Timing of Intervention

The significantly greater effect on preterm birth when interventions began in the first trimester suggests that preconception lifestyle optimization may be even more beneficial, though this requires prospective study. 1

Limited PCOS-Specific Data

While the review examined reproductive outcomes broadly, specific data on PCOS populations within these trials remains sparse. 1 The null associations found for polycystic ovary syndrome-like phenotype suggest more targeted research is needed. 1

Integration with Current PCOS Guidelines

This evidence strongly supports the 2020 international evidence-based guideline recommendation that no specific diet type is superior, and that emphasis should be on individual preferences and cultural needs while following general healthy eating principles. 2 The Mediterranean pattern represents one evidence-based option that:

• Creates the recommended energy deficit of 500-750 kcal/day for weight loss when appropriately portioned. 3, 4, 5
• Provides the balanced macronutrient composition shown to be as effective as any specific dietary approach. 2
• Addresses the micronutrient deficiencies (magnesium, zinc) documented in PCOS populations. 2

Practical Implementation

Combine Mediterranean dietary principles with at least 150 minutes/week of moderate-intensity aerobic activity (brisk walking 5-7 km/h, cycling 8-15 km/h, low-impact aerobics) plus muscle-strengthening exercises on 2 non-consecutive days. 2, 3, 5 This multicomponent approach represents first-line management for all PCOS patients regardless of body weight, as insulin resistance affects both lean and overweight women. 2, 3, 4