Relationship of Body Mass Index and Dietary Inflammatory Index With Free Androgen Index and Insulin Resistance in Women With Polycystic Ovary Syndrome.

Abstract

BACKGROUND: Polycystic ovary syndrome (PCOS) is a leading endocrine disorder in reproductive-aged women. While dietary interventions are widely advocated, the distinct roles of adiposity and dietary inflammation in driving PCOS phenotypes remain unclear. Therefore, this study aimed to dissect the contributions of body mass index (BMI) and dietary inflammatory index (DII) to hyperandrogenism and insulin resistance (IR) in PCOS. METHODS: This cross-sectional study included 115 women with PCOS who visited gynecology and infertility clinics affiliated with Tabriz University of Medical Sciences. Data from the DII were computed using a validated 168-item semi-quantitative food frequency questionnaire. The free androgen index (FAI) was calculated as follows: (total testosterone (nmol/L)/SHBG (nmol/L)) × 100. The relationships between the BMI and DII and FAI, the Homeostasis model assessment of insulin resistance (HOMA-IR), the Homeostasis model assessment of β-cell function (HOMA-β), the quantitative insulin sensitivity check index (QUICKI), sex hormone binding globulin (SHBG), testosterone, fasting insulin (FI), and fasting blood sugar (FBS) were assessed using descriptive and analytical statistics. The general linear model was applied to adjust for confounders. RESULTS: The mean (standard deviation, SD) BMI and FAI among subjects were 26.27 (3.82) kg/m(2) and 1.5 ± 1.5%, respectively. The median DII (range: -3.66 (most anti-inflammatory) to 4.31 (most pro-inflammatory)) was 0.75. Significant direct relationships were observed between the BMI and FAI (p < 0.001), HOMA-IR (p = 0.008), QUICKI (p = 0.002), testosterone (p < 0.001), FI (p = 0.017), FBS (p = 0.004), and Ferriman Gallwey score (p < 0.001). No significant associations were found between DII and the aforementioned biomarkers (p > 0.05). A normal BMI was associated with a significantly lower hirsutism score (β = -3.94, p = 0.003), fasting blood sugar (β = -10.02, p < 0.001), fasting insulin (β = -4.05, p = 0.042), HOMA-β (β = -1.20, p = 0.012), QUICKI (β = -0.19, p = 0.015), testosterone (β = -0.34, p < 0.001), and free androgen index (β = -0.96, p = 0.025) compared to an obese BMI after adjusting for confounders. No significant associations were observed for DII categories (median split) across any biomarkers or hirsutism. CONCLUSION: Adiposity (measured by BMI)-not dietary inflammation-was independently associated with key PCOS manifestations, demonstrating significant positive relationships with hyperandrogenism markers (FAI, testosterone), insulin resistance (HOMA-IR), and clinical hirsutism. A normal BMI was correlated with clinically meaningful reductions in metabolic-androgen parameters compared to obesity. Thus, weight loss and a generally healthy diet may need to be combined to impact PCOS features significantly.