Exploratory associations of dietary factors and adiposity with insulin resistance markers in postmenopausal women

Postmenopausal women are at increased risk of insulin resistance (IR), driven by age-related changes in body composition, low-grade inflammation, and dietary patterns. However, the role of protein source, amino acid profile, and selected micronutrients in IR remains insufficiently characterized. The aim of this study was to identify dietary components associated with markers of insulin resistance in postmenopausal women using complementary IR indices. In this cross-sectional study of 179 postmenopausal women, insulin resistance was assessed using HOMA2-IR and the triglyceride–glucose (TyG) index, while lipid-related adiposity was evaluated using the lipid accumulation product (LAP). Dietary intake was assessed using validated 3-day food records. Associations between dietary variables and metabolic markers were examined using correlation and multivariable regression analyses adjusted for age, BMI, and total energy intake. In exploratory unadjusted analyses, insulin resistance markers were associated with higher reported intakes of total and animal protein and several amino acids, and with lower reported intakes of selected micronutrients. However, these associations were attenuated in multivariable models adjusted for age, BMI, and reported energy intake. BMI remained the only factor independently associated with HOMA2-IR (β = 0.29, 95% CI 0.16–0.43, p < 0.001), whereas the examined dietary variables were not independently associated with this outcome. Associations with the TyG index were weaker after correction for multiple comparisons, and no dietary correlations with LAP remained significant after false discovery rate correction. Sensitivity analyses additionally accounting for parent study project, education, and physical activity, as well as an alternative model using waist circumference instead of BMI, did not materially alter the principal findings. These findings indicate that adiposity was the dominant independent correlate of insulin resistance in this sample.