Prevalence and Temporal Trends of Metabolic Syndrome and Dietary Associations Among U.S. Women: NHANES 2013–2023

BACKGROUND: Metabolic syndrome and related abnormalities, including insulin resistance and hyperinsulinemia, remain critical public health challenges, particularly among women. However, recent nationwide trends and diet-related determinants have not been fully explored. METHODS: 4,426 women aged ≥18 years from the 2013-2023 National Health and Nutrition Examination Survey were included. Metabolic syndrome (MetS) was defined according to NCEP ATP III, WHO, and International Diabetes Federation criteria. Additional outcomes included elevated hemoglobin A1c (HbA1c ≥ 5.7%), hyperinsulinemia (≥10 μU/mL), and IR (HOMA-IR ≥ 2.6). Survey-weighted logistic regression and generalized structural equation modeling were used to examine temporal trends and dietary associations, adjusting for race/ethnicity, menopausal stage, physical activity, and energy intake. RESULTS: Overall prevalence of MetS remained around 20%, whereas IR and hyperinsulinemia affected over 40% of women, peaking during 2017-2020. Later menopausal stages were strongly associated with higher odds of MetS, IR, and hyperinsulinemia. Moderate-carbohydrate diets became more common. Low-carbohydrate diets, which remained rare (<2%), were associated with lower odds of elevated HbA1c (odds ratio [OR] = 0.40, 95% confidence interval [CI]: 0.15-1.00) and hyperinsulinemia (OR = 0.35, 95% CI: 0.14-0.87). Higher fiber and monounsaturated fatty acid intakes were inversely associated with MetS and insulin-related markers, whereas greater omega-6 fatty acid intake and higher omega-6:omega-3 ratios were positively associated with insulin resistance. Elevated protein intake was protective among perimenopausal and naturally menopausal women. CONCLUSIONS: Between 2013 and 2023, U.S. women exhibited persistently high rates of metabolic abnormalities, with risk increasing across menopausal stages. Low-carbohydrate diets with higher fiber, monounsaturated fat, protein, and lower omega-6:omega-3 ratios were associated with improved metabolic health.