AHA Scientific Sessions 2026 Abstract · Nov 2, 2026
Sex-Specific Trends in Waist Circumference and Body Mass Index Among US Adults: NHANES 1999-2023
By Corsi D, Patel D, Visaria A
Background: Worldwide obesity rates, as measured by body mass index (BMI), have more than doubled since 1990. Waist circumference (WC) is a simple measure of central adiposity that predicts cardiovascular and all-cause mortality independent of BMI, with the strongest associations emerging after BMI adjustment. Whether secular increases in WC have tracked with rising BMI, and whether trajectories differ by sex, has direct implications for population cardiovascular risk surveillance and individual clinical screening. Hypothesis: Secular increases in WC have outpaced BMI, with a meaningful proportion of the WC trend occurring independently of BMI. Methods: We analyzed serial National Health and Nutrition Examination Survey (NHANES) cycles from 1999-2000 through 2021-2023 in adults aged ≥20 years (n≈51,203). Age-standardized mean BMI and WC were estimated per cycle using survey weights and Taylor series linearization for variance. Ordinary least squares regression estimated the secular WC trend per cycle, adjusted for age and race/ethnicity, with and without BMI adjustment. Analyses were repeated in a metabolically healthy subcohort defined by Homeostatic Model Assessment of Insulin Resistance (HOMA-IR) <2.5. Women were additionally stratified by age (<55 vs ≥55 years). Results: Mean BMI rose by approximately 2 kg/m ² in both sexes (Figure 1). Women experienced 1.70-fold greater absolute WC gain than men (approximately 6.1 vs 3.5 cm, p<0.001) over the study period. BMI explained 87.7% of the secular WC trend in men, with no significant BMI-independent residual after adjustment. In women, 69.5% of the WC trend was explained by BMI, with a statistically significant BMI-independent residual persisting (p<0.001). The pattern was preserved in the HOMA-IR <2.5 subcohort, in which BMI accounted for 53.7% of the WC trend in women versus 77.0% in men, and was most pronounced in women ≥55 years (45.7% explained). Conclusions: Over two decades, US women have accrued central adiposity, as measured by WC, at a substantially higher rate than men, with a meaningful fraction of the WC increase occurring independent of BMI and persisting in metabolically healthy strata. These findings indicate a sex-specific shift in body fat distribution that BMI-based surveillance may obscure. They additionally support routine incorporation of WC and/or other measures of visceral adiposity into population-level cardiovascular risk monitoring and clinical assessment, particularly in women.