Ethnic Variability in Anthropometric Trajectories Across the Lifespan: Findings From a Nationwide Survey in Peru

Introduction: Anthropometric indicators are widely used for nutritional assessment and cardiometabolic risk, but their age-related patterns may differ by ethnicity, potentially limiting the applicability of global thresholds. To examine age-related trajectories of BMI and seven nonconventional anthropometric indicators by ethnicity in Peruvian adults. Methods: A cross-sectional analysis was conducted using nationally representative data from the 2021–2023 Demographic and Health Survey (ENDES). Adults aged 20–80 years with complete anthropometric data and self-reported ethnicity (Quechua-Aymara, Afro-Peruvian, Other) were included (n = 77 592). Eight indicators were analyzed: BMI, tri-ponderal mass index (TMI), a body shape index (ABSI), body roundness index (BRI), relative fat mass (RFM), weight-adjusted waist index (WWI), waist-to-BMI ratio, and conicity index. Generalized Additive Models for Location, Scale, and Shape (GAMLSS) were used to estimate smoothed percentile curves (3rd, 50th, and 97th) across age and ethnicity. Results: Percentile curves revealed distinct age-related trajectories by ethnicity. Quechua-Aymara men had lower values across percentiles for BMI, TMI, RFM, and BRI, but not consistently for ABSI, WWI, and conicity index. In women, patterns were more heterogeneous, with earlier and lower peaks for Quechua-Aymara at lower percentiles, while Afro-Peruvian and Other women showed gradual increases. For ABSI, WWI, and conicity index, men showed a linear increase with age, while women showed rising trajectories only at the upper percentiles. The waist-to-BMI ratio displayed a J-shaped pattern in both sexes, with more ethnic variability at lower percentiles in women. Conclusion: Ethnic disparities in anthropometric trajectories highlight the limitations of global thresholds and support the need for population-specific reference standards.