Population trends in nutritional status and socioeconomic divergence in extreme obesity in Peru: geospatial dynamics...

Peru is undergoing a sustained nutrition transition; however, evidence on the simultaneous behavior of extreme phenotypes - geriatric underweight and class III obesity - and their generational determinants remains limited. We aimed to analyze the temporal, geospatial, socioeconomic, and intergenerational dynamics of population malnutrition over the last decade.

This was a repeated cross-sectional, population-based analytical trend study with age-period-cohort (APC) analysis, using data from the Peruvian Demographic and Family Health Survey (DHS) 2014-2024 (excluding 2020), including 257,264 individuals aged ≥15 years. Nutritional status was assessed using body mass index (BMI) and life-stage-specific cut-offs (adolescents: 2007 World Health Organization BMI-for-age Z-scores; adults: World Health Organization BMI criteria; older adults: Pan American Health Organization/Salud, Bienestar y Envejecimiento and Peruvian Ministry of Health criteria). Temporal trends were estimated using average annual percent change (AAPC) from weighted log-linear regressions. Economic inequality was quantified with the Erreygers Concentration Index (ECI). Generational risk was estimated through an APC model restricted to adults aged 20-80 years for class III obesity (BMI ≥40 kg/m²).

Among adults, normal weight prevalence fell markedly (AAPC -3.4%/year; p < 0.001), while class III obesity showed the largest proportional increase (+8.9%/year; p < 0.001). Underweight remained close to 20% in older adults by 2024, reflecting a persistent geriatric double burden. ECI showed that extreme obesity, initially concentrated in wealthier quintiles, spread toward lower and middle strata, though the pro-rich gradient persisted (ECI 2014: 0.008; ECI 2024: 0.011; both p = 0.002). Cohorts born in the 1990s and 2000s showed substantially higher relative rates of class III obesity compared with the 1970 reference cohort at equivalent biological age, reflecting a marked unfavorable generational shift.

Peru exhibits a divergent double burden of malnutrition. The rise in class III obesity spans multiple socioeconomic strata, disproportionately affects recent cohorts, and coexists with persistently high underweight in the geriatric population.