Age Cohort Patterns of Socioeconomic Inequalities in High Risk Body Mass Index (BMI) and Waist to Hip Ratio (WHR) Composite: Findings from Nationally Representative Survey

Background Obesity is a growing global health challenge, with central adiposity posing particularly high cardiometabolic risk. In low- and middle-income countries (LMICs) like India, the coexistence of undernutrition and obesity reflects a double burden of malnutrition. However, limited research has examined how socioeconomic inequalities in high-risk adiposity vary across age cohorts using combined anthropometric measures. Aim To assess age-cohort patterns of socioeconomic inequalities in high-risk adiposity defined using a composite of body mass index (BMI) and waist-to-hip ratio (WHR) in a nationally representative Indian population. Methods We analysed data from Wave-1 (2017–2018) of the Longitudinal Ageing Study in India (LASI), including 65,150 adults with complete anthropometric and socioeconomic data. High-risk body composition (BWC) was defined as overweight BMI with high-risk WHR, or obese BMI with any WHR. Descriptive, regression, and inequality measures (CI and Erreygers CI with decomposition) were used to examine disparities by socioeconomic status across age cohorts. Results The 18–44 cohort had the highest prevalence of overweight (28.4%) and obesity (10.9%), while WHR increased sharply with age (p < 0.001). Nearly all overweight (93%) and obese (91.6%) individuals were WHR high-risk. High-risk BWC was more common among women, urban residents, and individuals with higher education and wealth (p < 0.001). Inequality analysis showed a pro-rich concentration in all cohorts, peaking at ages 45–59 (ECI: 0.214), with education as the largest contributor (24–30%). Conclusion High-risk adiposity in India is patterned by age and SES. WHR captures substantial central obesity risk, highlighting the need for equity-focused, life-course obesity prevention strategies.