Transition of obesity in India, 2006–2021: a state-wise investigation from an equity perspective

INTRODUCTION: Obesity and its downstream non-communicable diseases (NCDs) are the greatest health challenges of the 21st century, even in low-income and middle-income countries such as India. As traditional diseases of poverty wane, obesity and NCD burden rise. A crucial lens for understanding this transition is nation/state-wise 'economic gradient' of obesity. Therefore, we aimed to study the socioeconomic gradient of obesity and its changes (2006-2021) across India's major states vis-à-vis their varying prosperity from an equitable policy perspective. METHODS: We analysed data from non-pregnant women aged 15-49 years from National Family Health Surveys (NFHS-3 in 2006 and NFHS-5 in 2021), excluding the North-Eastern states and Union Territories. Obesity was defined as body mass index ≥25 kg/m². State-wise economic gradient was quantified using Slope Index of Inequality (SII) based on state-level wealth quintiles, assessed using gross state domestic product (GSDP). We examined associations between GSDP and both obesity prevalence and SII in both time periods. RESULTS: Obesity prevalence increased in all states as well as nationally between 2006 and 2021 (12.3% in NFHS 3 to 23.6% in NFHS 5), but the economic gradient neither flattened nor reversed. The association between GSDP and obesity prevalence remained positive. However, the relationship between GSDP and SII (r=0.69, p=0.001 in 2006 to r=0.05, p=0.8 in 2021) weakened over time in wealthier states and steepened in poorer ones. CONCLUSIONS: Despite its ubiquitous growth, obesity was (2006) and remains (2021) concentrated among the rich in every state, though states are at varying stages of obesity transition. While none have experienced reversal of the economic gradient, green shoots of reversal are evident in affluent states through weakening of their economic gradients, while gradients intensified in poorer ones. These findings underscore the need for nuanced, state-specific strategies to ensure equitable distribution of healthcare resources to address rising obesity and NCD epidemic, without neglecting the unfinished agenda of communicable diseases.