Objective Our objective was to test whether food insecurity mediates cross‐sectional associations between social disadvantage and body composition among older adults (aged 50+) in India (n = 6556). Methods Adjusting for key sociodemographic and dietary variables, we examined whether markers of social disadvantage (lower educational attainment, lower household wealth, belonging to a disadvantaged caste/tribe, and belonging to a minority religion) were associated with food insecurity. We then examined whether food insecurity, in turn, was associated with anthropometric measures of body composition, body mass index (BMI), and waist circumference (WC). We also tested whether food insecurity mediated the relationship between social disadvantage and body composition. Results In adjusted models, lower household wealth [lowest quintile (Q5) vs highest quintile (Q1): odds ratio (OR) = 13.57, P < .001], having less than a high‐school education (OR = 2.12. P < .005), being Muslim (OR = 1.82, P < .001), and being in a scheduled caste (historically marginalized) (OR = 1.49, P < .005) were associated with greater food insecurity. Those who were severely food insecure had greater odds of being underweight (OR = 1.36, P < .01) and lower odds of high WC (OR = 0.70, P < .01). Mediation analyses estimated that food insecurity explained 4.7%–29.7% of the relationship between social disadvantage and body composition, depending on the variables considered. Conclusions Our results are consistent with the hypothesis that food insecurity is a mechanism linking social disadvantage and body composition among older adults in India. These analyses contribute to a better understanding of processes leading to variation in body composition, which may help enhance the design of interventions aimed at improving population nutritional status.