The prevalence of overweight and obesity in India has increased substantially in recent decades, and Indians are particularly predisposed to diabetes. Despite this, recent trends in the socioeconomic patterning of overweight and obesity are currently unknown, and reliable future forecasts of overweight, obesity and diabetes to assist policy makers are over-simplistic. The main aims of this thesis were to: (I) examine recent trends in the socioeconomic patterning of overweight and obesity in India, (II) estimate the future prevalence of overweight, obesity and diabetes to 2040, and (III) estimate residual lifetime risk of diabetes. The first objective was addressed using multilevel regression analysis, and the second and third by building dynamic simulation models. Input data were extracted from national surveys, census demographic data and community level cohort studies. The research identified considerably greater increases in overweight and obesity prevalence between 1998 and 2016 in poorer, compared to richer, socioeconomic groups particularly in urban areas, the most economically developed states, and among women. Among 20-69-year-old Indians, overweight and obesity prevalence is forecast to reach 30% and 10% among men, and 27% and 14% among women by 2040. The resultant prevalence of diabetes among urban men and women, respectively, in 2040 is expected to reach 27% and 25%. The lifetime probability of developing diabetes at 20 years among urban men and women is 69% and 75%, respectively, however is considerably higher among the obese population. This thesis marks the most recent attempt to identify the trends in the socioeconomic patterning of excess weight in India, the most thorough attempt to forecast future overweight, obesity and diabetes, and the first to examine the lifetime risk of diabetes. These findings are intended to guide future policy and monitor progress goals related to both excess weight and diabetes.