South Africa like many other developing countries is undergoing a rapid demographic and nutritional transition. While it continues to deal with the challenge of infectious diseases and child malnutrition, the upsurge in obesity and its accompanying non-communicable diseases present a new set of problems. This paper uses the National Income Dynamics Study to assess and quantify the prevalence of obesity and child malnutrition in South Africa, as well as give an account of the changes that have occurred in the past decade. It also examines a number of household and socio-economic indicators in an attempt to uncover the key determinants of obesity.