To address the causes for obesity in all of China is not feasible in a single article. There are hundreds of ethnic groups over a vast number of provinces. The diet and lifestyle of each is different based upon cultural/ethnic traditions and the environment. Several studies mentioned in this review have been done in particular areas and/or on specific population groups with regards to obesity and health risks associated with being overweight. Obesity is a multifactorial disease that is associated with genetic, physiological, environmental, and cultural/traditional perspectives in order to provide a broadened view on this epidemic in China. In this review, we will assess specific obesity gene and environment interactions, childhood obesity etiology, metabolic syndrome, and dietary and behavioral causes. We attempt to discuss obesity issues particularly in the Han Chinese population ranging from children, adolescents, adults to geriatrics.