This overview describes the study of obesity issues over the last 8 years in Mainland China. A disease risk-based body mass index classification for Chinese adults was developed and verified by the results of the 2002 China Nationwide Nutrition and Health Survey. Age and gender-specific BMI cut-offs for Chinese children and adolescents aged 7–18 years were also developed. As the first step in the obesity control effort, the public health implications of the prevalence of overweight and obesity were set out and publicized by the government of China. The overweight prevalence in 2002 was 22.8% and for obesity 7.1%, these having increased by 40.7% and 97.2%, respectively, since 1992. In children, dramatic increases in overweight/obesity have occurred with a two- to threefold increase in Beijing and Shanghai between 1985 and 1995; the prevalence of overweight plus obesity in 7- to 12-year-old boys approached 29% in 2000 and in girls 15–17%. The rapid development of overweight/obesity in China will undoubtedly push up the prevalence of chronic disease. The relative risk for adult hypertension and diabetes in the overweight and obese populations was 2–5 in 2002. In adolescents, the relative risk of hypertension in the overweight was 3.3 and in the obese 3.9, with a clustering of cardiovascular risk factors in the obese Chinese children of whom 90.5% had evidence of abdominal obesity. Even the overweight group had 15.8% with abdominal obesity. Based on the population attributable risks of overweight and obesity in 2002 and data on the direct medical costs of hypertension, diabetes, stroke and coronary heart disease, 25% of these comorbidity costs could be attributed to overweight and obesity. As the improvement in linear growth of young children is usually slower than their improvements in weight during the economic development of China, the long-term adult implications of having a problem of ‘Stunted obesity’ rather than simple obesity in young children are raised. Analysis of the associations between adult obesity with the individuals' fetal and early nutrition highlights the need for further investigation.