Overweight dynamics in Chinese children and adults.

China has experienced a transition from a history of undernutrition to a rapid increase in obesity. The China Health and Nutrition Survey, an ongoing longitudinal, household-based survey of urban and rural residents of nine provinces, documents these changes using measured height and weight across 53,298 observations from 18,059 participants collected from 1991 to 2011. Adult overweight (body mass index [BMI] ≥ 25 kg/m(2)) prevalence nearly tripled from 1991 (11.7%) to 2009 (29.2%), with significant cohort and age-related effects (stronger in males). Among youth, quantile regression reveals changes across the BMI distribution. By 2009, approximately 12% of children and adolescents were overweight, and 3% of 7-11-year-olds and 1% of 12-17-year-olds were obese (International Obesity Taskforce BMI 25 and 30 kg/m(2) equivalents, respectively). In 1991-2000, urbanicity was strongly and positively associated with BMI, but in 2000-2011, trends were similar across rural and urban areas. Among women, the burden has shifted to lower educated women (the reverse is true for males, as overweight was higher in men of higher education). Our findings highlight the importance of preventive measures early in the life cycle to reduce weight gain.