Time trend and demographic and geographic disparities in childhood obesity prevalence in China—evidence from twenty years of longitudinal data

Childhood overweight and obesity (ow/ob) has become a serious threat to many countries, including China. However, limited evidence was obtained from longitudinal data in China. This study examined the secular trends and geographic variation in the prevalence of ow/ob and obesity only, and age, gender, and urban-rural disparities among school-aged children across China. Data from children aged 6–17 surveyed in China Health and Nutrition Survey (CHNS) from 1991 (n = 2712) to 2011 (n = 1054) were used. Overweight and obesity were defined based on the International Obesity Task Force (IOTF) recommended Asian age-sex-specific BMI cut-off-points. We found that: (1) childhood ow/ob and obesity prevalence increased from 11.7% to 25.2% and from 2.8% to 10.1% during 1991–2011, respectively; (2) children aged 6–12 experienced a 1.3 and 1.6 times increase in ow/ob and obesity prevalence than children aged 13–17, respectively; (3) the urban-rural gap in ow/ob prevalence widened; (4) ow/ob prevalence in boys was higher and increased faster than in girls, especially in an urban setting; and (5) geographic variation was observed with faster increases in more economically developed east, central and northeast regions than in the less developed west. The findings added more nuances to the picture of temporal changes in ow/ob prevalence among Chinese children.