Prevalence of overweight, obesity, and associated risk factors among school children and adolescents in Tianjin, China

To estimate the prevalence and determinants of overweight and obesity among school children and adolescents (7-18 years), a cross-sectional study was conducted in Tianjin City of Northeast China. Five primary and middle schools were selected using a multistage random cluster sampling. Anthropometric measurements were taken by the research team. Then, standardized questionnaires on socioeconomic status, diet and lifestyle, parental weight and height were sent to the parents to be completed together with their child. Overall, 3,140 students were screened for overweight and associated risk factors. Body mass index classification reference proposed by the Working Group on Obesity in China was used as a screening reference to calculate the prevalence of overweight in these groups. The prevalence of overweight and obesity was found to be 12.5% and 15.7%, respectively. Logistic regression analysis (overweight compared with normal weight) showed that, overweight in children was significantly associated with male gender, parental obesity, parental educational level, mother's history of gestational diabetes, high birth weight, less hours of physical activity per day, urban residence, motorized transportation, and eating food not prepared at home. After adjusting for parental obesity, the odds ratio of overweight children was increased by urban residence (rural as a reference, 2.68, 2.16-3.32), positive gestational diabetes (2.76, 1.37-4.50), and fast-food/ restaurant food service (2.03, 1.34-3.07). Children who walked to school and participated in outdoor activities were 54% and 63% less likely to be overweight respectively. Conclusions: The prevalence of overweight and obesity is high among school children and adolescents in Tianjin. Changes in lifestyle, high socioeconomic status, parental obesity, mother's history of gestational diabetes, and high birth weight are among the highly associated risk factors of overweight. An educational approach about maintaining a healthy weight should be introduced much earlier to high-risk children, parents, and women of childbearing age.