Lian Guo Fu1, Li Li Sun1, Shao Wei Wu2, Yi De Yang3, Xiao Hui Li3, Zheng He Wang3, Lu Wu1, Fu Zhi Wang1, Jun Ma3. 1. Department of Preventive Medicine, Bengbu Medical College, Bengbu 233030, Anhui, China. 2. Department of Environmental Health, Harvard T.H. Chan School of Public Health, Boston 02115, Massachusetts, USA. 3. Institute of Child and Adolescent Health, School of Public Health, Peking University Health Science Center, Bejing 100191, China.
Abstract
OBJECTIVE: To explore the influence of secular trends in body height and weight on the prevalence of overweight and obesity among Chinese children and adolescents. METHODS: The data were obtained from five cross-sectional Chinese National Surveys on Students' Constitution and Health. Overweight/obesity was defined as BMI-for-age Z-score of per the Wold Health Organization (WHO) reference values. Body height and weight for each sex and age were standardized to those reported in 1985 (standardized height: SHY; standardized weight: SWY) and for each sex and year at age 7 (standardized height: SHA; standardized weight: SWA) using the Z-score method. RESULTS: The prevalence of overweight/obesity in Chinese children was 20.2% among boys and 10.7% among girls in 2010 and increased continuously from 1985 to 2010. Among boys and girls of normal weight, SHY and SHA were significantly greater than SWY and SWA, respectively (P < 0.001). Among boys and girls with overweight/obesity, SHY was significantly lower than SWY (P < 0.001), and showed an obvious decreasing trend after age 12. SHA was lower than SWA among overweight boys aged 7-8 years and girls aged 7-9 years. SHY/SHW and SHA/SWA among normal-weight groups were greater than among overweight and obese groups (P < 0.001). CONCLUSION: The continuous increase in the prevalence of overweight/obesity among Chinese children may be related to a rapid increase in body weight before age 9 and lack of secular increase in body height after age 12.
OBJECTIVE: To explore the influence of secular trends in body height and weight on the prevalence of overweight and obesity among Chinese children and adolescents. METHODS: The data were obtained from five cross-sectional Chinese National Surveys on Students' Constitution and Health. Overweight/obesity was defined as BMI-for-age Z-score of per the Wold Health Organization (WHO) reference values. Body height and weight for each sex and age were standardized to those reported in 1985 (standardized height: SHY; standardized weight: SWY) and for each sex and year at age 7 (standardized height: SHA; standardized weight: SWA) using the Z-score method. RESULTS: The prevalence of overweight/obesity in Chinese children was 20.2% among boys and 10.7% among girls in 2010 and increased continuously from 1985 to 2010. Among boys and girls of normal weight, SHY and SHA were significantly greater than SWY and SWA, respectively (P < 0.001). Among boys and girls with overweight/obesity, SHY was significantly lower than SWY (P < 0.001), and showed an obvious decreasing trend after age 12. SHA was lower than SWA among overweight boys aged 7-8 years and girls aged 7-9 years. SHY/SHW and SHA/SWA among normal-weight groups were greater than among overweight and obese groups (P < 0.001). CONCLUSION: The continuous increase in the prevalence of overweight/obesity among Chinese children may be related to a rapid increase in body weight before age 9 and lack of secular increase in body height after age 12.