Trend in gender disparities of BMI and height between 2004 and 2011 among adolescents aged 17-18 years in Changzhou China

Objectives: to describe the trend in gender disparities of overweight/obesity and underweight, as well as height, among Chinese adolescents. Methods: the study is based on population-based data from annual health checks of approximately 7,000 students finishing high school each year between 2004-2011. Height and weight were measured. Overweight/obesity and underweight were defined using International Obesity Task Force (IOTF) criteria. School level socioeconomic status (SES) was constructed based on real-estate prices near each school. Results: there was a slight increase in the prevalence of obesity between 2004 and 2011; 3.7% to 4.7% in boys and 1.1% to 1.5% in girls. The prevalence of overweight was quite stable in both genders (boys: 12%-15%; girls: 7%-10%). In most years, the prevalence of underweight was above 10%. The prevalence of underweight in girls born after 1991 increased dramatically. However, the opposite trend was seen in boys. School SES was positively associated with overweight and inversely associated with underweight among boys. There was a significant increase in height in both genders. Height and BMI was positively associated in boys but this relation was inversely associated in girls. Conclusion: between 2004 and 2011, the prevalence of overweight/obesity was plateauing among adolescents finishing high school. A substantial increase in the prevalence of underweight was observed among girls born after 1991 but this seemed to be positively associated with high SES.