Trends in body mass index among Chinese children and adolescents aged 7–15, 2010–2022

Purpose To characterize trends in body mass index (BMI) and in overweight and obesity prevalence among Chinese children and adolescents aged 7–15 from 2010 to 2022, and to inform targeted weight-management strategies. Methods Data from 27,755 person-observations drawn from seven waves (2010–2022) of the China Family Panel Studies were stratified by sex and age. Overweight and obesity were classified using the sex- and age-specific BMI cut-offs of the Chinese Guidelines for Weight Management (2024 Edition). Mean BMI was summarized by descriptive statistics; trends were assessed with Spearman correlation between survey year and mean BMI, and prevalence differences were compared with chi-square tests; mean annual percentage-point changes between adjacent surveys were also computed. Results Body mass index (BMI) at ages 7–15 showed no significant overall linear trend ( P > 0.05), but increased with survey year among boys aged 10 and older (r_s = 0.082–0.189, P < 0.01) and girls aged 11 and older (r_s = 0.079–0.197, P < 0.001). Overweight prevalence rose markedly among boys aged 8 and 13–15 and 15-year-old girls ( P < 0.05), while obesity fell among the youngest boys and girls but rose among boys aged 12–13 and girls aged 13–15 ( P < 0.05); mean annual percentage-point changes peaked during 2016–2018 and were higher at ages 10–15 than at ages 7–9. Conclusions From 2010 to 2022 the prevalence of overweight and obesity diverged by age, improving among younger children but worsening among adolescents, particularly boys aged 10 and older and girls aged 12 and older. Intervention efforts should be brought forward to the upper elementary school years, be differentiated by sex and age, and prioritize weight management for adolescent boys. These trends are descriptive; the observational design precludes causal inference.