How Family and Individual Physical Activity Environments Relate to Obesity Transition in Chinese Children and Adolescents

<b>Background</b>: Overweight and obesity have emerged as major public health challenges in China, with rising prevalence rates posing substantial burdens on healthcare systems. This study is a secondary analysis of data from the 2019 Chinese National Survey on Students' Constitution and Health (CNSSCH), aimed to investigate the association of family and individual physical activity (PA) environments with overweight and obesity transition among children and adolescents, and to analyze subgroup differences by sex and urban-rural location as well as potential mechanisms. <b>Methods</b>: This was a one-year longitudinal study based on the 2019-2020 follow-up of 5008 children and adolescents. Family and individual physical activity environments were assessed as main exposures, and transitions to overweight and obesity were defined as outcomes. Multivariate logistic regression was applied to evaluate the association between family and individual PA environments and transitions to overweight and obesity, while also examining their moderating effects on unhealthy lifestyle behaviors. <b>Results</b>: A favorable family and individual PA environment was significantly associated with a reduced risk of obesity transition (OR = 0.78, <i>p</i> = 0.016). Subgroup analyses indicated that males (OR = 0.69, <i>p</i> = 0.009) and rural children and adolescents (OR = 0.70, <i>p</i> = 0.021) were more sensitive to supportive family and individual PA environments. Furthermore, a favorable environment was significantly correlated with a reduction in unhealthy behaviors such as skipping daily breakfast and consuming sugar-sweetened beverages (<i>p</i> < 0.001). <b>Conclusions</b>: A supportive family and individual PA environment was associated with a lower risk of obesity transition in children and adolescents, with more pronounced associations observed among males and those in rural areas.