Associations between the “Double Reduction” policy and physical activity and overweight/obesity among Chinese school-aged children: a quasi-experimental difference-in-differences analysis

BackgroundIn July 2021, China implemented the “Double Reduction” policy to ease homework burden and curb off-campus tutoring for students in compulsory education. The policy has been evaluated mainly for academic and mental health outcomes; whether it coincided with changes in physical activity and weight status is unclear. This study used the policy as a natural experiment to examine associations between the Double Reduction policy, moderate-to-vigorous physical activity (MVPA), and overweight/obesity among Chinese school-aged children.MethodsWe analyzed the 2018, 2020, and 2022 waves of the China Family Panel Studies (CFPS) in a quasi-experimental difference-in-differences (DiD) design. At each wave, students enrolled in compulsory education (grades 1–9) formed the treatment group and senior high school students (grades 10–12), who were not covered by the policy, formed the comparison group. The analytical sample comprised 4,237 students contributing 10,799 person-wave observations. Outcomes were self-reported weekly MVPA minutes and overweight/obesity defined by age- and sex-specific body mass index z-scores (WHO 2007 reference). Event-study specifications, propensity-score weighting, longitudinal survey weights, and placebo tests assessed the stability of the estimates.ResultsThe policy was associated with 43.1 additional MVPA minutes per week (95% CI: 33.8–52.3; p < 0.001) and a 3.9 percentage-point reduction in overweight/obesity (95% CI: −7.2 to −0.6; p = 0.022) among compulsory education students relative to the comparison group. Estimates were larger among primary school students and among children whose parents had lower educational attainment. The 2018 pre-policy interaction was small and not statistically significant for either outcome, although two pre-policy waves offer limited power for testing pre-trends. Estimates were similar under balanced-panel, propensity-score-weighted, survey-weighted, and placebo specifications.ConclusionThe Double Reduction policy coincided with measurable improvements in physical activity and weight status among Chinese school-aged children. Education policies that relieve academic burden may carry collateral public health benefits and deserve explicit consideration in child health strategies.