The effectiveness of school-based obesity prevention interventions on the health behaviours of children aged 6-18 years: A secondary data analysis of a systematic review.

Objectives: Obesity remains a contributor to the burden of disease globally. Suboptimal diet and physical inactivity are two rising risk factors of obesity in youth; both are targeted for obesity prevention. Further, these risk behaviours cluster and may be associated with other risks including smoking and alcohol intake. Few studies, however, have examined the extent to which interventions targeting obesity also impact on other health behaviours. The aim of this study is to synthesise the effects of child obesity prevention programs on diet, physical activity, tobacco smoking and alcohol intake, and to investigate differential effects by interventions that target different behaviours. Methods: A secondary data analysis of an existing systematic review was conducted. Literature searches identified any additional papers from 1990 to 2023 associated with the originally included studies. All papers were screened and were eligible if they reported any diet, physical activity, smoking or alcohol outcomes. Results for each health behaviour outcome were selected. Meta-analysis was conducted where possible to calculate standardised mean differences. Results: One hundred and four studies were eligible for inclusion. Fruit and vegetable intake (standardised mean difference (SMD) 0.104; 95 % (CI) (0.03, 0.17)), and sugar-sweetened beverage intake (SMD -0.126; 95 % CI (-0.22, -0.04)) were positively impacted by obesity prevention, as were physical activity (SMD 0.168; 95 % CI (0.05, 0.28)) and sedentary behaviour (SMD -0.021; 95 % CI (-0.03, -0.01)). Findings were mixed for tobacco smoking and alcohol intake. Conclusion: Independent of weight status, school obesity prevention programs may improve some measures of child dietary intake and physical activity. Study registration: Prospectively registered: PROSPERO: CRD42021281106.