Identifying behaviour change techniques in school-based childhood obesity prevention interventions: a secondary analysis of a systematic review

Background: Childhood overweight and obesity is increasingly prevalent, can persist into adulthood, and lead to lifelong negative health trajectories. Schools are a recommended setting for childhood obesity prevention interventions; however, these interventions are often complex and multicomponent. While previous reviews have demonstrated their effectiveness, they have not identified which behaviour change techniques (BCTs – active ingredients of an intervention) are most effective. 

Objectives: Describe BCTs used in healthy eating (HE) and physical activity (PA) intervention components of obesity prevention interventions supporting children aged 6–18 years; and explore which BCTs are associated with child weight. 

Methods: A secondary analysis of school-based trials included in a 2022 update of a Cochrane systematic review was undertaken. The previous review included 195 randomised controlled trials of childhood obesity prevention interventions targeting HE and/or PA that assessed the body mass index of children aged 6–18 years. For this study, only trials delivered in schools that compared an intervention to a non-intervention control group and targeted HE, PA or both were eligible. Individual BCTs of each HE and PA intervention were coded according to the BCT taxonomy v1. Meta-regressions were conducted to determine the association between BCTs included in the trials and child weight. 

Results: This secondary analysis included 124 eligible trials. Fifty-five of the 93 BCTs from 14 of the 16 BCT domains were identified across interventions. Interventions with a HE component that included BCTs from three domains (Goals and planning; Social support; Comparison of behaviour) were found to have a significant association with a positive effect on child weight, whereas there were no significant associations found for interventions with a PA component. 

Conclusion: School-based obesity prevention interventions with HE components that included BCTs within the Goals and planning, Social support, and Comparison of behaviour domains, such as Goal setting (outcome), Social support (unspecified) and Demonstration of the behaviour were associated with a positive effect on child weight and should be considered for prioritisation in future interventions. Further research is required to identify effective BCTs for PA intervention components, and for effective individual BCTs and combinations of BCTs for all obesity prevention interventions broadly. 

Trial registration: CRD42022366743.