Spillover effects of childhood obesity prevention interventions: A systematic review

Summary Background Childhood obesity prevention initiatives are complex interventions that aim to improve children's obesity‐related behaviors and provide health promoting environments. These interventions often impact individuals, communities, and outcomes not primarily targeted by the intervention or policy. To accurately capture the effectiveness and cost‐effectiveness of childhood obesity prevention interventions, an understanding of the broader impacts (or spillover effects) is required. This systematic review aims to assess the spillover effects of childhood obesity prevention interventions. Methods Six academic databases and two trial registries were searched (2007–2023) to identify studies reporting quantifiable obesity‐related and other outcomes in individuals or communities not primarily targeted by an obesity prevention intervention. Critical appraisal was undertaken for studies that reported statistically significant findings, and a narrative synthesis of the data was undertaken. Results Twenty academic studies and 41 trial records were included in the synthesis. The most commonly reported spillovers were diet or nutrition‐related, followed by BMI and physical activity/sedentary behavior. Spillovers were mostly reported in parents/caregivers followed by other family members. Nine of the 20 academic studies reported statistically significant spillover effects. Conclusion Limited evidence indicates that positive spillover effects of childhood obesity prevention interventions can be observed in parents/caregivers and families of targeted participants.