The review question: The review sought to assess how effective strategies were in supporting the implementation of school-based policies and practices to address student diet, physical activity, excessive weight gain, tobacco or alcohol use. We also assessed if these strategies led to improvements in these student health behaviours or weight status, enhanced school staff attitudes or knowledge regarding implementation, had any adverse effects, and were cost-effective.

Background: Research has identified a range of school-based policies and practices that may be potentially effective in improving student health behaviours. Despite this, such policies and practices are often not implemented in schools, even in circumstances where it is mandatory to do so. Unless evidence-based policies and practices are implemented, they can not benefit public health.

Study characteristics: We included 27 trials, 18 of which were conducted in the USA. Fifeteen trials tested strategies to implement healthy eating policies, practice or programs; six trials tested strategies targeting physical activity policies or practices; and three trials targeted tobacco policies or practices. Three trials targeted a combination of health behaviours. None of the included trials sought to increase the implementation of interventions to delay initiation or reduce the consumption of alcohol. The trials tested a range of implementation support strategies, including educational materials, educational meetings, the use of opinion leaders, external funding, local consensus processes, and tailored interventions.

Search date: The evidence is current to 31 August 2016.

Key results: It is uncertain whether the strategies tested improve implementation of the targeted school-based policies or practices, student health behaviours, or the knowledge or attitudes of school staff. It is also uncertain whether the strategies tested result in unintended adverse effects or whether they are cost-effective.

Limitations: Trial heterogeneity, and the lack of consistent terminology describing implementation strategies were important limitations of the review.

Quality of evidence: We rated the overall quality of evidence as very low for all outcomes that included trial-reported effects.