Preventing childhood obesity primary schools: a realist review from UK perspective

Objective to identify contextual and mechanistic factors associated with outcomes of school-based obesity prevention interventions which may be implementable in UK primary schools. Design realist synthesis following REMESES guidance. We developed an initial programme theory through expert consensus and stakeholder input and refined it with data from included studies to produce a final programme theory including all context-mechanism-outcome configurations. Setting primary schools Participants children aged 4-12 Interventions included in the 2019 Cochrane review on prevention of childhood obesity Outcomes BMIz Results We included 24 studies comprised of 71 documents in our synthesis. We found that contextual factors such as baseline BMIz affects intervention mechanisms variably, while girls, older children and those with higher parental education consistently benefitted more from school-based interventions. Key mechanisms associated with beneficial effect were sufficient intervention dose, environmental modification, and the intervention components working together as a whole. Education alone did not produce favourable outcomes. Conclusions Interventions should go beyond education and incorporate a sufficient dose to trigger change in BMIz. Contextual factors deserve consideration when commissioning interventions to avoid widening health inequalities.