Requires a shift in social norms, not just an exercise programme

Despite heightened interest in preventing obesity in childhood, the evidence base for the effectiveness of local school based programmes and changes in policy to combat childhood obesity is poor.1 2 3 Even less research has been devoted to improving nutrition and physical activity in preschool and childcare settings, where further challenges exist, such as lack of uniformity between programmes and fragmented oversights by regulatory authorities.1 3 Yet increasing evidence shows that preschool practices can influence the overall energy expenditure of young children.4 ^w1

In this issue of the BMJ, Reilly and colleagues address this gap in the literature with a rigorously designed, cluster randomised controlled trial of an intervention to promote physical activity in 36 Scottish nursery schools.5 Body mass index and physical activity were not …