The impact of school policies and practices on students' diets, physical activity levels and body weights: A province-wide practice-based evaluation.

OBJECTIVES: To assess what health promotion policies and practices were adopted by schools in Nova Scotia and the extent that these policies and practices affected the diet quality, physical activity (PA) and weight status of students.
METHODS: We developed and administered a 'school practice assessment tool' to assess the presence of 72 different school-based health promotion policies and practices. Surveys were conducted in 2003 and 2011 to assess diet, PA and weight status in approximately 10,000 grade 5 students. We used multilevel regression methods to examine changes in these outcomes across schools with varying levels of health promotion policies and practices between the two time-points.
RESULTS: Between 2003 and 2011 the diet quality of students improved, PA decreased and the prevalence of childhood obesity increased. Although we did not find consistent or significant favourable benefits resulting from higher implementation levels, we did observe fewer negative trends among schools at higher levels of implementation.
CONCLUSION: Our results build on the current gap in knowledge on the impact of Health Promoting Schools (HPS) implementation through population health interventions, but there is a continued need for further evaluation and monitoring of school policies to understand how HPS practices are supporting healthier eating and PA for students.