A multi-level examination of the association between older social models in the school environment and overweight and obesity among younger students.

Few studies have examined how school characteristics are associated with obesity. The purpose of this study was to examine the student- and school-level characteristics associated with being overweight and obese among 12,049 students in grades 9 and 10 (junior students) attending 76 secondary schools in Ontario, Canada. The sample was 49.2% female and the average age was 14.7 years. Overall, 15.0% of the sample was considered overweight and 6.3% of the sample was considered obese. Multi-level regression analysis revealed significant between-school random variation for the likelihood of a junior student (grade 9 or 10) being overweight or obese. For each 1% increase in the prevalence of obese senior students (grade 11 and 12) at a school, the odds of a junior student at that school being overweight or obese increased significantly. Important student-level characteristics included physical activity, screen time sedentary behaviour (e.g., watching television), participation in varsity sports and gender. Future research should evaluate if the optimal population level impact for school-based obesity prevention programming might be achieved by targeting the schools that are putting students at the greatest risk.