Description of survey and study population

The World Health Organization Health Behaviour in School‐Aged Children Study (HBSC) is a cross‐sectional survey administered every 4 years to youth from 44 countries across Europe and North America ¹⁴. The results herein are based on the Canadian responses from the 2013/2014 HBSC cycle. The purpose of the HBSC is to collect data on health indicators among youth for the purpose of policy development and health research ¹⁴. The survey consists of an anonymous questionnaire completed by students in the classroom setting. All of the WT, mental health and covariate data used in the present study were obtained from this questionnaire. The Canadian HBSC followed the international HBSC protocol and used a cluster sampling approach with school class as the primary sampling unit ¹⁵. The sample was designed to reflect the distribution of students in Grades 6–10 (approximately 11–15 years of age) across Canada according to school size, location, language and religion ¹⁵. The total sample included 30 107 youth. Youth with missing or invalid responses for WT (N = 759), psychosomatic symptoms (N = 2 488), height or weight (N = 7 144) or other covariates (N = 3 117) were excluded from the current analysis. Thus, data were analyzed on a final sample of 20,277 youth. Consent was obtained and provided by school boards, individual schools, participants and their parents or guardians. Ethics approval was obtained from the Queen's University General Research Ethics Board.