title: The mediating effects of dietary habits on the relationship between television viewing and body mass index among youth.
abstract: OBJECTIVE
  There is evidence to suggest that excessive television viewing is an independent determinant of obesity in young people. However, the pathways between television viewing and obesity are not fully understood. Therefore, the purpose of this study was to examine whether the relationship between television and body mass index (BMI) is mediated by television snacking and junk food consumption.
  
  
  METHODS
  Results are based on 15,973 youth in grades 6-10 who participated in the Canadian 2009/2010 health behaviour in school-aged children survey (HBSC). Participants self-reported their weight and height and BMI z-scores were calculated based on World Health Organization growth standards. Participants reported the frequency of snacking while watching television and the frequency of eating junk food (sweets, soft drinks, baked goods, French fries, potato chips). Total hours per week of television were calculated. A contemporary multiple mediation analysis was used to examine associations.
  
  
  RESULTS
  A modest positive relationship was observed between television viewing and BMI. The mean BMI z-score was 0.15 units higher in youth in the highest television viewing quartile by comparison with the youth in the lowest quartile. However, contrary to our hypothesis, television snacking and junk food consumption were not significant positive mediators of the television and BMI relationship.
  
  
  CONCLUSIONS
  The pathways between television viewing and obesity are complicated and remain poorly understood. Future research using longitudinal or experimental designs, more precise measurement tools and formal mediation analyses is needed. This research should consider mediators related to both energy intake and expenditure.
authors.affiliation: School of Kinesiology and Health Studies, Queen's University, Kingston, ON, Canada.
authors.forename: Valerie
authors.initials: V
authors.lastname: Carson
authors.forename: Ian
authors.initials: I
authors.lastname: Janssen
mesh_terms: D000293:Adolescent; D015992:Body Mass Index; D002253:Carbonated Beverages; D002648:Child; D002149:Energy Intake; D004734:Energy Metabolism; D005247:Feeding Behavior; D005260:Female; D015438:Health Behavior; D006801:Humans; D008297:Male; D009765:Obesity / Q000453:epidemiology; D062410:Snacks; D013690:Television