title: Mechanism by which BMI influences leisure-time physical activity behavior.
abstract: OBJECTIVE
  The objective of this prospective study was to clarify the mechanism by which BMI influences leisure-time physical activity. This was achieved in accordance with the assumptions underlying the Theory of Planned Behavior (TPB), considered as one of the most useful theories to predict behavior adoption.
  
  
  METHODS
  At baseline, a sample of 1,530 respondents completed a short questionnaire to measure intention and perceived behavioral control (PBC), the two proximal determinants of behavior of TPB. Past behavior, sociodemographic variables, and weight and height were also assessed. The dependent variable, leisure-time physical activity was assessed 3 months later.
  
  
  RESULTS
  Hierarchical multiple regression analyses revealed that BMI is a direct predictor of future leisure-time physical activity, not mediated by the variables of TPB. Additional hierarchical analyses indicated that BMI was not a moderator of the intention-behavior and PBC-behavior relationships.
  
  
  CONCLUSIONS
  The results of this study suggest that high BMI is a significant negative determinant of leisure-time physical activity. This observation reinforces the importance of preventing weight gain as a health promotion strategy for avoiding a sedentary lifestyle.
authors.affiliation: Faculty of Nursing, Laval University, Quebec City, Quebec, Canada. gaston.godin@fsi.ulaval.ca
authors.forename: Gaston
authors.initials: G
authors.lastname: Godin
authors.forename: Ariane
authors.initials: A
authors.lastname: Bélanger-Gravel
authors.forename: Bertrand
authors.initials: B
authors.lastname: Nolin
mesh_terms: D000328:Adult; D001519:Behavior / Q000502:physiology*; D015992:Body Mass Index; D005260:Female; D006306:Health Surveys; D006801:Humans; D007899:Leisure Activities / Q000523:psychology*; D008019:Life Style; D008297:Male; D008875:Middle Aged; D009043:Motor Activity / Q000502:physiology*; D009765:Obesity / Q000503:physiopathology / Q000517:prevention & control / Q000523:psychology; D011446:Prospective Studies; D012044:Regression Analysis