title: The influence of market deregulation on fast food consumption and body mass index: a cross-national time series analysis.
abstract: OBJECTIVE
  To investigate the effect of fast food consumption on mean population body mass index (BMI) and explore the possible influence of market deregulation on fast food consumption and BMI.
  
  
  METHODS
  The within-country association between fast food consumption and BMI in 25 high-income member countries of the Organisation for Economic Co-operation and Development between 1999 and 2008 was explored through multivariate panel regression models, after adjustment for per capita gross domestic product, urbanization, trade openness, lifestyle indicators and other covariates. The possible mediating effect of annual per capita intake of soft drinks, animal fats and total calories on the association between fast food consumption and BMI was also analysed. Two-stage least squares regression models were conducted, using economic freedom as an instrumental variable, to study the causal effect of fast food consumption on BMI.
  
  
  RESULTS
  After adjustment for covariates, each 1-unit increase in annual fast food transactions per capita was associated with an increase of 0.033 kg/m2 in age-standardized BMI (95% confidence interval, CI: 0.013-0.052). Only the intake of soft drinks--not animal fat or total calories--mediated the observed association (β: 0.030; 95% CI: 0.010-0.050). Economic freedom was an independent predictor of fast food consumption (β: 0.27; 95% CI: 0.16-0.37). When economic freedom was used as an instrumental variable, the association between fast food and BMI weakened but remained significant (β: 0.023; 95% CI: 0.001-0.045).
  
  
  CONCLUSIONS
  Fast food consumption is an independent predictor of mean BMI in high-income countries. Market deregulation policies may contribute to the obesity epidemic by facilitating the spread of fast food.
authors.affiliation: Department of Public Health Sciences, School of Medicine, University of California Davis, One Shields Avenue, Med Sci 1-C, Davis, CA 95616, United States of America (USA).
authors.forename: Roberto
authors.initials: R
authors.lastname: De Vogli
authors.affiliation: School of Sociology, Social Policy and Social Work, Queen's University Belfast, Belfast, Northern Ireland .
authors.forename: Anne
authors.initials: A
authors.lastname: Kouvonen
authors.affiliation: Division of Epidemiology, Human Genetics and Environmental Health Sciences, The University of Texas Health Science Center at Houston, Houston, USA .
authors.forename: David
authors.initials: D
authors.lastname: Gimeno
mesh_terms: D015992:Body Mass Index; D019049:Developed Countries; D002149:Energy Intake; D057140:Fast Foods; D005247:Feeding Behavior; D005260:Female; D059066:Gross Domestic Product; D006801:Humans; D007182:Income / Q000706:statistics & numerical data; D008297:Male; D009765:Obesity / Q000453:epidemiology; D013996:Time and Motion Studies