title: Environmental factors associated with disordered weight-control behaviours among youth: a systematic review.
abstract: OBJECTIVE
  Environmental factors may be very important in the development of disordered weight-control behaviours (DWCB) among youth, yet no study to date has conducted a review that synthesizes these findings. The purpose of the present study was to systematically review existing literature on environmental influences on DWCB among youth and to identify conceptual and methodological gaps in the literature.
  
  
  METHODS
  Systematic review.
  
  
  METHODS
  Studies were identified through a systematic search using PubMed, PsycINFO, Google Scholar and secondary references. Inclusion criteria included observational studies published in peer-reviewed journals from 1994 to 2012 that examined environmental exposure(s) associated with DWCB among youth.
  
  
  METHODS
  Ninety-three studies, the majority of which utilized a cross-sectional design (75 %; n 70), were identified. Longitudinal studies' follow-up time ranged from 8 months to 10 years.
  
  
  RESULTS
  Parental, peer and media influences have been extensively studied as factors associated with DWCB among youth. Fewer studies have examined behavioural settings (i.e. homes, schools, neighbourhoods) or sectors of influence other than the media on DWCB. No studies utilized multilevel methods to parse out environmental influences on DWCB. Most studies (69 %, n 64) did not explicitly utilize a theory or model to guide the research.
  
  
  CONCLUSIONS
  Findings indicate that exploring a wider range of environmental influences on DWCB, specifically behavioural settings and sectors of influence, using diverse study samples and multilevel methodology is needed to advance the field and to inform the design of comprehensive prevention programmes that target DWCB and other weight-related behaviours.
authors.affiliation: 1Division of Preventive and Behavioral Medicine,University of Massachusetts Medical School,55 Lake Avenue North,S7-746,Worcester,MA 01605,USA.
authors.forename: Monica L
authors.initials: ML
authors.lastname: Wang
authors.affiliation: 3Human Nutrition Program,Department of Environmental Health Sciences,University of Michigan School of Public Health,Ann Arbor,MI,USA.
authors.forename: Karen E
authors.initials: KE
authors.lastname: Peterson
authors.affiliation: 2Department of Society,Human Development and Health,Harvard School of Public Health,Boston,MA,USA.
authors.forename: Marie C
authors.initials: MC
authors.lastname: McCormick
authors.affiliation: 2Department of Society,Human Development and Health,Harvard School of Public Health,Boston,MA,USA.
authors.forename: S Bryn
authors.initials: SB
authors.lastname: Austin
mesh_terms: D000293:Adolescent; D000294:Adolescent Behavior; D001068:Feeding and Eating Disorders / Q000517:prevention & control*; D006801:Humans; D009765:Obesity / Q000523:psychology*; D012111:Residence Characteristics; D012574:Schools; D012931:Social Environment