title: Linking childhood obesity to the built environment: a multi-level analysis of home and school neighbourhood factors associated with body mass index.
abstract: OBJECTIVE
  This study examines environmental factors associated with BMI (body mass index) levels among adolescents with the aim of identifying potential interventions for reducing childhood obesity.
  
  
  METHODS
  Students (n=1,048) aged 10-14 years at 28 schools in London, ON, completed a survey providing information on age, sex, height, weight, home address, etc., which was used to construct age-sex adjusted BMI z-scores. The presence of recreation opportunities, fast-food outlets and convenience stores was assessed using four areal units around each participant's home and school neighbourhood: "circular buffers" encompassing territory within a straight-line distance of 500 m and 1000 m; and "network buffers" of 500 m and 1000 m measured along the street network. School neighbourhoods were also assessed using school-specific "walksheds". Multilevel structural equation modeling techniques were employed to simultaneously test the effects of school-environment (Level 2) and home-environment (Level 1) predictors on BMI z-scores.
  
  
  RESULTS
  Most participants (71%) had a normal BMI, 16.9% were overweight, 7.6% were obese, and 4.6% were considered underweight. Multilevel analyses indicated that built environment characteristics around children's homes and schools had a modest but significant effect on their BMI. The presence of public recreation opportunities within a 500 m network distance of home was associated with lower BMI z-scores (p&lt;0.05), and fast-food outlets within the school walkshed was associated with higher BMI z-scores (p&lt;0.05).
  
  
  CONCLUSIONS
  Interventions and policies that improve children's access to publicly provided recreation opportunities near home and that mitigate the concentration of fast-food outlets close to schools may be key to promoting healthy lifestyles and reducing childhood obesity.
authors.affiliation: Human Environments Analysis Laboratory, Department of Geography, University of Western Ontario, London, ON. jgillila@uwo.ca
authors.forename: Jason A
authors.initials: JA
authors.lastname: Gilliland
authors.forename: Claudia Y
authors.initials: CY
authors.lastname: Rangel
authors.forename: Martin A
authors.initials: MA
authors.lastname: Healy
authors.forename: Patricia
authors.initials: P
authors.lastname: Tucker
authors.forename: Janet E
authors.initials: JE
authors.lastname: Loebach
authors.forename: Paul M
authors.initials: PM
authors.lastname: Hess
authors.forename: Meizi
authors.initials: M
authors.lastname: He
authors.forename: Jennifer D
authors.initials: JD
authors.lastname: Irwin
authors.forename: Piotr
authors.initials: P
authors.lastname: Wilk
mesh_terms: D000293:Adolescent; D015992:Body Mass Index; D002648:Child; D004779:Environment Design / Q000706:statistics & numerical data*; D057140:Fast Foods / Q000706:statistics & numerical data; D005260:Female; D006801:Humans; D008297:Male; D055361:Multilevel Analysis; D009765:Obesity / Q000453:epidemiology*; D009864:Ontario / Q000453:epidemiology; D011633:Public Facilities / Q000706:statistics & numerical data; D011998:Recreation; D012111:Residence Characteristics / Q000706:statistics & numerical data*; D012307:Risk Factors; D012574:Schools
keywords: adolescent; child; diet; environment; obesity; recreation