title: Effects of a 20-month cluster randomised controlled school-based intervention trial on BMI of school-aged boys and girls: the HEIA study.
abstract: BACKGROUND
  School-based interventions that target prevention of overweight and obesity in children have been tested with mixed results. Thus, successful interventions are still called for. The aim of the present study was to investigate effects of a multicomponent school-based intervention programme targeting physical activity, sedentary and dietary behaviours on anthropometric outcomes.
  
  
  METHODS
  A 20-month intervention was evaluated in a cluster randomised, controlled study of 1324 11-year-olds. Outcome variables were body mass index (BMI), BMI-for-age z-score (BMIz), waist circumference (WC), waist-to-height ratio (WTHR) and weight status (International Obesity Task Force's cut-offs). Weight, height and WC were measured objectively; pubertal status was self-reported and parental education was self-reported by the parents. Intervention effects were determined by one-way analysis of covariance and logistic regression, after checking for clustering effects of school, and moderating effects of gender, pubertal status and parental education.
  
  
  RESULTS
  Beneficial effects were found for BMI (p=0.02) and BMIz (p=0.003) in girls, but not in boys. While a beneficial effect was found for BMI (p=0.03) in participants of parents reporting a high level of education, a negative effect was found for WTHR in participants with parents reporting a low level of education (p=0.003). There were no intervention effects for WC and weight status.
  
  
  CONCLUSIONS
  A multicomponent 20-month school-based intervention had a beneficial effect on BMI and BMIz in adolescent girls, but not in boys. Furthermore, children of higher educated parents seemed to benefit more from the intervention, and this needs attention in future interventions to avoid further increase in social inequalities in overweight and obesity.
authors.affiliation: Department of Sports Medicine, Norwegian School of Sport Sciences, , Oslo, Norway.
authors.forename: May
authors.initials: M
authors.lastname: Grydeland
authors.forename: Mona
authors.initials: M
authors.lastname: Bjelland
authors.forename: Sigmund Alfred
authors.initials: SA
authors.lastname: Anderssen
authors.forename: Knut-Inge
authors.initials: KI
authors.lastname: Klepp
authors.forename: Ingunn Holden
authors.initials: IH
authors.lastname: Bergh
authors.forename: Lene Frost
authors.initials: LF
authors.lastname: Andersen
authors.forename: Yngvar
authors.initials: Y
authors.lastname: Ommundsen
authors.forename: Nanna
authors.initials: N
authors.lastname: Lien
mesh_terms: D015992:Body Mass Index; D002648:Child; D016000:Cluster Analysis; D002149:Energy Intake; D005081:Exercise Therapy / Q000379:methods; D005260:Female; D006293:Health Promotion / Q000379:methods*; D006801:Humans; D008297:Male; D009765:Obesity / Q000178:diet therapy / Q000517:prevention & control*; D012572:School Health Services; D057185:Sedentary Behavior; D055105:Waist Circumference
keywords: Adolescents; Health promotion through physical activity; Interactions between food intake and physical activity/exercise