title: A systematic review of controlled trials of interventions to prevent childhood obesity and overweight: a realistic synthesis of the evidence.
abstract: BACKGROUND
  Preventing childhood overweight and obesity has become a major public health issue in developed and developing countries. Systematic reviews of this topic have not provided practice-relevant guidance because of the generally low quality of research and the heterogeneity of reported effectiveness.
  
  
  OBJECTIVE
  To present practice-relevant guidance on interventions to reduce at least one measure of adiposity in child populations that do or do not contain overweight or obese children.
  
  
  METHODS
  Systematic review of eligible randomized, controlled trials or controlled trials using a novel approach to synthesizing the trial results through application of descriptive epidemiological and realistic evaluation concepts. Eligible trials involved at least 30 participants, lasted at least 12 weeks and involved non-clinical child populations.
  
  
  RESULTS
  Twenty-eight eligible trials were identified to 30 April 2006. Eleven trials were effective and 17 were ineffective in reducing adiposity. Blind to outcome, the main factor distinguishing effective from ineffective trials was the provision of moderate to vigorous aerobic physical activity in the former on a relatively 'compulsory' rather than 'voluntary' basis.
  
  
  CONCLUSIONS
  By using a novel approach to synthesizing trials, a decisive role for the 'compulsory' provision of aerobic physical activity has been demonstrated. Further research is required to identify how such activity can be sustained and transformed into a personally chosen behaviour by children and over the life course.
authors.affiliation: Institute of Health Sciences, The University of Reading, London Road, Reading RG1 5AG, UK. jbconn7@aol.com
authors.forename: J B
authors.initials: JB
authors.lastname: Connelly
authors.forename: M J
authors.initials: MJ
authors.lastname: Duaso
authors.forename: G
authors.initials: G
authors.lastname: Butler
mesh_terms: D050154:Adiposity; D000293:Adolescent; D002648:Child; D002675:Child, Preschool; D018849:Controlled Clinical Trials as Topic; D004032:Diet; D005260:Female; D006801:Humans; D008297:Male; D009043:Motor Activity; D009765:Obesity / Q000517:prevention & control; D050177:Overweight; D017410:Practice Guidelines as Topic; D016032:Randomized Controlled Trials as Topic