title: The timing of solid introduction in an 'obesogenic' environment: a narrative review of the evidence and methodological issues.
abstract: OBJECTIVE
  To evaluate the evidence for association between obesity risk outcomes >12 months of age and timing of solid introduction in healthy term infants in developed countries, the large majority of whom are not exclusively breastfed to six months of age.
  
  
  METHODS
  Studies included were published 1990 to March 2013.
  
  
  RESULTS
  Twenty-six papers with weight status or obesity prevalence outcomes were identified. Studies were predominantly cohort design, most with important methodological limitations. Ten studies reported a positive association. Of these, only two were large, good-quality studies and both examined the outcome of early (<4 months) introduction of solids. None of the four good-quality studies that directly evaluated current guidelines provided evidence of any clinically relevant protective effect of solid introduction from 4-5 versus ≥6 months of age.
  
  
  CONCLUSIONS
  The introduction of solids prior to 4 months of age may result in increased risk of childhood obesity but there is little evidence of adverse weight status outcomes associated with introducing solids at 4-6 rather than at six months.
  
  
  CONCLUSIONS
  More and better quality evidence is required to inform guidelines on the 'when, what and how' of complementary feeding.
authors.affiliation: School of Exercise and Nutrition Sciences and Institute of Health and Biomedical Innovation, Queensland University of Technology.
authors.forename: Lynne
authors.initials: L
authors.lastname: Daniels
authors.affiliation: School of Exercise and Nutrition Sciences and Institute of Health and Biomedical Innovation, Queensland University of Technology.
authors.forename: Kimberley M
authors.initials: KM
authors.lastname: Mallan
authors.affiliation: School of Exercise and Nutrition Sciences and Institute of Health and Biomedical Innovation, Queensland University of Technology.|Health Behaviour Research Centre, Department of Epidemiology and Public Health, University College London, United Kingdom.
authors.forename: Alison
authors.initials: A
authors.lastname: Fildes
authors.affiliation: School of Exercise and Nutrition Sciences and Institute of Health and Biomedical Innovation, Queensland University of Technology.
authors.forename: Jacinda
authors.initials: J
authors.lastname: Wilson
mesh_terms: D001942:Breast Feeding; D002657:Child Development; D005260:Female; D006128:Growth; D006801:Humans; D007223:Infant; D007225:Infant Food; D007227:Infant Nutritional Physiological Phenomena; D008297:Male; D063766:Pediatric Obesity / Q000517:prevention & control*; D013997:Time Factors; D014886:Weaning
keywords: complementary feeding; developed countries; narrative review; obesity