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. Conclusion: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. Implications:More and better quality evidence is required to inform guidelines on the ‘when, what and how’ of complementary feeding.