Childhood obesity: current definitions and recommendations for their use.

Childhood obesity is considered a major issue because of its high prevalence and because of its severe consequences on adult health. Prevalence studies are carried out in numerous countries. Analysis of time trends and geographic comparisons are particularly useful, as they may help to identify factors promoting obesity. These studies require adequate definitions of nutritional status and standardized protocols, but in practice, the references, cut-offs and the terminology used vary considerably, and consequently ambiguous information may be found in the literature. Recommendations for the definition of childhood obesity were previously published in 1995 by the European Childhood Obesity Group (ECOG), but new references appeared later. A clarification of the different definitions was needed. Currently used classifications of nutritional status in children are summarized, and recommendations for the references, cut-offs and terms to be used in different contexts are provided. These new ECOG recommendations should help harmonize the various protocols and improve comparisons between studies.