The choice of cutoffs for obesity and the effect of those values on risk factor estimation.

Several studies have examined risk factors for overweight and obesity. However, inconsistent results have been observed for estimations of some risk factors, such as the infant feeding method, and for their link to childhood obesity. These studies originated from different countries and used different body mass index cutoffs to define overweight and obesity. Using a theoretical approach and data obtained in preschoolers, we show that the identification of genuine risk factors for overweight or obesity does not depend on the choice of the reference system. However, for meaningful international comparisons, in particular for those of prevalence, studies should also report estimates by using a widely accepted international reference system.