Background: Determining trends in the nutritional status of children may guide care prevention beyond this age in an effort to reduce the prevalence and incidence of overweight and/or obese children. The objective of this study is to evaluate the evolution of the nutritional status of preschool children in two moments, with an interval of 2 years. Methods: This is a cohort study of a random probabilistic sample of preschool children attending public schools within an urban area of high human development index city, in the hinterland of São Paulo state. In 2016, we reassessed the nutritional status of 351 preschoolers evaluated in 2014, comparing the prevalence of overweight according to BMI >1 z-score. Results: The prevalence of overweight was 31.05% (2014) and 31.06% (2016) and mean BMI z-scores were 0.58 and 0.57, respectively. The nutritional status classification of the preschool children showed almost no agreement between the two time points (κ = 0.053). Nevertheless, children with overweight in 2014 had a relative risk of 1.96 of being overweight or obese in 2016 (p = 0.0473). Conclusions: Prevalence of overweight among preschoolers was the same at 2 and 5 years of age, with no tendency to grow. Despite this, 2-year-old preschoolers with overweight present a twofold higher relative risk for excessive weight at 5 years of age. These changes of nutritional status at preschool age evince the great flexibility of their nutritional condition during this period of life.
Keywords: body mass index; childhood obesity; cohort studies; nutrition assessment; prevalence.