Evolution of nutritional status in a cohort of school age children Evolución del estado nutricional en una cohorte de escolares chilenos: ¿Un cambio real o ficticio?

Background: Considering the high prevalence of obesity among children attending elementary schools, it is important to know the evolution of body weight when these children reach adolescent. Aim: To analyze the changes in nutritional status of children between the first year of elementary school and the first year of high school. Material and methods: A historical cohort of children that were assessed when they started elementary school in 1997, was evaluated again eight years later. Weight and height were measured and body mass index (BMI) was calculated. Obesity was considered as a BMI over percentile 95 of Center for Disease Control (CDC) references. The concordance between nutritional assessment in both periods and the risk of obesity during adolescence, based on previous weight were also calculated. Results: Data from 117,815 children were analyzed. The prevalence of obesity in the first year of elementary school and the first year of high school was 14.6% and 7%, respectively. T