Excessive gain in body mass index-for-age Z-score and associated factors: a cohort study in female adolescents.

Abstract

To evaluate the occurrence of excessive gain in body mass index-for-age Z-score (BMI/AZ) and its associated factors in adolescent girls. This is a cohort study conducted between 2007 and 2012 with 382 girls between 10 and 18 years of age attending public schools in Recife, Pernambuco, Brazil. Excessive gain in BMI/AZ (EGBMI/AZ) at follow-up was considered if the adolescent had a BMI/AZ >0.63 between follow-up and baseline. In 2007, 33.5% of girls were overweight, and at the end of the study this prevalence was 26.2%, with no statistically significant differences. Of the 382 girls evaluated in the cohort, 33% showed EGBMI/AZ. In 2007, 95% of these girls were normal weight or underweight, and in 2012, 60% were classified as overweight. After adjusting for possible confounding factors, three variables remained independently associated with EGBMI/AZ: underweight, normal weight and maternal overweight. Both underweight and normal weight were associated with EGBMI/AZ, and this could be due to a physiological protection for the occurrence of menarche. In fact, maternal overweight has considerable influence on adolescents' nutritional status because of exposure to an obesogenic environment.