LAUSR

PURPOSE While high levels of obesity prevalence and incidence have been well documented, there is less research on obesity dynamics over time. In this article, we sought to understand the body mass index (BMI) trajectories in and out of obesity from adolescence to adulthood. METHODS We used the National Longitudinal Study of Adolescent to Adult Health to explore American obesity dynamics from mean ages 15-28 years. We analyzed six BMI trajectories from 1994 to 2008 and examined their contextual sociodemographic correlates using ordinal logistic regression models. RESULTS More than 50% of adolescents with normal BMI moved to overweight/obesity by adulthood; only 8% of overweight and 2% of obese adolescents achieved normal BMI in adulthood. While some sociodemographic characteristics such as sex, race/ethnicity, place of residence, and parents' education were associated with being in certain BMI trajectories among adolescents with normal BMI, they were not so associated among adolescents starting at obesity. CONCLUSIONS Transitioning to higher BMI categories was common, whereas the opposite direction was rare. Pathways to obesity prevention might be easier to identify than those to reversal, as contextual factors had more explanatory power for youths with normal BMI than for those with obese BMI.