Introduction: Obesity prevalence among children and adolescents has risen sharply, yet there is a limited understanding of the age-specific dynamics of obesity as there is no single nationally representative cohort following children into young adulthood. Investigators constructed a pooled data set of 5 nationally representative panels and modeled age-specific obesity incidence from childhood into young adulthood. Methods: This longitudinal prospective follow-up used 718,560 person-years of observation in a pooled data set of 5 high-quality nationally representative panels—National Longitudinal Survey of Youth 1979 and 1997, National Longitudinal Study of Adolescent Health, and Early Childhood Longitudinal Study-Kindergarten cohorts of 1998 and 2011—constructed by the authors, covering 1980–2016. Differences in obesity incidence across birth cohorts and disparities in obesity incidence by sex and race/ethnicity (non-Hispanic Black, Hispanic, and non-Hispanic White) were tested in multivariate models. Data were analyzed from September 2018 to October 2021. Results: Obesity incidence increased by approximately 6% for each 1 year of age (hazard ratio=1.06, 95% CI=1.05, 1.07); however, incidence was nonlinear, exhibiting an inverted “U”-shaped pattern before 15 years of age and then rising from adolescence through 30 years. Obesity incidence more than doubled between the cohorts born in 1957–1965 and those born in 1974–1985 during adolescence. There was no significant change among those born in 1991–1994 and 2003–2006 up to age 15 years. Compared with non-Hispanic White children, non-Hispanic Black and Hispanic children had higher obesity incidence in all study cohorts. The magnitude of these disparities on the relative scale remained stable throughout the study period. Conclusions: Although many children become obese before the age of 10, obesity incidence rises from about 15 years into early adulthood, suggesting that interventions are required at multiple developmental stages.

Changes in food choice often accompany globalization and economic growth. These changes have not been well documented in rural settings and among young people. To advance research on food choice, we demonstrate adolescents’ selection of local vs.non-local foods in a rural area of India where globalization is just reaching. A representative sample of 237 school-going adolescents in a village in Southern India completed a survey in 2019 to understand how adolescents decide among foods traditional to the area and foods arriving from other parts of the country and the world. Adolescents most frequently consumed local foods but also occasionally consumed non-local items. In hypothetical scenarios, 81% of the adolescents reported being most interested in substituting local foods with non-local foods if they were to have more money. Among the few who currently consumed non-local snacks and drinks, very few would be willing to replace them with local alternatives, particularly if they were to have more money (snacks: 10% and drinks: 5% respectively). Overall, adolescents were most interested in switching to non-local items when considering fruits, vegetables and snacks. As India faces the dual burden of undernutrition and overnutrition, understanding the changing food environment may help inform efforts to improve nutrition.