the lifespan (from 12 years to 31 years old). For example, Adalbjarnardottir and Hafsteinsson (2001) followed youth for only 4 years during adolescence (ages 14 to 18 years). Examining the etiology of HED trajectories into young adulthood is particularly important because the emerging adulthood period (18 to 25 years old) has been identified as one of the most vulnerable periods for HED (Tucker, Ellickson, Orlando, Martino, & Klein, 2005). Given this critical period of development, more research is needed that examines the lasting effects of the adolescent years on health behavior throughout development and changes in such behaviors over time.
