Disordered Eating Behaviors and 15-year Trajectories in Body Mass Index: Findings From Project Eating and Activity in Teens and Young Adults (EAT)

Purpose: Disordered eating behaviors are prevalent among adolescents. Understanding how these behaviors link to body mass index (BMI) across different stages of development and over an extended period may provide insight for designing interventions around eating and weight. This study had two objectives: (1) to assess the distribution of disordered eating behaviors and develop a global score of disordered eating behaviors among adolescents and (2) to examine the association between the number of disordered eating behaviors in adolescence and BMI trajectory over 15 years. Methods: Project Eating and Activity in Teens and Young Adults (EAT), a longitudinal study of weight-related health and behavior comprising four waves (EAT-I to EAT-IV), measured seven disordered eating behaviors (importance of weight and shape, frequent dieting, extreme unhealthy weight control behaviors, overeating, distress about overeating, loss of control while overeating, and frequency of overeating and loss of control) at baseline (N = 1,230, ages 11 to 18 years, 1998–1999). These behaviors were summed to create a disordered eating behavior score. BMI was self-reported at all four waves (up to age 27–33 years at EAT-IV). Repeated measures with random slope and intercept examined the association between disordered eating behaviors and BMI trajectories over 15 years. Results: At baseline, 50.7% and 33.7% of females and males endorsed disordered eating behaviors. Throughout 15 years of follow-up, sociodemographic-adjusted BMI was higher among adolescents who engaged in disordered eating behaviors. The association remained significant after further adjustment for baseline BMI (p < .05). Conclusions: Among adolescents, regardless of the type of disordered eating behaviors, engagement in disordered eating behavior predicted higher BMI in a dose-response fashion.