Trajectories of eating behaviors in a nationally representative cohort of US adolescents during the transition to young adulthood

Background: Diets of U.S. adolescents and adults do not meet recommendations, increasing risk of chronic disease. This study examined trajectories and predictors of eating behaviors in U.S. youth from age 16-20 years, and evaluated longitudinal associations of eating behaviors with weight outcomes. Methods: Data come from the first four waves (years) of the NEXT Generation Health Study, a nationally representative cohort of U.S. students in 10th grade during the 2009-2010 school year (n = 2785). Annual surveys queried frequency of food group intake (times/day of fruit and vegetables, whole grains, sugar-sweetened soda, sweet and salty snacks), and meal practices (days/week of breakfast, family meals, fast food, and television during meals). Body mass index (BMI, kg/m(2)) was calculated from self-reported height and weight. Adjusted generalized estimating equations and linear mixed models with multiple imputation for missing data estimated eating behavior trajectories overall and by baseline weight status (normal weight = 5 <= BMI%ile < 85, overweight = 85 <= BMI%ile < 95, obese = BMI%ile >= 95), accounting for the complex sampling design. Separate GEE models estimated longitudinal associations of food group frequencies with meal practices and of BMI with eating behaviors. Results: Eating behaviors tracked strongly from wave 1-4 (residual intraclass correlation = 41 % - 51 %). Across all baseline weight categories, frequency of food group intake and meal practices decreased over time, except for fast food, which remained stable. Fruit/vegetable intake frequency was associated positively with family meals (beta +/- SE = 0.33 +/- 0.05) and breakfast (0.18 +/- 0.03), and inversely with fast food (-0.31 +/- 0.04), while whole grain intake frequency was associated positively with family meals (0.07 +/- 0.02), television meals (0.02 +/- 0.009) and breakfast (0.04 +/- 0.01). Soda and snacks were positively associated with television meals (0.08 +/- 0.008 and 0.07 +/- 0.009, respectively) and fast food (0.24 +/- 0.02 and 0.20 +/- 0.03, respectively), while soda was inversely associated with breakfast frequency (-0.05 +/- 0.01). Time-varying BMI was unrelated to eating behaviors other than an inverse association with time-varying snacks (-0.33 +/- 0.12). Conclusions: Strong tracking over time supports the importance of early establishment of health-promoting eating behaviors in U.S. adolescents. Findings suggest meal practices may be important intervention targets. Lack of evidence for hypothesized associations of BMI and eating behaviors indicates the need for research confirming these findings using more precise measures of dietary intake.