King's College London

Purpose: Dysfunctional exercise is a common, debilitating symptom across eating disorders (ED). We examined the cross-sectional and longitudinal associations between experiences of exercise and ED behaviors and cognitions in an adolescent, population-based sample. Methods: Adolescents (n = 4,054) self-reported whether they exercised to control shape and weight (exercise for weight loss [EWL]), and, if so, whether they exercised even when injured, and whether exercise interfered with life functioning (driven exercise) at age 14 years, allowing delineation of three exercise-based groups: no-EWL, EWL, and driven exercise. Participants also reported ED cognitions at age 14 years along with other ED behaviors (fasting, purging, binge eating) at ages 14 and 16 years. Sex-stratified regression approaches were employed to examine relationships between these exercise categories at age 14 and ED behaviors and cognitions at ages 14 and 16. Results: Cross-sectionally, those in the driven exercise group, compared to the no-EWL group, consistently reported higher levels of ED cognitions and behaviors, with those in the EWL group also reporting higher levels of some ED cognitions and behaviors relative to the no-EWL group. Those in the EWL and driven exercise groups at age 14 also demonstrated a higher prospective likelihood of fasting (boys and girls) and purging (girls only) at age 16, relative to those in the no-EWL group at age 14. Discussion: Results inform our understanding of EWL and driven exercise and the developmental timing of ED behaviors in adolescence and point toward the potential utility of targeted prevention for young people who report EWL.