Key PointsQuestionIs there an association between circulating levels of the orexigenic hormone ghrelin and body weight trajectories in individuals with anorexia nervosa?FindingsIn this 18-month cohort study of 68 girls and young women, elevated baseline ghrelin levels were associated with prospective weight gain in anorexia nervosa.MeaningThis study offers evidence of association between ghrelin and longitudinal weight outcomes in individuals with anorexia nervosa; further studies are warranted to confirm this association and evaluate the potential clinical utility of ghrelin in anorexia nervosa.