Premorbid Weight Status Predicts Weight Gain During Treatment of Adolescents with Anorexia Nervosa and Atypical Anorexia Nervosa.

Weight gain is instrumental in recovery from anorexia nervosa (AN)/atypical AN, yet the effect of premorbid weight status on treatment-related weight gain is unclear. In 71 medically hospitalized adolescents with AN/atypical AN, relative weight gain, measured via change in BMI z-scores, was assessed over 12-months of outpatient treatment following hospitalization and compared for premorbid weight status. Patients with premorbid overweight/obesity had a longer illness duration (p = .03) and more weight loss (p < .001) than patients with premorbid normal weight, and less weight gain at 3-, 6-, 9-, and 12-months post-discharge (all p's ≤ .01). Premorbid weight status was not associated with treatment dropout, medical readmissions, psychiatric hospitalizations, or psychotropic medication use (all p's > .05). Findings tentatively suggest that inpatients with AN/atypical AN and premorbid overweight/obesity gain less weight in the 12-months post hospitalization, despite similar illness severity indicators. Rigorous prospective studies are needed to solidify factors underlying these trends.