A longitudinal study on the change of eating disorder-specific and nonspecific habits during weight rehabilitation in anorexia nervosa.

Background: Patients with Anorexia Nervosa (AN) are characterized by rigid behavioral patterns and habit-like routines, especially regarding food intake. It has been hypothesized that habits contribute to the maintenance of AN-related symptoms. Therefore, it is crucial to understand the role of disorder-specific and nonspecific habits during weight-restoration treatment. Method: In this longitudinal study, we examined the frequency of habits using ecological momentary assessment in 44 adolescent patients with AN who were undergoing inpatient nutritional rehabilitation. All patients had two data collection periods: baseline at admission, and follow-up shortly before discharge from treatment. An age-matched healthy control group was included to assess normalization at follow-up. Results: Analyses revealed a significant decrease in food-intake and hygiene-related habit frequency from baseline to follow-up. Furthermore, at follow-up habit frequency of both categories no longer differed between AN and controls. Moreover, the degree of reduction of food intake habits was predictive of weight gain at follow-up. Conclusion: These findings may suggest that habitual behaviors are state factors, mainly present during the acute phase of the disorder, which advances our understanding of the habit hypothesis in AN. Changing such behaviors may be important for weight restoration, highlighting the potential value of interventions targeting habits.