Purpose: Knowledge on the change process in the treatment of anorexia nervosa (AN) is an important starting point for the improvement of treatment, yet very little evidence exists. In an exploratory analysis, we aimed to investigate the interdependencies between higher-rank change process factors, BMI and AN-specific cognitions and behaviours over the course of inpatient treatment.
Methods: We included 176 female adult AN inpatients from three specialized centres. The temporal interdependencies between the change factors and the outcome variables over the course of treatment (t0: beginning, t1: mid-treatment, t2: end) were investigated using a path model.
Results: The sample had a mean age of 27.1 years (SD = 8.9 years) and a mean BMI at admission of 15.0 kg/m2 (SD = 1.6 kg/m2). A greater basic need satisfaction and a greater emotional involvement and commitment to treatment at t0 positively influenced the BMI at t1. Furthermore, greater basic need satisfaction at t0 led to less AN-specific cognitions and behaviours at t2.
Conclusions: The results are discussed with respect to the self-determination theory and the consistency theory. Further research on the change process in AN treatment is recommended.
Keywords: Anorexia nervosa; Basic need satisfaction; Change process; Inpatient treatment.