Fostering self-endorsed motivation to change in patients with an eating disorder: the role of perceived autonomy support and psychological need satisfaction.

OBJECTIVE Although several studies have established the beneficial effects of self-endorsed forms of motivation for lasting therapeutic change, the way patients with an eating disorder can be encouraged to volitionally pursue change has received less attention. On the basis of Self-Determination Theory, this longitudinal study addressed the role of an autonomy-supportive environment and psychological need satisfaction in fostering self-endorsed motivation for change and subsequent weight gain. METHOD Female inpatients (n = 84) with mainly anorexia nervosa and bulimia nervosa filled out questionnaires at the onset of, during, and at the end of treatment regarding their perceived autonomy support from parents, staff members, and fellow patients, their psychological need satisfaction, and their reasons for undertaking change. Furthermore, the body mass index (BMI) of the patients at the onset and end of treatment was assessed by the staff. Path analyses were used to investigate the relations between these constructs. RESULTS At the start of treatment, perceived parental autonomy support related positively to self-endorsed motivation through psychological need satisfaction. Perceived staff and fellow patients autonomy support related to changes in self-endorsed motivation over the course of treatment through fostering change in psychological need satisfaction. Finally, relative increases in self-endorsed motivation related to relative increases in BMI throughout treatment in a subgroup of patients with anorexia nervosa. DISCUSSION These results point to the importance of an autonomy-supportive context for facilitating self-endorsed motivation.