Objectives: The objectives of this study were to determine: 1) factors associated with body mass index (BMI) in women with bulimia nervosa prior to treatment; 2) changes in BMI during cognitive behavioral therapy (CBT) for bulimia nervosa; and 3) predictors of weight change during CBT treatment.
Methods: Participants were 94 women with DSM-III-R bulimia nervosa enrolled in a randomized clinical trial of CBT. Eating disorder symptomatology, past and current psychopathology, and BMI were measured prior to treatment and after twelve weeks of treatment.
Results: A significantly lower BMI prior to treatment was independently associated with a history of anorexia nervosa, substance use, cigarette smoking, and a high frequency of vomiting. Reductions in binge eating, purging, and food restriction after treatment did not result in significant changes in BMI. Increasing age, higher maximum lifetime body weight, and a high frequency of binge eating at baseline predicted weight gain during treatment. Weight loss during treatment was predicted by a high frequency of vomiting, and elevated levels of body dissatisfaction prior to treatment.
Discussion: Patients hesitant to engage in treatment for fear of weight gain upon cessation of their bulimic behaviors should be reassured that CBT is not usually accompanied by substantial weight gain. Identification of women at risk of significant weight gain or loss during CBT may enable therapists to focus on its aspects that help to prevent excessive body weight changes.