Does psychotherapy for binge eating remediate nutritional intake in people with bulimia nervosa and binge eating disorder?

Abstract

People who binge eat (those with bulimia nervosa (BN) and binge eating disorder (BED)) have a significantly disturbed nutritional intake compared to people who don’t binge eat. Moreover, people who binge eat consume excess energy, have altered macronutrient ratios, and have diets that are deficient in many vitamins and minerals. While the nutritional intakes of people who binge eat are well-researched, few studies contrast the nutritional intakes of people with BN and BED. Additionally, while cognitive behavioural therapy (CBT) is the most researched psychotherapy for binge eating-related disorders, little is known about the nutritional outcomes of this treatment. Appetite-focussed cognitive behavioural therapy (CBT-A) is an augmented version of CBT that provides modified nutritional advice and aims to improve response to cues of hunger and satiety. CBT-A has good treatment outcome, similar to that of traditional CBT, however whether there is a nutritional benefit attributable to the nutrition-related augmentations of CBT-A has not been investigated. A sample of 79 women with either BN (n = 38) or BED (n = 41) were randomised to CBT or schema therapy (n = 57), or to CBT-A (n = 22). Participants completed seven-day prospective food records pre-, mid-, and post-treatment and these records were entered into a nutritional software that provided average intakes of total energy, macronutrients and micronutrients. Nutrient intakes were compared to empirically-determined healthy intakes or ratios, and summary measures of macronutrient, micronutrient, and total adequacy were created. Nutritional intake and nutritional adequacy were modelled over time and between groups using linear mixed models analyses. Modelling nutritional variables suggested that psychotherapies for transdiagnostic binge eating reduced the energy, macronutrient, and mineral intakes over weekly sessions of treatment and many of these changes were maintained over monthly sessions. Vitamin intakes did not change despite reductions in food intake, and participants received less of their total energy from sugars, total fats, and saturated fats, and more from protein. These changes occurred alongside increased macronutrient adequacy over the first half of treatment and reduced micronutrient adequacy over the first half of treatment, which was maintained at the end of treatment. Little separated people with BN and BED nutritionally, and nutritional responses to treatment did not differ between diagnostic groups. Nutritional responses to the two treatment types were indistinguishable. Results support the use of transdiagnostic nutritional advice, however, fail to support the modified nutritional advice of CBT-A. The current study broadens knowledge about the nutritional outcomes of treatments for binge eating and these results likely have implications in understanding the high medical burden associated with BN and BED.