Evaluation of the impact of a 12-week group therapy programme for the treatment of bulimia nervosa

Abstract

Introduction: Cognitive behavioural therapy (CBT) is widely recommended as the treatment for bulimia nervosa. CBT addresses dysfunctional cognitions pertaining to body image which are postulated to maintain disordered eating behaviours. CBT aims to reduce the frequency of binge eating and compensatory behaviours through promoting a reduction in dietary restriction and the adoption of regular eating patterns. There is limited evidence investigating the impact of CBT on eating behaviours and dietary intake. With the non-binge dietary intake of bulimic individuals deemed inadequate, investigations pertaining to the impact of CBT, which aims to replace binge eating with regular eating, on dietary intake is of importance. There has been one study investigating the impact of CBT on the nutritional intake of bulimic individuals which reported an increased number of nutritional inadequacies following treatment. However, the participant sample investigated did not exclusively receive CBT, with a proportion assigned to an alternative treatment. Aim: The overall goal of this study was to evaluate the impact of the 12-week group CBT programme facilitated by Tupu Ora Eating Disorder Services on individuals with bulimia nervosa. The primary aim was to investigate the impact that group CBT has on the intake of meals and snacks, specifically aiming to assess changes in the proportion of individuals adopting a regular eating pattern of 3 meals and 3 snacks daily by the close of treatment. The impact of CBT on binge eating and compensatory frequencies, nutritional intake, psychopathology, and body weight were also investigated. Method: Eight individuals with bulimia nervosa were provided with 7-day food diaries at the start and close of treatment for recording their dietary intake and detailing their intake as a meal or snack. Food diaries were analysed using FoodWorks 10 Professional and average daily nutrient intakes were compared with nutrient reference values to assess nutritional adequacy. Binge eating and compensatory frequencies were collected by self-recall, food diaries and via the Eating Disorder Examination Questionnaire (EDE-Q) at the start and close of treatment. Eating disorder related psychopathology was assessed using the EDE-Q and Depression Anxiety Stress Scale (DASS) which were also provided at the start and close of treatment. Body weight measures were also collected at these two timepoints. Findings: Meals and snacks could not be distinguished from one another due to a lack of and inconsistent recordings within food diaries. No participants achieved 6 eating episodes per day (reflecting the primary outcome criteria of 3 meals and 3 snacks) at the close of treatment. However, significant increases in the number of eating episodes and reductions in binge eating frequencies were achieved. There was disagreement between differing methods of data collection pertaining to changes in the frequency of compensatory behaviours, with weekly measures indicating no improvements and monthly measures indicating reductions in such behaviours. The daily non-binge intake of bulimic individuals significantly increased in energy, fat, and protein (the latter achieved borderline significance) by the close of treatment, with no change in carbohydrate intake. The contribution of energy from fats and carbohydrates was imbalanced relative to the acceptable macronutrient distribution, with the former exceeding recommendations and the latter below recommendations. The average daily non-binge micronutrient intake for the majority of participants achieved estimated average requirements at the close of treatment, with some potential inadequacies in calcium, iodine, selenium, zinc, and magnesium. Despite a decreasing trend, no significant changes were found in the total daily intake (binge intake combined with non-binge intake) of participants by the close of treatment. Significant improvements were found in measures of dietary restraint and eating concern as per the EDE-Q, with no change in concern with body shape, though improvements in concern with body weight were significant at the 10% level. Reductions in measures of stress were found at the close of treatment, with no significant change in measures of depression and anxiety. No significant change was found in body weight. Conclusion: Group CBT may offer a promising first line treatment for BN. However, a proportion of participants may benefit from additional individualised treatment.