Evaluation of a Web-Based Intervention for Bulimia Nervosa

This study evaluates the effectiveness of a web-based intervention specifically designed for patients with Bulimia Nervosa (BN) in a blinded randomized controlled trial.

After a sign-up process, a diagnostic interview, and a baseline assessment, eligible participants will be randomly allocated either to (1) an intervention group including the online web-based intervention for BN or (2) a waitlist control group with delayed access to the intervention (12 weeks). The program comprises six mandatory weekly sessions and six modular specialization areas resulting in a treatment period of 12 weeks. Minimal guidance is provided via a chat function.

Assessments will be conducted at pretreatment (study entrance), six weeks after baseline (mid-treatment), and 12 weeks after baseline (post-treatment).

The investigators expect that the intervention group will show lower frequencies of binge eating episodes and compensatory behavior as the primary outcome variables after the 12 weeks of treatment compared to a waitlist control condition. Moreoever, the investigators assume that there will be a higher reduction in global eating disorder symptoms, comorbid psychopathology, and a higher increase in well-being and self-esteem over 12 weeks in the intervention group compared to the waitlist control group.

Finally, the investigators expect that the intervention group will demonstrate a significantly higher reduction in functional impairment, substantially better restoration of work capacity, and an improved ability to regulate emotions after the 12 weeks of treatment.

Background: Bulimia Nervosa (BN) is characterized by persistent episodes of uncontrolled eating and inappropriate compensatory behaviors, associated with marked impairments in physical and mental health, social integration, professional performance, and overall quality of life. Although cognitive-behavioral therapies are effective for bulimia nervosa, access to specialized treatment in Germany is limited due to patient-related barriers and insufficient healthcare resources. Internet-based interventions can overcome this treatment gap and reduce the burden of BN for both patients and the healthcare system by making evidence-based interventions more accessible.

Goal: This study evaluates the effectiveness of a web-based intervention specifically designed for patients with BN in a blinded randomized controlled trial.

Method: After a sign-up process, a structured diagnostic interview, and a baseline assessment, eligible participants will be randomly allocated either to (1) an intervention group including the online web-based intervention for BN or (2) a waitlist control group with delayed access to the intervention (12 weeks). The program comprises six mandatory weekly sessions covering topics related to eating behaviors, emotion regulation, and stress management, followed by an optional set of up to six modular specialization areas based on individual therapy goals. Moreover, minimal guidance is included, consisting of technical support and answering questions via a chat function. Assessments will be conducted at pretreatment (study entrance), six weeks after baseline (mid-treatment), and 12 weeks after baseline (post-treatment). The primary outcome will be the number of binge eating episodes and compensatory behaviors. Secondary measures include global eating pathology, comorbid psychopathology, quality of life, self-esteem, emotion regulation, work capacity, and functional impairments.

Statistical Analyses: An intention-to-treat analysis will be performed to examine differences between the intervention and the control group in the change of eating disorder symptoms and secondary outcomes from pre- to post-treatment.

Hypotheses: The investigators expect that the intervention group will show lower frequencies of binge eating episodes and compensatory behavior as the primary outcome variables after the 12 weeks of treatment compared to a waitlist control condition. The investigators assume that there will be a higher reduction in global eating disorder symptoms, comorbid psychopathology, and a higher increase in well-being and self-esteem over 12 weeks in the intervention group compared to the waitlist control group. Moreover, the investigators expect that the intervention group will demonstrate a significantly higher reduction in functional impairment, substantially better restoration of work capacity, and an improved ability to regulate negative emotions after the 12 weeks of treatment.

Eligibility Criteria:
Inclusion criteria:

* sufficient German language skills (C1)
* permanent internet access during the study period
* meeting the diagnostic criteria for Bulimia Nervosa according to the Diagnostic and Statistical Manual of Mental Disorders (DSM-5)

Exclusion criteria:

* current severe depressive episode
* acute suicidality
* comorbid bipolar disorder or psychotic disorders
* acute substance dependence
* current psychotherapy or pharmacotherapy for eating disorders
* Body Mass Index (BMI) below 18.5