Introduction: Obesity is a constantly rising and cost-intensive medical issue worldwide. Severe obesity often needs surgery to promote weight loss, but due to the rapid therapeutic success after the surgery, many patients lack the awareness of the need to consistently maintain the postoperative care. However, therapeutic success and psychological well-being can be increased through group interventions and social support of the group members. Therefore, aftercare via group intervention is a promising approach. In this prospective randomised controlled study, the self-efficacy in a social media-based interactive, psychoeducational intervention is to be tested.

Methods and analysis: The intervention group will complete a social media-supported group intervention for 6 weeks with weekly postings of educative contents and the possibility to exchange in groups via anonymous avatars. The control group will receive treatment as usual (TAU) after the obesity surgery as recommended in the German S3-guidelines Obesity Surgery and Metabolic Surgery. We will examine the effectiveness of a social media-supported intervention group, and therefore, the change in self-efficacy expectation. For the primary outcome, we will perform a mixed analysis of variance with time as the within-subject factor (times of measurement T0–T4) and the group assignment as the between-subject factor (intervention +TAU vs TAU group).

Ethics and dissemination: The study was approved by the Medical Association North Rhine (Ärztekammer Nordrhein, 2020031) and the patient enrolment will begin in July 2021.