Background: An increase in self-harm emergencies after bariatric surgery have been documented, but understanding of the phenomenon is missing. Case presentation: The following case report describes a 26-year-old woman with obesity, who initiated self-harm behaviour after bariatric surgery. The patient reported that the self-harm was a substitute for binge eating, which was anatomically impeded after bariatric surgery. Pre-surgical psychosocial assessment revealed Anorexia Nervosa in youth, which had later migrated to Binge Eating Disorder. At the time of surgery, the patient was not fulfilling the diagnostic criteria for Binge Eating Disorder because of a low frequency of binges. The remaining binges occurred when experiencing negative affect. Conclusions: Previous eating disorder pathology is an important consideration in pre-surgical assessments. For patients with affect-driven pre-surgical Binge Eating Disorder, therapeutic intervention before and after bariatric surgery could be indicated in order to secure the development of adaptive coping strategies. Furthermore, body weight as the only outcome measure for the success of surgery seems insufficient.