In the majority of patients with morbid obesity, metabolic/bariatric surgery leads to relevant and sustained weight loss and improves obesity-related comorbidities, quality of life and functionality. Moreover, the associated reduction of risk factors for cardiovascular events and cancerous diseases has been shown to improve life expectations. Due to its excellent antidiabetic effect, the currently valid national S3 guidelines now recommend metabolic/bariatric surgery in patients who have a body mass index (BMI) ≥30 kg/m with poorly controlled diabetes. The Edmonton staging system enables a multidimensional consideration of the severity grade of obesity for each individual patient independent of the BMI. Patients with relevant obesity-related metabolic comorbidities should be prioritized for treatment and if possible before the occurrence of end-organ damage that is at least in some cases irreversible and which also increases the perioperative risk. Therapeutic goals for each individual patient should be carefully defined preoperatively in order to mediate realistic expectations. Unrealistic expectations, such as "surgery solves my problems", "surgery makes me more beautiful", "surgery eliminates stigma", and "surgery guarantees success", are common in bariatric surgery patients. These unrealistic expectations can lead to frustration and to severe psychological decompensation and need to be addressed as early as possible by an interdisciplinary team. Redundancies, conclusive and empathic communication in the team improve therapy adherence, the expectations and therefore the overall outcome.