Whole-body human physiology studies including lifestyle and therapeutic interventions combined with glucose clamps, oral and intravenous glucose challenges, meal tests and stable tracer methodology; pathophysiological investigations, and clinical proof-of-concept studies as well as clinical phase 2a, 2b, 3 and 4 studies in the fields of obesity and its related co-morbidities such as prediabetes, type 2 diabetes, non-alcoholic fatty liver disease, and bile acid malabsorption, but also type 1 diabetes, glucocorticoid-induced diabetes and other metabolic disorders. Studies involving skin, adipose tissue (subcutaneous and visceral), muscle, liver and brain biopsies as well as enteroscopic investigations involving mucosa biopsies from the entire length of the gastrointestinal tract. Evaluations of body composition and bone mineral density, gastrointestinal motility, brown adipose tissue activity (by thermal imaging).