 Obesity and Type 2 Diabetes Mellitus are major health problems which are becoming a burden both for patients and health systems alike. The surgical and medical treatments available for these conditions have improved significantly in the last two decades. The investigators do not however know how these treatments compare to each other and how they act in the body to cause weight loss and diabetes improvements. The studies of this experiment are complementary to each other. They aim to answer related questions and will allow us to study how these treatments work and eventually develop safer and more effective therapies for obesity and diabetes. 