The purpose of the study is to determine the effect of three weight loss procedures that differ on their manipulation of the anatomical and functional characteristics of the gastrointestinal tract. While in the conventional treatment the gastrointestinal system remains intact, in the SG only the stomach is manipulated as opposed to the RYGB, where both the stomach and the small intestine are operated on. Since bariatric surgery is well known to induce partial or total remission of type 2 diabetes mellitus, the effects of the three different weight loss procedures will be assessed separately in obese normoglycemic and obese type 2 diabetic individuals.