The Roux-en-Y Gastric ByPass, which is more complex, is an invasive procedure. In the upper part of the stomach, a small gastric pouch, partially similar to the tube stomach, is formed. And the rest of the stomach, which is about 90-95% of the stomach, is separated. By connecting this small stomach section to this small intestine, the gastrointestinal tract is changed.
The small intestine has a length of 600-1000 cm normally. The end where the gall comes to the intestine is joined to the end where the nutrition comes, approximately 1 meter further. The joining of gall with food towards the end of the small intestine mainly causes malabsorption (reduced absorption) of fats and starches. However, this also causes malabsorption of various minerals and fat-soluble vitamins at the same time. Unabsorbed fats and starches pass into the large intestine. Thus, the food directly goes down to the small intestine when the patient eats, and the decrease of the fat, sugar, and calorie absorption in the body, results in weight-loss.
However, it is possible to experience more serious problems (such as severe vitamin deficiency) with nutrition. On the other hand, the bacterial activity here may cause the production of irritants and malodorous gas formation.