While these operations also reduce the size of the stomach, the stomach pouch created is much larger than with other procedures. The goal is to restrict the amount of food consumed and alter the
normal digestive process, but to a much greater degree. The anatomy of the small intestine is changed to divert the bile and pancreatic juices so they meet the ingested food closer to the middle
or the end of the small intestine.With the three approaches discussed below, absorption of nutrients and calories is also reduced, but to a much greater degree than with previously discussed
procedures. Each of the three differs in how and when the digestive juices (i.e., bile) come into contact with the food.
Since food bypasses the duodenum, all the risk considerations discussed in the gastric bypass section regarding the malabsorption of some minerals and vitamins also apply to these techniques,
only to a greater degree