The gastric bypass operation is performed by laparoscopic surgery to reduce the stomach and cause food to go directly from this reduced stomach towards the end of the intestine (“bypassing” most of the intestine, hence its name).
The surgery involves two stages:
First, the stomach is reduced from about 1000 CC in an obese person to about 50 CC, dividing it into two parts at its highest point: the smallest part of the stomach receives the food that comes from the mouth and the “residual” part that continues secreting the biliopancreatic juices.
The second part of the intervention is bridging the intestine so that the secretion of biliopancreatic juices and food join at 75-200 cm from the stomach and, therefore, a great portion of the ingested food DOES NOT get absorbed. For this purpose, the intestine is also divided and part of it joins the small stomach and another part is rerouted at a distance of 75-200 cm. The malabsorption produced by this technique is the reason for weight loss success but in view of the risks that it poses it should only be used in selected patients.
For optimal results, it is necessary that the patient follows some recommendations regarding his diet. The diet after gastric bypass is liquids during the first two weeks; then, you advance to a soft diet, and then, to a normal diet, making these changes gradually. By diverting the normal route of food absorption, it is necessary to take multivitamins and calcium permanently and indefinitely because the absorption of these gets altered by surgery.