During the gastric bypass procedure, the surgeon staples off the majority of the stomach, leaving a much smaller compartment. Because of the new, smaller stomach size, the patient can only eat much smaller amounts of food than they were able to eat before the procedure. The new stomach compartment can only accommodate a few ounces of food at a time. The result is weight loss.
A negative effect of gastric bypass surgery is that some of the nutrients and calories contained in the foods consumed won’t be absorbed by the body. The reason for this is that most of the stomach and some of the small intestine have been circumvented. This is usually overcome with the use of nutritional supplements.
Gastric bypass surgery is considered a good treatment for candidates who exceed their ideal weight by at least 100 pounds. In addition to surgery, patients must commit to lifelong changes in diet and exercise following gastric bypass.
The expected weight loss in the first 1-2 years after a Roux-en-Y gastric bypass is 50-77% of total desired weight loss. Research indicates that, after 10-14 years, 50-60% of weight lost has remained off in many patients following gastric bypass surgery. A 2000 research project that included five hundred patients indicated that 96% of specific health conditions associated with morbid obesity (diabetes, depression, back pain, sleep apnea, high blood pressure) were improved or eliminated. The length of hospital stays required following gastric bypass is usually 48 hours. And most patients return to normal activity within the two weeks following surgery.
The benefit of gastric bypass Surgery that brings weight loss by decreasing intestinal absorption of food also brings risk of nutritional deficiency. That’s because, instead of following the usual path, food bypasses part of the stomach and small bowel. In addition to complications that can come with surgery, some people see continuing deficiencies of vitamin B12, folate, and iron. In addition, a side effect called "Dumping Syndrome" (sugar consumption causing abdominal cramping and diarrhea), can also result. And unless patients make permanent lifestyle changes, they may regain weight in the years following surgery.