Gastric Bypass

On video: Roux-en-Y gastric bypass procedure

The Roux-en-Y gastric bypass is a combined restrictive/malabsorptive operation, which restricts both food intake and the amount of calories and nutrients the body absorbs. In this operation, the surgeon creates a small pouch at the top of the stomach to restrict food intake. Next, the pouch is connected to a Y-shaped section of the small intestine (called the Roux limb), allowing food to bypass the lower stomach, the duodenum and jejunum (the first two parts of the small intestine). At NYU, we perform most gastric bypasses using a laparoscopic approach, using 5-6 small skin incisions.


  • Weight loss ranges from 60 to 80 percent of excess body weight within two years.

  • Most co-morbidities - such as diabetes, high blood pressure, sleep apnea, and high cholesterol - improve after the surgery, and some even disappear.

  • A side effect called dumping syndrome -in which the contents of the stomach empty rapidly into the small intestine - may occur after gastric bypass. This is a common consequence of eating concentrated sweets or carbohydrates. The symptoms of dumping syndrome include profuse sweating, nausea, dizziness, palpitations, abdominal pain and weakness. This is actually a desired side effect of the surgery, since it discourages patients from eating sweets. However, dumping syndrome happens in only 30 percent of patients.


  • Roux-en-Y surgery is generally safe, but it can lead to serious and potentially fatal complications. In a gastric bypass, the stomach and intestines are cut and then reconnected using staples and stitches, which have the potential to tear in the first few weeks after surgery. This is known as a ‘leak’. This can lead to peritonitis, internal infection or bleeding.

  • Intestinal blockage, due to scar tissue or intestinal twisting, is a possibility.

  • After two years, some patients regain 10 to 30 pounds of weight they previously lost due to stretching of the pouch and its outlet. This results in return of appetite and loss of satiety.

  • The Roux-en-Y operation causes food to bypass areas of the small intestine that are responsible for absorbing protein, calcium, and certain vitamins. In addition, less iron is absorbed. To avoid nutritional deficiencies, you will need to take daily vitamin and mineral supplements everyday for the rest of your life, including a multivitamin, calcium, Vitamin B12, and iron. You will also need to increase the proportion of protein in your diet, since you'll be eating less food overall. Blood tests must be performed every three months for the first year to check your nutritional status.