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Gastric Bypass Surgery

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A 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.  the pouch is then connected to a Y-shaped section of the small intestine (the Roux limb), allowing food to bypass the lower stomach, the duodenum and jejunum (the first two parts of the small intestine).


  • Weight loss approx. 60 - 80% 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 are even cured.

  • 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, and weakness. This is actually a desired side effect of the surgery, since it discourages patients from eating sweets.  Dumping syndrome happens in 30% of patients.


  • Whilst Roux-en-Y surgery is generally safe, 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 to the potential to tear in the first few weeks after surgery. This can lead to peritonitis and bleeding.

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

  • After about two years the pouch can stretch sufficient so that some patients regain some of the weight they previously lost.

  • 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 because of the small size of the new stomach pouch.  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.

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