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  • Q&A with Australian Health Practitioners

    What is gastric bypass surgery?

    Related Topic
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  • 1


    Christina Turner

    Dietitian, Nutritionist

    Christina is an Accredited Practising Dietitian who specialises in working with community members living with Eating Disorders. She currently provides online consultations. View Profile

    In simple terms, gastric bypass surgery is where surgery is performed so that food  bypasses the stomach. This means when food is eaten it goes further down into the small intestine (and  misses the stomach).

    Generally speaking the idea behind this type of surgery, is to the reduce the amount of food people who are Obese are able to eat and in doing so, help with weight loss.

    The Obesity Surgery Society for Australia and New Zealand is a great place to check out information on the different types of surgery.

  • 1


    Arlene is a registered practising dietitian, with a private practice in the Eastern Suburbs of Sydney, and has built a strong business over the last … View Profile

    Gastric bypass surgery – where most of the stomach is bypassed and a small stomach pouch is made – is the most commonly performed weight loss surgery today. As performed today, gastric bypass surgery has two parts:

    1. Creation of a small stomach pouch
    During this part of the surgery, the stomach is divided into a large portion, and a much smaller portion. The small part of the stomach is then sewn or stapled together to make a small pouch (this part is sometimes called stomach stapling“). The small stomach pouch can only hold a cup or so of food. With such a small stomach, people feel full quickly and eat less. This strategy is also called ”restrictive," since the new stomach size restricts food intake.
    1. Creation of bypass
    In this part of the surgery, the new, small stomach pouch is disconnected from the first part of the small intestine (the duodenum). The surgeon then reconnects the stomach to a portion of intestine slightly further down (the jejunum). This surgical technique is called a “roux-en-Y.”
    After a roux-en-Y, food passes directly from the stomach into the jejunum, bypassing the duodenum. This leads to reduced absorption of calories and nutrients. This weight loss method is called “malabsorptive.”
    Stomach stapling and gastric bypass are typically performed during the same surgery. Together, this surgery is called a “roux-en-Y gastric bypass.” Usually, gastric bypass is performed laparoscopically (using tools inserted through small incisions in the belly). When laparoscopy is not possible, gastric bypass can be open (laparotomy). This involves a large incision in the middle of the belly.
    After bypass surgery the following can be expected:
    Nearly 10% of people have complications after gastric bypass surgery. These are usually minor and include: Wound infections, Digestive problems, Ulcers, Bleeding
    Nearly 1% to 5% of people have serious or life-threatening complications after gastric bypass surgery, such as: Blood clot (pulmonary embolism), Heart attack, Leak in the surgical connections with the intestines, Serious infection or bleeding
    The risk of complications is lower at centers that perform more than 100 weight loss surgeries per year. And, when performed by a highly experienced surgeon, deaths in the month following gastric bypass surgery are rare: about 0.2% to 0.5% (less than one in 200 people).
    After gastric bypass surgery, people typically stay in the hospital for two to three days and return to normal activity within two to three weeks.
    Weight Loss
    Weight loss after gastric bypass surgery is often dramatic. On average, patients lose 60% of their extra weight. For example, a 170 kg person who is 90 kg  overweight would lose about 60kg.

  • Dr Kenneth Wong

    Bariatric (Obesity) Surgeon, General Surgeon, Laparoscopic Surgeon

    Dr Ken Wong is a very experienced specialist surgeon focussing on keyhole surgery techniques for gallstones, bowel cancer, hernia and weight loss surgery. He graduated … View Profile

    Gastric bypass surgery is one of three main forms of weight loss surgery conducted in the world.

    The other two are the gastric sleeve and the gastric band.

    Gastric bypass surgery involves re-routing the bowel such that large segments of the bowel are bypassed and hence food is not absorbed. Weight loss is created by minimising the absorption of nutrients from food.

    Whilst gastric bypass surgery probably achieves the greatest weight loss, it also has the highest risk profile of all three forms of weight loss surgery.

    The risks can include short term surgical risks such as bowel twisting, leaking of bowel joins, narrowing of the bowel joins and longer term risks such as osteoporosis, brittle teeth and hair falling out.

    For individualised advice on which form of weight loss surgery is best suited for each person, it is best to consult an experienced weight loss surgeon.

    Ken Wong

  • 1


    Dr Steven Leibman

    Bariatric (Obesity) Surgeon, General Surgeon, Laparoscopic Surgeon, Upper GI Surgeon (Abdominal)

    Dr Leibman is a general, upper gastrointestinal and bariatric (weight loss) surgeon. Dr Leibman's surgical interests include surgery for gallstone disease, hernias, gastro-oesophageal reflux disease, … View Profile

    The gastric bypass (of which there are some varieties) involves reducing the size of the stomach without removing any of it, as well as joining part of the intestine back onto the smaller stomach so that food is diverted away from the top part of the intestine. This adds an element of “malabsorption” to the restrictive component of the operation and for a long time has been considered the gold standard weight loss operation against which others have been compared. While it is a larger and technically more challenging procedure, the weight loss results are excellent and the health improvements very significant. It is, however, more likely to be associated with the possibility of long term nutritional deficiencies if close attention to diet and vitamin replacement are not adhered to.

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