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Gastric Bypass

Gastric Bypass Surgery or Laparoscopic Banded Gastric Bypass Surgery (LBGBP) is described as the ‘gold standard’ in bariatric surgery and is one of the most frequently performed bariatric procedures worldwide. When eating, the stomach is bypassed so that food enters a small gastric pouch and then enters a loop of the small bowel for digestion.

What is gastric bypass surgery?

Gastric Bypass has been described as the ‘gold standard’ weight control operation and has been the most frequently performed bariatric (obesity) procedure worldwide. It is the operation to which all other bariatric procedures are compared, and it has the best – and best known – long-term results.

Laparoscopic Banded Gastric Bypass Surgery (LBGBP) is a procedure for the treatment of obesity. It consists of a thumb-sized vertical gastric pouch attached to the small bowel, to bypass more than 95% of the stomach. There are several different types of gastric bypass surgery available. Please refer to our Information Booklet (you can download at the bottom of this page) for more detailed information. These are the Roux-en-Y Gastric Bypass (banded or unbanded) and the Mini or one-anastomosis Gastric Bypass (banded or unbanded).

How does gastric bypass surgery work?

The operation is truly a bypass of the stomach. Most of the stomach is bypassed (unlike the Sleeve, where most of the stomach is removed) so that food eaten goes into a small gastric pouch (15-30mL) and then into a loop of the small bowel (the jejunum) for digestion.

How the Gastric Bypass causes weight loss

Weight is lost by the following four mechanisms:

  1. Satiety (being satisfied early in a meal) is induced by the small stomach and through the ‘switching off’ of the hormones that cause hunger. Many patients go for months before they have any recognisable hunger sensations, and they often have to remind themselves to eat.
  2. Overeating is limited by the new small and tight stomach. Too much food causes discomfort and vomiting. If possible, A/Prof Talbot usually puts a silicone ring around the stomach, which helps prevent the stomach from stretching up in the future (the banded bypass).
  3. The operation often causes intolerance to sweets and high-density carbohydrates as well as fatty, oily food. These foods run quickly into the small bowel and cause unpleasant symptoms called ‘dumping’.
  4. There is trivial malabsorption of fat, as the food eaten is initially not mixed with bile and pancreatic juice. There is no protein or carbohydrate malabsorption.
Illustration of Gastric Bypass surgery

Effectiveness of gastric bypass surgery in causing weight loss

The operation allows the average patient to lose 25-50% of their total weight in 18-24 months. After this period, most patients regain some weight. This weight gain occurs for a variety of reasons, including poor compliance with diet and exercise and physiological adaptation of the body to the operation. At 5, 10 and 15 years the weight loss has been shown to stabilise at a level where most people are happy. Weight regain may be preventable through dietary compliance.

While these operations are very powerful, most people do not end up in the “normal” weight range (BMI below 25). Instead, it is more common for them to settle around the BMI 28-32 level which is a perfectly healthy weight for the majority of patients.

Suitable candidates for gastric bypass surgery

As with all obesity surgeries, the Gastric Bypass should only be performed on people with a BMI greater than 40, or those with a BMI over 35 with other medical co-morbidities such as diabetes or high blood pressure. Patients who are lighter than this run the risk of losing weight but at the expense of complications that can make them worse off. They should have tried other weight loss therapies beforehand but been unable to keep the weight off. Patients with eating disorders such as binge eating or a nocturnal eating disorder, and patients who habitually graze or emotionally eat, need to seek treatments for these disorders as well, otherwise the surgery will fail after being initially successful.

Gastric bypass surgery, unlike a sleeve gastrectomy, is reversible. The stomach and bowel can be reconnected, although this requires another operation.

If you are considering a gastric bypass as a potential bariatric surgery and would like more information, please contact our clinic today, and one of our expert team will be happy to discuss this further with you. You should also download (below) our Gastric Bypass Surgery Information document.

Illustration of Gastric Bypass surgery

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Free Bariatric Surgery Information Webinar

Join our free Bariatric Surgery Information Webinar and Q&A on the first Tuesday of each month at 7.30pm (Sydney time).

Robotic Surgery

Do you need more information?

If you would like to speak to one of our specialised team or enquire about making an appointment at our clinic,
please call 02 9553 1120 or submit an enquiry.

Free Bariatric Surgery Information Webinar

Join our free Bariatric Surgery Information Webinar and Q&A on the first Tuesday of each month at 7.30pm (Sydney time).

Robotic Surgery

Contact Us.

For appointments please call us.

Complimentary Inclusions In Our Bariatric Aftercare Package

(included in your clinic fee)

Siara Health program providing information regarding surgery and aftercare.

2 appointments with our Dietitian Tania Chaanine.

BSc Nutrition & Dietetics (Honours)

Enrollment to the Fresh Start Program to support you for 2 years post-operatively.

Copy of Your Complete Guide to Nutrition for Weight Loss Surgery book by Sally Johnston.

1 month supply of bariatric multi vitamins – BN Multi.

Portion Perfection bariatric plate & bowl, to help you at meal times.

BMI Calculator

BMI is a useful tool for calculating whether you are a healthy weight for your height. If you enter your height and weight below our calculator will provide you with your own BMI. BMI is an effective measurement tool, however it is only one of the factors we look at when examining the relationship between someone’s weight and health. If you are concerned about your BMI please get in touch with one of our helpful team today who will be happy to discuss this with you.