Gastric Bypass (Roux-en-Y)

Roux-en-Y gastric bypass is the current gold standard procedure for weight loss surgery and is also the most frequently performed. It has proven to be very effective in helping patients lose weight and keep it off.

During Gastric Bypass Roux-en-Y surgery the capacity of the stomach is reduced by creating a smaller stomach pouch with tiny outlet to reduce the speed at which food leaves the stomach. Consequently, after undergoing the procedure patients feel full after only eating a small portion of food and remain satisfied for longer after eating.

The procedure

As with most other forms of weight loss surgery, a gastric bypass should only be considered when all other traditional methods of weight loss have been attempted without success. Ideal patients should be over 18 and should be morbidly obese (BMI of 40 or greater). Patients less severely overweight may be considered if they are suffering from some other obesity related disease, such as type II diabetes or cardiovascular disease.

Roux-en-Y gastric bypass is typically performed using laparoscopy (in which small incisions are used to perform the operation), however an open procedure may be required in certain cases. During the operation staples are used to section off a portion of the stomach creating a small pouch. The pouch, which has a capacity of approximately 30 grams and empties directly into the small intestine, is then separated from the stomach and the stomach sewn closed. The pouch is reattached to the small intestine by dividing the small intestine at the level of the jujunum (the middle portion of the small intestine) and reattaching the free end into the side of the newly formed pouch. The portion of intestine which remains attached to the stomach is then sewn closed and stapled to the newly formed digestive tract. The operation is performed under general anaesthetic and typically takes 2 – 3 hours to complete depending on whether laparoscopy or open surgery is used. (Laparoscopic surgery takes longer complete).

The result of the surgery is the bypassing of the stomach and a marked reduction in the length of the small intestine. The smaller pouch not only means that you will feel fuller quicker but also reduces the capacity of the digestive tract to absorb nutrients and calories resulting in significant weight loss over the following years.

After your surgery

Following your surgery you will likely spend 2 -4 days in hospital and return to everyday activities within 2 -3 weeks. Once again, recovery time is dependent on which surgical method is used as open surgery typically requires a longer stay in hospital and an extra week or so away from work.

Initially your diet will be restricted to clear liquids with pureed food beings reintroduced slowly. Such soft foods can easily travel through the newly formed pouch and digestive tract. Eventually, after approximately 30 days a transitional diet can be adopted consisting of both pureed foods and certain solid table foods. During this stage patients are often susceptible to dehydration so ensuring an adequate intake of fluids is essential. Typically about 6 months after surgery you will be following a long-term maintenance diet which you will likely maintain for the rest of your life.

Long term outcome

A year after surgery you can expect an average weight loss of approximately 70% of excess body weight with the majority of patients maintaining a loss of 50-60% of excess body weight after 2 years.

The small pouch fills up rapidly reducing the amount of food consumed at meal times. Furthermore, due the reduced absorptive capacity of the newly formed digestive tract, dumping symptoms (when food is rapidly dumped into the small intestine) commonly occur in response to a large meal or food with a high sugar or fat content. Although not a serious risk dumping can cause nausea, faintness and diarrhoea providing an effective deterrent from high fat and high sugar foods promoting even more rapid weight loss.

Additional benefits include the resolution of the majority of certain related health conditions such as diabetes, depression, sleep apnoea and high blood pressure.


As with all major surgery there are several predisposing factors that patients should consider before opting for surgery. Risk is increased in older patients and in patients who already have an existing obesity related disease. Male patients and patients with a BMI of 50 or more are also placed at greater risk.

There are several complications that may arise as a result of surgery, some of which can have serious consequences. Leakage from the connection between the pouch and the small intestine and pulmonary emboli are both complications that although are very rare can potentially be very dangerous. Less serious complications include the risk of infection and blood loss requiring transfusion. Furthermore, approximately 15% of patients develop gallstones and another 20% require follow-up operations for complications such as hernias.

Nutritional deficiency may also occur resulting in illnesses such as iron deficient anaemia, pernicious anaemia (a deficiency of vitamin B12), osteoporosis or metabolic bone disease. Such illnesses however can be treated relatively easily and effectively by maintaining a healthy diet accompanied by additional nutritional supplements such as oral iron or B12.


The Roux-en-Y gastric bypass procedure typically costs $19000 - $25000.

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