Generally this operation is for people who are about 100 pounds (45 kg) over their "ideal weight."

After a gastric bypass, the likely long-term weight loss varies from person to person. Significant weight loss in the short term is normally expected but long-term weight loss is more important.

Patients who are very heavy and those patients that are only slightly overweight, lose weight at different rates.

A patient who weighs 600 pounds is unlikely to achieve a weight close to ideal with any bariatric operation. Such a patient may lose 300 pounds or about 60% of excess weight.

A patient who weighs 220 pounds would be expected, to lose a higher percentage of excess weight that a person whose weigh is 320 pounds.

The skinnier you are, the more likely you can achieve a weight closer to your ideal.

This operation is usually very successful. Many patients lose over 100 pounds (about 45 kg) within the first 18 months following surgery. It should however be accompanied by an exercise schedule.

It is normal to gain some weight back after 2 years. The amount of weight regain is difficult to predict. On average, patients regain 10-15% of their excess weight back in the long term.

The gastric bypass surgery has been performed for about 50 years. Surgeons are therefore comfortable with the risks and benefits of the surgery.

Benefits of Gastric Bypass

This operation is good for long-term weight loss.

Half of all the weight loss often occurs in the first six months.

The average weight loss peaks at 18-24 months after surgery.

The surgery improves or cures diabetes, hypertension, arthritis, venous stasis disease, certain types of headaches, heartburn, sleep apnoea and other weight related disorders.

It has also demonstrated significant improvements in quality of life for the patients who under go it. See stomach surgery for a list of more benefits.

Risks, Complications and Side Effects of Gastric Bypass

The risk of you dying during the surgery or soon thereafter is about 2%. About 1% of patients suffer immediate complications and death.

Another 1% will have post-operative complications that lead to death within one month of surgery. This can be lessened by following the surgeon's post-operative plan and using a doctor who has performed many procedures.

An anastomotic leak and a pulmonary embolism are the most common causes of death after a gastric bypass.

An anastomotic leak is deadly if not recognized and treated early. It occurs when intestinal fluids leak out into the abdomen. Symptoms of a leak include severe chest pain, anxiety, heart palpitations, shortness of breath, and abdominal pain.

A pulmonary embolism is caused from a blood clot that forms in the leg. It then breaks off and is lodged in the lungs. Prevention is important to avoid this complication. Blood thinners, leg compression devices and early walking will help to prevent blood clots.

The open operation usually has a higher frequency of wound problems such as infections and wound hernias than the laparoscopic operation.

About 25% of patients undergoing this gastric bypass will have some form of post-operative complication such as hernia or gallstones. These would require either a further procedure or change in habits.

In some instances, the production of intrinsic factor in the stomach wall to help in vitamin B12 absorption is decreased. This requires either B12 injections or sub-lingual tablets for life to help in the breakdown of food for energy.

Other risks and side effects of gastric bypass include:

Other complications include bowel obstruction, strictures, ulcers, bleeding and prolonged nausea.

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