Obese people who find it impossible to lose weight may benefit from a new surgery that reduces appetite and cuts the amount of food that the body absorbs.

The Lahey Clinic's Dr. Paresh Shah recently told a meeting at the Leopards Club that there are several safe and effective surgical options currently available to change the body's physiology to help gain lasting weight control.

He said: "Some procedures are restrictive, meaning that they restrict the amount of food the stomach can hold.

"An example would be vertical gastroplasty, or stomach stapling, while other procedures achieve the effect with malabsorption, in which the body's absorption of nutrients and calories was limited.

"The classic example of this type is the bilio-pancreatic diversion (BPD) or duodenal switch, which was pioneered in Italy."

But Dr. Shah said the gastric bypass, sometimes referred to as Roux en-Y, is the only bariatric procedure which combines both volume restriction and malabsorption.

"It reduces the amount of food that can be consumed at one time and the number of calories that can be absorbed from each meal," said the doctor.

"At present, gastric bypass is considered the gold standard of the bariatric procedures and is also the most common weight loss surgery performed in America."

He said that during a gastric bypass surgery, the bariatric surgeon creates a tiny, thumb-sized pouch at the top of the stomach, from which the rest of the stomach is divided and separated.

"A segment of the small intestine, or bowel, is then attached to this pouch allowing food to bypass the separated, larger portion of the stomach as well as the first part of the small intestine.

The new outlet from the stomach to the intestine is deliberately small to slow down the flow of food out of the stomach and this preserves the flow of digestive juices.

Dr. Shah told the audience that the distal gastric bypass is a modification of the procedure in which the stomach pouch is attached lower on the small intestine.

He said: "Food travels through a shorter length of intestine, and patients typically lose more weight, due to the greater malabsorption. Distal gastric bypass carries a higher risk of malnutrition, however, physicians tend to recommend it only to the super-obese or as a revision to the unusual patients who fail to lose significant weight with a standard gastric bypass."

He said there are two ways that the procedures can be carried out and these are either open surgery or the laparoscopic approach.

Dr. Shah said: "The surgeon can access the stomach and intestines one of two ways.

"In the conventional method, known as open gastric bypass, the surgeon would make a large incision in the upper abdomen and up until 1993, this was the only way that gastric bypass was performed."

But Dr. Shah and other surgeons now use a newer and less-invasive alternative - the laparoscopic approach, a technique that was first used in Bermuda in the early 1990s by the late Dr. John Stubbs and Dr. Wolfgang Spangengerger.

"It uses several tiny incisions instead of one large one," he said. "I use a pencil-thin viewing telescope and camera, which is inserted into the abdominal cavity.

"The area is viewed on an overhead television monitor and special long, slender instruments are introduced through additional small incisions.

"These are used to conduct the operation while the surgeon views the image obtained by the telescope of the internal organs.

"The laparoscopic gastric bypass can take longer to perform and requires more training on the part of the surgeon, when compared to the open approach," added Dr. Shah.

"Yet it offers several advantages, including shortened hospitalisation, reduced post-operative pain, and less scarring."

Dr. Shah warned that not all patients qualify for the laparoscopic approach. Severe obesity may make the technique unfeasible if the surgical instruments are not long enough to reach the stomach.

And patients who have undergone previous open surgery in the upper abdomen may not be good candidates.

"In some cases, the operation may be begun laparoscopically, but subsequently require conversion to an open procedure," Dr. Shah said.

He said that after the operation, gastric patients experience an earlier feeling of fullness when eating due to the small size of their new stomach pouch.

He said: "Even after a few bites, you may feel completely satisfied and on top of that, some of the calories consumed will not be absorbed by the body.