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What Happens During Weight Loss Surgery?

Malabsorptive Weight Loss Surgery: Gastric Bypass and Billiopancreatic Bypass continued...

Instead, the pouch empties directly into the small intestine. To make this work, the small intestine is severed. The surgeon connects one end of it to an opening in the new stomach pouch.

The food bypasses most of the stomach and the first part of your small intestines. Therefore, this surgery is both restrictive and malabsorptive. Few purely malabsorptive operations are done in bariatric surgery today.

The one up-to-date technique labeled as malabsorptive is called a "billiopancreatic diversion with duodenal switch." This operation is similar to a gastric bypass, but has some major differences. First, it involves completely removing much of the stomach, not just sealing off part of it. Second, pancreatic juices enter near the end of the small intestine, close to the colon (large intestine).

How Does Weight Loss Surgery Work?

Bariatric surgery causes weight loss mainly by forcing you to eat less. After surgery, you simply can't consume enough calories to keep your weight up. With a tiny stomach pouch, overeating is physically impossible, or at least extremely uncomfortable. Also, what little you do eat gives a long-lasting feeling of fullness, so you tend to eat less frequently.

Malabsorption may discourage you from eating greasy or sugary food. Bypassing part of the small intestine prevents some fat from being digested, causing severe diarrhea. Eating food with high sugar content can cause an attack of nausea, gut pain, and diarrhea known as "dumping syndrome." People who've had bariatric surgery learn to change their diet to avoid these side effects. Doing so rules out many foods that are also high in calories.

Scientists have also recently discovered that bariatric surgery may cause hormonal changes and effects on the nervous system that suppress appetite, too. Much about how these changes relate to weight loss is still unknown.

Deciding on Weight Loss Surgery

Before you have weight loss surgery, you'll go through an evaluation process that includes counseling and various tests. It's not an operation that anyone gets on a whim. "It's something that most people have been thinking about for years," says Kelvin Higa, MD, president of the American Society for Metabolic and Bariatric Surgery.

One-on-one counseling that takes all your individual needs and preferences into account can help you choose the best type of bariatric surgery for you. "One size does not fit all," Higa tells WebMD.

Your doctor may strongly prefer a certain operation, but at least for now there isn't a generally accepted "gold standard" in weight loss surgery, Higa says.

Gastric bypass, gastric banding, gastroplasty, and biliopancreatic diversion all have pros and cons. Those that involve more cutting, sewing, and rearranging things inside of you may yield slightly better results, but they also may come with more side effects.

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