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Bariatric Surgery Overview
Last Updated: Nov. 1, 2003
Severe obesity is a chronic condition that is difficult to treat through diet and exercise alone. Gastrointestinal surgery, also called bariatric surgery, is the best option for people who are severely obese and cannot lose weight by traditional means or who suffer from serious obesity-related health problems.
The surgery promotes weight loss by restricting food intake and, in some operations, interrupting the digestive process. As in other treatments for obesity, the best results are achieved with healthy eating behaviors and regular physical activity.
Who is a candidate for surgery?
People who may consider gastrointestinal surgery include those with a body mass index (BMI) above 40 – about 100 pounds of overweight for men and 80 pounds for women. People with a BMI between 35 and 40 who suffer from type 2 diabetes or life-threatening cardiopulmonary problems such as severe sleep apnea or obesity-related heart disease may also be candidates for surgery.
How the surgery was developed
The concept of gastrointestinal surgery to control obesity grew out of results of operations for cancer or severe ulcers that removed large portions of the stomach or small intestine. Because patients undergoing these procedures tended to lose weight after surgery, some physicians began to use such operations to treat severe obesity.
The first operation that was widely used for severe obesity was the intestinal bypass. This operation, first used 40 years ago, produced weight loss by causing malabsorption. The idea was that patients could eat large amounts of food, which would be poorly digested or passed along too fast for the body to absorb many calories. The problem with this surgery was that it caused a loss of essential nutrients and its side effects were unpredictable and sometimes fatal. The original form of the intestinal bypass operation is no longer used.
Gastrointestinal surgery alters the digestive process. The operations promote weight loss by closing off parts of the stomach to make it smaller. Operations that only reduce stomach size are known as “restrictive operations” because they restrict the amount of food the stomach can hold.
Some operations combine stomach restriction with a partial bypass of the small intestine. These procedures create a direct connection from the stomach to the lower segment of the small intestine, literally bypassing portions of the digestive tract that absorb calories and nutrients. These are known as malabsorptive operations.
There are several types of restrictive and malabsorptive operations. Each one carries its own benefits and risks.
Restrictive Operations
Restrictive operations serve only to restrict food intake and do not interfere with the normal digestive process. To perform the surgery, doctors create a small pouch at the top of the stomach where food enters from the esophagus. Initially, the pouch holds about 1 ounce of food and later expands to 2-3 ounces. The lower outlet of the pouch usually has a diameter of only about 3⁄4 inch. This small outlet delays the emptying of food from the pouch and causes a feeling of fullness.
As a result of this surgery, most people lose the ability to eat large amounts of food at one time. After an operation, the person usually can eat only 3⁄4 to 1 cup of food without discomfort or nausea. Also, food has to be well chewed.
Restrictive operations for obesity include adjustable gastric banding (AGB) and vertical banded gastroplasty (VBG).
Malabsorptive Operations
Malabsorptive operations are the most common gastrointestinal surgeries for weight loss. They restrict both food intake and the amount of calories and nutrients the body absorbs. The two operations are called Roux-en-Y gastric bypass (RGB) and biliopancreatic diversion (BPD).
Source: National Institutes of Health
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