Bariatric surgery may be done on people who:

  • Are morbidly obese (BMI over 40) and cannot lose weight by traditional means
  • Have a BMI over 35 with weight-related health problems such as type 2 diabetes, orthopedic problems, cardiovascular disease, or severe sleep apnea
  • Have a BMI over 30 with weight-related health problems if laparoscopic adjustable gastric banding will be done

This type of surgery promotes weight loss by reducing the size of the stomach to restrict food intake or by interrupting the digestive process. It may be a good option for people who are unable to lower their weight by other means. After surgery, the best long-term results are achieved with proper diet and regular physical activity.

A thorough evaluation, which includes your nutritional status, will be done before discussing surgical options. You must have also have made multiple attempts to lose weight with other treatments. It is likely that you will meet with a dietitian who will help you to prepare for the dramatic change in your eating habits that will occur after surgery. You will learn how to balance sound nutrition with smaller portions. This is because you will not be able to eat very much at each sitting after surgery.

The 2 main types of weight loss surgery are:

  • Restrictive procedures—to decrease the capacity of the stomach
    • Laparoscopic adjustable gastric banding (AGB)
    • Vertical sleeve gastrectomy (VSG)
    • Vertical banded gastroplasty (VBG)
    • A temporary balloon device that occupies space in the stomach (an endoscopic procedure)
  • Malabsorptive procedures—to shorten the small intestine's length, which reduces the absorptive surface
    • Laparoscopic Roux-en-Y gastric bypass (RGB)—this is both a restrictive and malabsorptive procedure
    • Biliopancreatic diversion (BPD)

Restrictive Procedures

Restrictive operations restrict food intake and do not interfere with the normal digestive process. To do the surgery, doctors create a small pouch at the top of the stomach where food enters from the esophagus. As a result of this surgery, most people lose the ability to eat large amounts of food at one time and food must be well chewed.

Although restrictive operations lead to weight loss in most people, they are less successful than malabsorptive operations in achieving substantial, long-term weight loss. Some people will regain weight. Others are unable to adjust their eating habits and fail to lose the desired weight. Successful results depend on your willingness to adopt a long-term plan of healthy eating and regular physical activity.

Restrictive operations for obesity include:

Vertical Sleeve Gastrectomy

In this procedure, your doctor will place a row of staples down your stomach. This will reduce your stomach to a banana size pouch. The remaining part of the stomach (about 80-85%) will then be removed.

This procedure is often done as a laparoscopic surgery. With this type of surgery, only small incisions are needed. Tiny surgical instruments including a camera will be passed through these incisions. The doctor can use these tools to complete the surgery. An open surgery may be needed for some. During an open surgery a larger incision is needed. The incision will allow your doctor to see the stomach and surrounding area.

Adjustable Gastric Banding (AGB)

In this procedure, a hollow band made of special material is placed around the stomach near its upper end, creating a small pouch and a narrow passage into the larger remainder of the stomach. The band is then inflated with a salt solution. It can be tightened or loosened over time to change the size of the passage by increasing or decreasing the amount of salt solution. After this procedure, weight loss averages 50% of excess body weight. This loss is sustained over the long-term.

Adjustable Gastric Banding
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Vertical Banded Gastroplasty (VBG)

In VBG, both a band and staples are used to create a small stomach pouch. This procedure is less commonly done now due to less weight loss and higher complications.

Possible Complications

A common complication of restrictive operations is vomiting. This is caused when the small stomach is overly stretched by food particles that have not been chewed well. After laparoscopic AGB, patients complained of side effects, including abdominal pain, heartburn, nausea, band slippage, or band erosion.

Risks of VBG include wearing away of the band and breakdown of the staple line. In a small number of cases, stomach juices may leak into the abdomen, requiring emergency surgery. In less than 1% of all cases, infection or death may occur.

Malabsorptive Procedures

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.

Malabsorptive operations produce more weight loss than restrictive operations and are more effective in reversing the health problems associated with severe obesity. Patients who have malabsorptive operations generally lose two-thirds of their excess weight within 2 years.

Malabsorptive operations for weight loss include:

Roux-en-Y Gastric Bypass (RGB)

RGB is the most common and successful type of malabsorptive surgery. First, a small stomach pouch is created to restrict food intake. Next, a section of the small intestine is attached to the pouch to allow food to bypass the lower stomach, the first segment of the small intestine, called the duodenum, and the second segment of the small intestine, known as the first portion of the jejunum. This bypass reduces the amount of calories and nutrients the body absorbs.

Gastric Bypass
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Biliopancreatic Diversion (BPD)

In this more complicated malabsorptive operation, portions of the stomach are removed. The small pouch that remains is connected directly to the final segment of the small intestine, completely bypassing the duodenum and the jejunum. Although this procedure successfully promotes weight loss, it is less frequently used than other types of surgery because of the high risk of nutritional deficiencies. A variation of BPD includes a “duodenal switch,” which leaves a larger portion of the stomach intact, including the pyloric valve that regulates the release of stomach contents into the small intestine. It also keeps a small part of the duodenum in the digestive pathway.

Possible Complications

In addition to the risks of restrictive surgeries, malabsorptive operations also carry greater risk for dietary deficiencies. This is because the procedure causes food to bypass the duodenum and jejunum in the small intestine, where most iron, calcium, and other nutrients are absorbed. Menstruating women may develop anemia because not enough vitamin B12 and iron are absorbed. Decreased absorption of calcium may also lead to osteoporosis and metabolic bone disease. Nutritional supplements are required to help prevent these deficiencies. Patients who have the BPD must also take fat-soluble vitamins A, D, E, and K supplements.

RGB and BPD operations may also cause “dumping syndrome,” which means that stomach contents move too rapidly through the small intestine. Symptoms include nausea, weakness, sweating, faintness, and sometimes diarrhea after eating.

The more extensive the bypass, the greater the risk of complications and nutritional deficiencies. Those with extensive bypasses of the normal digestive process require close monitoring and life-long use of special foods, supplements, and medications.

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