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There are two types of bariatric surgery performed today: restrictive operations and restrictive/malabsorptive operations.

Restrictive operations reduce food intake by narrowing the passage between the upper and lower parts of the stomach. This limits the amount of food that can be held in the stomach (to about one ounce) and delays the passage of food through the stomach. Restrictive operations do not interfere with the normal digestive process.

The two major types of restrictive operations include:

• Adjustable gastric banding (AGB). A hollow band of silicone rubber is placed around the upper end of the stomach. This creates a small pouch and a narrow passageway into the rest of the stomach. Once the band is in place, a connecting tube is used to inflate it with a salt solution. The size of the passage can be altered by increasing or decreasing the amount of salt solution.
  

  

• Vertical banded gastroplasty (VBG). A band is combined with staples to create a small stomach pouch. This procedure is not as common as it once was and typically results in less weight loss than bariatric surgery with a malabsorptive component.

  

The restrictive procedures are often performed using a laparoscope, which involves smaller incisions and shorter recovery time than traditional surgery. 

Malabsorptive operations, also known as intestinal bypasses, alter the small intestine so that much of it is not involved in the digestive process. This reduces the amount of calories and nutrients absorbed from food. Today, experts usually do not recommend these procedures because they can result in nutritional deficits for the patient.

Although pure malabsorptive operations are no longer recommended, many patients undergo a combined restrictive/malabsorptive operation. In fact, these are the most commonly performed bariatric procedures, and they both restrict food intake and the amount of calories and nutrients the body absorbs.

The two major combined operations are:

• Roux-en-Y gastric bypass (RGB). The surgeon first creates a small stomach pouch that is sealed off from the rest of the stomach, restricting food intake. Then, the amount of calories and nutrients the body absorbs is reduced by attaching a Y-shaped section of the small intestine to the pouch. This allows food to bypass the lower stomach, the duodenum and the first portion of the jejunum. In some cases, the gallbladder may be removed (cholecystectomy) to prevent the gallstones that sometimes result from rapid weight loss. The development of gallstones after bariatric surgery can sometimes be prevented with medication.
  

  

• Biliopancreatic diversion (BPD). More complicated than RGB, it involves removing the lower portion of the stomach and connecting the small pouch that remains to the final segment of the small intestine. In this procedure, the duodenum and jejunum are completely bypassed. Although this procedure leads to weight loss, it is not performed as frequently as an RGB because there is a higher risk of nutritional deficiency.

All of these procedures have pros and cons. Restrictive operations are easier to perform and are usually safer than malabsorptive procedures. They can also be reversed and do not create major nutritional deficiencies. However, patients tend to lose less weight after these procedures than after malabsorptive operations, and they are less likely to keep the weight off over long periods of time. Patients may also experience vomiting whenever they eat too much, and the band and tubing are subject to slippage and wear, which may result in the need for a second surgery. In rare cases, infection and bleeding may follow AGB.

Patients who have a combined restrictive/malabsorptive operation tend to lose more weight than those who have purely restrictive operations. In addition, they typically lose weight more quickly and keep more of it off for longer periods of time. The fact that these patients lose more weight may offer added benefits for those with health problems such as high blood pressure (hypertension), sleep apnea, type 2 diabetes and osteoarthritis.

However, these procedures are more difficult to perform than purely restrictive operations and are more likely to cause long-term nutritional deficiencies in patients, particularly iron and calcium deficiencies. This means that many patients (especially menstruating women) are likely to develop anemia. All bariatric surgery patients are more likely to develop osteoporosis and other bone diseases. Nutritional supplements may help prevent these disorders. Patients who have RGB or BPD surgery may also suffer from dumping syndrome, which occurs when a meal high in simple carbohydrates (e.g., bread) moves too quickly through the small intestine, leading to nausea, bloating, abdominal pain, weakness, sweating, faintness and diarrhea. Patients are also at risk for developing an infection or abdominal hernia.

Patients usually are urged not to have bariatric surgery unless the health risks of obesity are greater than the risks of having the surgery. Deaths and other illness have occurred as a result of these surgeries. However, the risk of death or infection is relatively low, according to the American Obesity Association. Research from the International Bariatric Surgery Registry (IBSR) show that death within 30 days of surgery occurs in less than one-quarter of 1 percent (0.17 percent) of all vertical banded gastroplasty and Roux-en-Y gastric bypass surgeries.