Severe obesity is a chronic condition that is very difficult to treat. For some people, surgery to promote weight loss by restricting food intake or interrupting digestive processes is an option. A body mass index (BMI) above 40--which means about 100 pounds overweight for men and about 80 pounds for women--indicates that a person is severely obese and therefore a candidate for surgery. Surgery also may be an option for people with a BMI between 35 and 40 who suffer from life-threatening cardiopulmonary problems (for example, severe sleep apnea or obesity-related heart disease) or diabetes. However, as in other treatments for obesity, successful results depend mainly on motivation and behavior.

The normal digestive process
Normally, as food moves along the digestive tract, appropriate digestive juices and enzymes arrive at the right place at the right time to digest and absorb calories and nutrients. After we chew and swallow our food, it moves down the esophagus to the stomach, where a strong acid continues the digestive process. The stomach can hold about 3 pints of food at one time. When the stomach contents move to the duodenum, the first segment of the small intestine, bile and pancreatic juices speed up digestion. Most of the iron and calcium in the foods we eat is absorbed in the duodenum. The jejunum and ileum, the remaining two segments of the nearly 20 feet of small intestine, complete the absorption of almost all calories and nutrients. The food particles that cannot be digested in the small intestine are stored in the large intestine until eliminated.

How does surgery promote weight loss?
The concept of gastric 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, caused weight loss through 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.

Surgeons now use techniques that produce weight loss primarily by limiting how much the stomach can hold. These restrictive procedures are often combined with modified gastric bypass procedures that somewhat limit calorie and nutrient absorption and require new eating habits.

Two ways that surgical procedures promote weight loss are:

1.  By decreasing food intake (restriction). Gastric banding, gastric bypass, and vertical-banded gastroplasty are surgeries that limit the amount of food the stomach can hold by closing off or removing parts of the stomach. These operations also delay emptying of the stomach (gastric pouch).
2.  By causing food to be poorly digested and absorbed (malabsorption). In the gastric bypass procedures, a surgeon makes a direct connection from the stomach to a lower segment of the small intestine, bypassing the duodenum, and some of the jejunum.

Restriction operations
Restriction operations are the surgeries most often used for producing weight loss. Food intake is restricted by creating a small pouch at the top of the stomach where the food enters from the esophagus. The pouch initially holds about 1 ounce of food and expands to 2-3 ounces with time. The pouch's lower outlet usually has a diameter of about 1/4 inch. The small outlet delays the emptying of food from the pouch and causes a feeling of fullness.

After this type of operation, the person usually can eat only a half to a whole cup of food without causing discomfort or nausea. Fluids are limited to small sips and should not be included with meals since the new smaller stomach may not be large enough to hold fluid and food at the same time. Also, food has to be well chewed. For most people, the ability to eat a large amount of food at one time is lost. Therefore, it is necessary to eat several (5-6) small meals throughout the day to get enough nutrients.

Restrictive operations lead to weight loss in almost all patients. However, weight regain does occur in some patients. About 30 percent of persons undergoing vertical banded gastroplasty achieve normal weight, and about 80 percent achieve some degree of weight loss. However, some patients are unable to adjust their eating habits and fail to lose the desired weight. In all weight-loss operations, successful results depend on your motivation and behaviors.

Restriction operations for obesity include gastric banding and vertical banded gastroplasty. Both operations serve only to restrict food intake. They do not interfere with the normal digestive process.

Laparoscopic gastric banding: During this procedure, surgeons typically use laparoscopic techniques and instruments to implant an inflatable silicone band into the patient's abdomen. Similar to a wristwatch, the band is fastened around the upper stomach to create a new, tiny pouch that limits and controls the amount of food consumed. The band also creates a small outlet that slows the emptying process into the stomach and the intestines allowing the patient to experience an earlier sensation of fullness and increased satisfied with smaller amounts of food. This ultimately results in weight loss. 

The LAP BAND® patient can expect a reduced hospital stay of one to two days; in some instances there may be an increased stay if the surgery required an abdominal incision or complications occurred. Patients may resume normal activities in one to two weeks; again, expect a delay if there is an abdominal incision or complications occurred.

The LAP BAND® procedure requires no cutting or stapling of the stomach and bowel and is considered the least invasive weight loss surgery available. The band is also adjustable and can be modified by inflating or deflating the inner surface with saline solution. The surgeon can control the amount of saline in the band using a fine needle through the skin. The adjustments are made in the surgeon's exam room and patients have noted minimal discomfort. Finally, should the band need to be removed, the stomach will return to its original form and function.

Vertical banded gastroplasty (VBG): In this procedure, the surgeon uses staples and a plastic band to create a smaller stomach pouch. Patients are unable to eat large quantities of food and do notice a feeling of fullness. Although this is a quick procedure with fewer complications, patients have less weight loss after several years. This procedure is not offered at the Clinic.

Risks of VBG include erosion of the band, breakdown of the staple line, and, in a small number of cases, leakage of stomach juices into the abdomen. The latter requires an emergency operation. In a very small number of cases (less than 1 percent) infection or death from complications can occur.

Gastric bypass operations
These types of operations combine the creation of a small stomach pouch to restrict food intake and construction of bypasses of the duodenum and other segments of the small intestine to cause malabsorption.

Roux-en-Y gastric bypass (RGB): This operation is the most common gastric bypass procedure. First, a small stomach pouch is created by stapling or by vertical banding. This causes restriction in food intake. Next, a Y-shaped section of the small intestine is attached to the pouch to allow food to bypass the duodenum as well as the first portion of the jejunum. This causes reduced calorie and nutrient absorption.

Extensive gastric bypass (biliopancreatic diversion): In this more complicated gastric bypass operation, portions of the stomach are removed. The small pouch that remains is connected directly to the final segment of the small intestine, thus completely bypassing both the duodenum and jejunum. Although this procedure successfully promotes weight loss, it is not widely used because of the high risk for nutritional deficiencies. This procedure is not offered at the Cleveland Clinic.

Gastric bypass operations that cause malabsorption and restrict food intake produce more weight loss than restriction operations, which only decrease food intake. Patients who have bypass operations generally lose two-thirds of their excess weight within 2 years.

The risks for pouch stretching, band erosion, breakdown of staple lines, and leakage of stomach contents into the abdomen are about the same for gastric bypass as for vertical banded gastroplasty. However, because gastric bypass operations cause food to skip the duodenum, where most iron and calcium are absorbed, risks for nutritional deficiencies are higher in these procedures. Anemia may result from malabsorption of vitamin B12 and iron in menstruating women, and decreased absorption of calcium may bring on osteoporosis and metabolic bone disease. Patients are required to take nutritional supplements that usually prevent these deficiencies.

Explore benefits and risks
Surgery to produce weight loss is a serious undertaking. Each individual should clearly understand what the proposed operation involves. Persons considered for surgery must be carefully evaluated. Studies are performed to assess the health of the patient's cardiovascular and endocrine systems. A psychological evaluation is considered essential by most physicians to determine a potential patient's response to weight loss and change in body image. Nutritional counseling is also a must before surgery. Patients and physicians should carefully consider the following benefits and risks:

• Immediately following surgery, most patients lose weight rapidly and continue to do so until 18 to 24 months after the procedure. Although most patients then start to regain some of their lost weight, few regain it all.
• Surgery improves most obesity-related conditions. For example, in one study, blood sugar levels of most obese patients with diabetes returned to normal after surgery. Nearly all patients whose blood sugar levels did not return to normal were older or had diabetes for a long time.

• A common risk of restrictive operations is vomiting caused by the small stomach being overly stretched by food particles that have not been chewed well.
• Gastric bypass operations also may cause "dumping syndrome," whereby stomach contents move too rapidly through the small intestine. Symptoms include nausea, weakness, sweating, faintness, and, occasionally, diarrhea after eating, as well as the inability to eat sweets without becoming so weak and sweaty that the patient must lie down until the symptoms pass.
• The more extensive the bypass operation, the greater is the risk for complications and nutritional deficiencies. Patients with extensive bypasses of the normal digestive process require not only close monitoring, but also life-long use of special foods and medications.
• Ten to 20 percent of patients who have weight-loss operations require follow-up operations to correct complications. Abdominal hernias (ruptures) are the most common complications requiring follow-up surgery. Less common complications include breakdown of the staple line and stretched stomach outlets.
• More than one-third of obese patients who have gastric surgery develop gallstones. Gallstones are clumps of cholesterol and other matter that form in the gallbladder. During rapid or substantial weight loss a person's risk of developing gallstones is increased. Gallstones can be prevented with supplemental bile salts taken for the first 6 months after surgery.
• Nearly 30 percent of patients who have weight-loss surgery develop nutritional deficiencies such as anemia, osteoporosis, and metabolic bone disease. These deficiencies can be avoided if vitamin and mineral intakes are maintained.
• Women of childbearing age should avoid pregnancy until their weight becomes stable because rapid weight loss and nutritional deficiencies can harm a developing fetus.
• Common side effects/discomforts include: nausea, vomiting, bloating, diarrhea, excessive sweating, increased gas and dizziness.

Is the surgery for you?
For patients who remain severely obese after nonsurgical approaches to weight loss have failed, or for patients who have an obesity-related disease, surgery may be an appropriate treatment option. But for other patients, greater efforts toward weight control, such as changes in eating habits, lifestyle changes, and increasing physical activity, may be more appropriate. Answers to the following questions may help in your discussion with your health care provider about surgery for weight loss.

• Unlikely to lose weight successfully with (further) nonsurgical measures?
• Well informed about the surgical procedure and the effects of treatment?
• Determined to lose weight and improve your health?
• Aware of how your life may change after the operation (adjustment to the side effects of the surgery, including dramatically different eating habits)?
• Aware of the potential for serious complications, the associated dietary restrictions, and the occasional failures?
• Committed to life-long medical follow-up?

• Have a BMI of 40 or more?
• Have an obesity-related physical problem (such as body size that interferes with employment, walking, or family function)?
• Have high-risk, obesity-related health problems (such as severe sleep apnea or obesity-related heart disease)?

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This information is provided by the Cleveland Clinic and is not intended to replace the medical advice of your doctor or health care provider. Please consult your health care provider for advice about a specific medical condition. For additional written health information, please contact the Health Information Center at the Cleveland Clinic (216) 444-3771 or toll-free (800) 223-2273 extension 43771 or visit www.clevelandclinic.org/health/.

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