Severe obesity is a chronic condition that is difficult to treat through diet and exercise alone. Gastrointestinal 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.
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 (see table 1 for a BMI conversion chart). 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.
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.
The Normal Digestive Process
Normally,
as food moves along the digestive tract, digestive juices and enzymes
digest and absorb calories and nutrients (see figure 1). 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
juice 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?
Gastrointestinal surgery for obesity, also called bariatric 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.
Table 1. Body Mass Index
Body
Mass Index. Find your weight on the bottom of the graph. Go straight
up from that point until you come to the line that matches your height.
Then look to find your weight group.
What Are the Surgical Options?
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 ¾ 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 ¾ 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).
Adjustable
gastric banding.
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 (figure 2).
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.
Vertical
banded gastroplasty. VBG has been the most common restrictive
operation for weight control. As figure 3 illustrates, both a band and
staples are used to create a small stomach pouch.
Although restrictive operations lead to weight loss in almost all patients, they are less successful than malabsorptive operations in achieving substantial, long-term weight loss. About 30 percent of those who undergo VBG achieve normal weight, and about 80 percent achieve some degree of weight loss. Some patients regain weight. Others are unable to adjust their eating habits and fail to lose the desired weight. Successful results depend on the patient’s willingness to adopt a long-term plan of healthy eating and regular physical activity.
A common risk of restrictive operations is vomiting, which is caused when the small stomach is overly stretched by food particles that have not been chewed well. Band slippage and saline leakage have been reported after AGB. 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 an emergency operation. In less than 1 percent of all cases, infection or death from complications may occur.
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.
Roux-en-Y
gastric bypass (RGB). This operation, illustrated in figure
4, is the most common and successful malabsorptive surgery. First, a
small stomach pouch is created to restrict food intake. Next, a Y-shaped
section of the small intestine is attached to the pouch to allow food
to bypass the lower stomach, the duodenum (the first segment of the
small intestine), and the first portion of the jejunum (the second segment
of the small intestine). This bypass reduces the amount of calories
and nutrients the body absorbs.
Biliopancreatic diversion (BPD). In this more complicated
malabsorptive operation, portions of the stomach are removed (see figure
5). 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 for nutritional deficiencies. A variation of BPD includes
a “duodenal switch” (see figure 6), 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.
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.
In addition to the risks of restrictive surgeries, malabsorptive operations also carry greater risk for nutritional deficiencies. This is because the procedure causes food to bypass the duodenum and jejunum, where most iron and calcium are absorbed. Menstruating women may develop anemia because not enough vitamin B12 and iron are absorbed. Decreased absorption of calcium may also bring on osteoporosis and metabolic bone disease. Patients are required to take nutritional supplements that usually prevent these deficiencies. Patients who have the biliopancreatic diversion surgery must also take fat-soluble (dissolved by fat) vitamins A, D, E, and K supplements.
RGB and BPD operations may also cause “dumping syndrome.” This means that stomach contents move too rapidly through the small intestine. Symptoms include nausea, weakness, sweating, faintness, and sometimes diarrhea after eating. Because the duodenal switch operation keeps the pyloric valve intact, it may reduce the likelihood of dumping syndrome.
The more extensive the bypass, the greater the risk for complications and nutritional deficiencies. Patients with extensive bypasses of the normal digestive process require close monitoring and life-long use of special foods, supplements, and medications.
Explore Benefits and Risks
Surgery to produce weight loss is a serious undertaking. Anyone thinking about surgery should understand what the operation involves. Patients and physicians should carefully consider the following benefits and risks:
Benefits
- Right after surgery, most patients lose weight quickly and continue to lose for 18 to 24 months after the procedure. Although most patients regain 5 to 10 percent of the weight they lost, many maintain a long-term weight loss of about 100 pounds.
- Surgery improves most obesity-related conditions. For example, in one study blood sugar levels of 83 percent of 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 lived with diabetes for a long time.
Risks
-
Ten to 20 percent of patients who have weight-loss surgery require follow-up operations to correct complications. Abdominal hernia was the most common complication requiring follow-up surgery, but laparoscopic techniques seem to have solved this problem. In laparoscopy, the surgeon makes one or more small incisions through which slender surgical instruments are passed. This technique eliminates the need for a large incision and creates less tissue damage. Patients who are superobese (>350 pounds) or have had previous abdominal surgery may not be good candidates for laparoscopy, however. Less common complications include breakdown of the staple line and stretched stomach outlets.
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Some obese patients who have weight-loss 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 increases. Taking supplemental bile salts for the first 6 months after surgery can prevent gallstones.
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Nearly 30 percent of patients who have weight-loss surgery develop nutritional deficiencies such as anemia, osteoporosis, and metabolic bone disease. These deficiencies usually can be avoided if vitamin and mineral intakes are high enough.
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Women of childbearing age should avoid pregnancy until their weight becomes stable because rapid weight loss and nutritional deficiencies can harm a developing fetus.
Medical Costs
Gastrointestinal surgery costs about $15,000. Medical insurance coverage varies by state and insurance provider. If you are considering gastrointestinal surgery, contact your regional Medicare or Medicaid office or insurance plan to find out if the procedure is covered.
Gastrointestinal surgery may be the next step for people who remain severely obese after trying nonsurgical approaches, or for people who have an obesity-related disease. Candidates for surgery have:
- a BMI of 40 or more
- a life-threatening obesity-related health problem such as diabetes, severe sleep apnea, or heart disease and a BMI of 35 or more
- obesity-related physical problems that interfere with employment, walking, or family function.
If you fit the profile for surgery, answers to the following questions may help you decide whether weight-loss surgery is appropriate for you.
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unlikely to lose weight successfully with nonsurgical measures?
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well informed about the surgical procedure and the effects of treatment?
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determined to lose weight and improve your health?
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aware of how your life may change after the operation (adjustment to the side effects of the surgery, including the need to chew well and inability to eat large meals)?
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aware of the potential for serious complications, dietary restrictions, and occasional failures?
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committed to lifelong medical follow-up?
Remember: There are no guarantees for any method, including surgery, to produce and maintain weight loss. Success is possible only with maximum cooperation and commitment to behavioral change and medical follow-up—and this cooperation and commitment must be carried out for the rest of your life.
Additional Reading
Gastrointestinal Surgery for Severe Obesity. Consensus Statement, NIH Consensus Development Conference, March 25-27, 1991; Public Health Service, National Institutes of Health, Office of Medical Applications of Research. This publication, written for health professionals, summarizes the findings of a conference discussing treatments for severe obesity. Available from WIN.
Weight Loss for Life. NIH Publication No. 00-3700. This booklet describes how we lose weight, healthy eating habits, the importance of physical activity, and behavior change. Available from WIN.
Additional Resource
American
Society for Bariatric Surgery
140 NW 75th Drive, Suite C
Gainesville, FL 32607
Phone: (352) 331-4900
Fax: (352) 331-4975
Website: www.asbs.org
Weight-control Information Network
1 WIN WAY
BETHESDA, MD 20892-3665
Phone: (202) 828-1025
FAX: (202) 828-1028
Email: WIN@info.niddk.nih.gov
Internet: www.niddk.nih.gov/health/nutrit/nutrit.htm
Toll-free number: 1-877-946-4627
E-mail: win@info.niddk.nih.gov
The Weight-control Information Network is a service of the National Institute of Diabetes and Digestive and Kidney Diseases of the National Institutes of Health, which is the Federal Government’s lead agency responsible for biomedical research on nutrition and obesity. Authorized by Congress (Public Law 103-43), WIN provides the general public, health professionals, the media, and Congress with up-to-date, science-based health information on weight control, obesity, physical activity, and related nutritional issues.
WIN answers inquiries, develops and distributes publications, and works closely with professional and patient organizations and Government agencies to coordinate resources about weight control and related issues.
Publications produced by WIN are carefully reviewed by both NIDDK scientists and outside experts. This fact sheet was also reviewed by Patricia Choban, M.D., Adjunct Professor of Human Nutrition and Food Management, Ohio State University and Walter Pories, M.D., Professor of Surgery and Biochemistry, Brody School of Medicine at East Carolina University.
This e-text is not copyrighted. The clearinghouse encourages users of this e-pub to duplicate and distribute as many copies as desired.
U.S. DEPARTMENT OF HEALTH AND HUMAN SERVICES
National Institutes of Health
NIH Publication No. 01-4006
December 2001
