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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.
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 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.
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How Does Surgery Promote Weight Loss?
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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.
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What Are the Surgical Options?
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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 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).
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 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. |
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 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.
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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.
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 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.
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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.
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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
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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. |
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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
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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.
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Medical Costs
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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.
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Is the Surgery for You?
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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:
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a BMI of 40 or more
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a life-threatening obesity-related health problem such as diabetes,
severe sleep apnea, or heart disease and a BMI of 35 or more
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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.
Are 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?
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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.
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Additional Reading
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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.
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Additional Resource
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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
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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.
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U.S. DEPARTMENT OF HEALTH AND HUMAN
SERVICES
National Institutes of HealthNIH Publication No. 01-4006
December 2001
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