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National Institute of Diabetes and

Digestive and Kidney Diseases

NATIONAL INSTITUTES OF HEALTH

WIN Weight-control Information Network

Gastrointestinal

Surgery for

Severe Obesity

You may be a candidate

for surgery if you have:

■ a body mass index

(BMI) of 40 or more—

about 100 pounds

overweight for men

and 80 pounds for

women (see BMI

chart on page 2)

■ a BMI between 35 and

39.9 and a serious

obesity-related health

problem such as type 2

diabetes, heart

disease, or severe

sleep apnea (when

breathing stops for

short periods during

sleep)

■ an understanding of

the operation and the

lifestyle changes you

will need to make.

evere obesity is a chronic condition that is difficult to treat through

diet and exercise alone. Gastrointestinal surgery is an option for

people who are severely obese and cannot lose weight by traditional

means or who suffer from serious obesity-related health problems. The

operation 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.

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 can be divided into three types:

restrictive, malabsorptive, and combined restrictive/malabsorptive.

Restrictive operations limit food intake by creating a narrow passage

from the upper part of the stomach into the larger lower part, reducing

the amount of food the stomach can hold and slowing the passage of food

through the stomach. Malabsorptive operations do not limit food intake,

S
2

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.

* Without shoes

** Without clothes

Table 1

but instead exclude most of the small intestine from the digestive tract so

fewer calories and nutrients are absorbed. Malabsorptive operations, also

called intestinal bypasses, are no longer recommended because they result

in severe nutritional deficiencies. Combined operations use stomach

restriction and a partial bypass of the small intestine.

What Are the Surgical Options?

There are several types of restrictive and combined operations. Each one

has its own benefits and risks.

Restrictive Operations

Purely restrictive operations only limit food intake and do not interfere

with the normal digestive process. To perform the operation, doctors

create a small pouch at the top of the stomach where food enters from the

esophagus. At first, the pouch holds about 1 ounce of food and later may

stretch to 2-3 ounces. The lower outlet of the pouch is usually about 1⁄2

inch in diameter or smaller. This small outlet delays the emptying of food

from the pouch into the larger part of the stomach and causes a feeling of

fullness.

After the operation, patients can no longer eat large amounts of food at

one time. Most patients can eat about 1⁄2 to 1 cup of food without

Malabsorptive operations,

also called intestinal

bypasses, are no longer

recommended because they

result in severe nutritional

deficiencies.
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Figure 3

Vertical banded gastroplasty

discomfort or nausea, but the food has to be soft, moist, and well chewed.

Patients who undergo restrictive procedures generally are not able to eat as

much as those who have combined operations.

Purely 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

silicone rubber is placed around the stomach near its upper end, creating a small pouch and a narrow passage into the rest of the stomach

(figure 2). The band is then inflated with a salt solution through a tube

that connects the band to an access port placed under the skin. 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 uses both a band and staples to

create a small stomach pouch, as illustrated in figure 3. Once the most

common restrictive operation, VBG is not often used today.

Advantages: Restrictive operations are easier to perform and are generally

safer than malabsorptive operations. AGB is usually done via laparoscopy,

which uses smaller incisions, creates less tissue damage, and involves

shorter operating time and hospital stays than open procedures. (See page

5 for more information on laparoscopy.) Restrictive operations can be

reversed if necessary, and result in few nutritional deficiencies.

Disadvantages: Patients who undergo restrictive operations generally lose

less weight than patients who have malabsorptive operations, and are less

likely to maintain weight loss over the long term. Patients generally lose

about half of their excess body weight in the first year after restrictive

procedures. However, in the first 3 to 5 years after VBG patients may

regain some of the weight they lost. By 10 years, as few as 20 percent of

patients have kept the weight off. (Although there is less information

about long-term results with AGB, there is some evidence that weight loss

results are better than with VBG.) Some patients regain weight by eating

high-calorie soft foods that easily pass through the opening to the

stomach. Others are unable to change their eating habits and do not lose

much weight to begin with. Successful results depend on the patient’s

willingness to adopt a long-term plan of healthy eating and regular

physical activity.

Risks: One of the most common risks of restrictive operations is vomiting,

which occurs when the patient eats too much or the narrow passage into

the larger part of the stomach is blocked. Another is slippage or wearing

away of the band. A common risk of AGB is breaks in the tubing between

the band and the access port. This can cause the salt solution to leak,

requiring another operation to repair. Some patients experience infections

and bleeding, but this is much less common than other risks. Between 15

and 20 percent of VBG patients may have to undergo a second operation

for a problem related to the procedure. Although restrictive operations are

the safest of the bariatric procedures, they still carry risk—in less than 1

percent of all cases, complications can result in death.

Figure 2

Adjustable gastric banding

Esophagus

Small Stomach

Pouch

Band

Duodenum

Stomach

Esophagus

Small Stomach

Pouch

Staples

Band

Duodenum

Stomach
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Esophagus

Small Pouch

Staples

Duodenum

Stomach

Figure 6

BPD/duodenal switch

Combined Restrictive/Malabsorptive Operations

Combined operations are the most common bariatric procedures. 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 combined procedure in the

United States. First, the surgeon creates a small stomach pouch 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 reduces

the amount of calories and nutrients the body absorbs. Rarely, a cholecystectomy (gall bladder removal) is performed to avoid the gallstones

that may result from rapid weight loss. More commonly, patients take

medication after the operation to dissolve gallstones. (See WIN’s fact

sheet Dieting and Gallstones for more information.)

■ Biliopancreatic diversion (BPD). In this more complicated combined

operation, the lower portion of the stomach is 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 leads to weight loss, it is used less

often than other types of operations 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. The larger stomach allows patients to eat more

after the surgery than patients who have other types of procedures.

Advantages: Most patients lose weight quickly and continue to lose for

18 to 24 months after the procedure. With the Roux-en-Y gastric bypass,

many patients maintain a weight loss of 60 to 70 percent of their excess

weight for 10 years or more. With BPD, most studies report an average

weight loss of 75 to 80 percent of excess weight. Because combined

operations result in greater weight loss than restrictive operations, they

may also be more effective in improving the health problems associated

with severe obesity, such as hypertension (high blood pressure), sleep

apnea, type 2 diabetes, and osteoarthritis.

Disadvantages: Combined procedures are more difficult to perform than

the restrictive procedures. They are also more likely to result in long-term

nutritional deficiencies. This is because the operation 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 related bone diseases. Patients must take

nutritional supplements that usually prevent these deficiencies. Patients

who have the biliopancreatic diversion procedure must also take fatFigure 4

Roux-en-Y gastric bypass

Figure 5

Extensive gastric bypass

Remainder of Partially

Removed Pouch

Ileum

Jejunum

Duodenum

Colon

Gallbladder

Removed

Digestive

Loop

Duodenal

Switch

Common

Loop

Partially

Resected

Stomach

Bilo-Pancreatic

Loop
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soluble (dissolved by fat) vitamins A, D, E, and K supplements, and

require life-long use of special foods and medications.

RGB and BPD operations may also cause “dumping syndrome,” an

unpleasant reaction that can occur after a meal high in simple

carbohydrates, which contain sugars that are rapidly absorbed by the body.

Stomach contents move too quickly through the small intestine, causing

symptoms such as nausea, bloating, abdominal pain, 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.

Risks: In addition to risks associated with restrictive procedures such as

infection, combined operations are more likely to lead to complications.

The risk of death associated with these types of procedures is lower for the

gastric bypass (less than 1 percent of patients) than for the biliopancreatic

diversion with duodenal switch (2.5 to 5 percent). Combined operations

carry a greater risk than restrictive operations for abdominal hernias (up

to 28 percent), which require a follow-up operation to correct. The risk of

hernia, however, is lower (about 3 percent) when laparoscopic techniques

are used.

Laparoscopic Bariatric Surgery

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 super-obese (more than 350 pounds) or have had previous abdominal

operations may not be good candidates for laparoscopy, however.

Adjustable gastric banding is routinely performed via laparoscopy.

This technique is often used for Roux-en-Y gastric bypass, and although

less common, biliopancreatirc diversion can also be performed

laparoscopically. The small incisions result in less blood loss, shorter

hospitalization, a faster recovery, and fewer complications than open

operations. However, combined laparoscopic procedures are more difficult

to perform than open procedures and can create serious problems if done

incorrectly.

Bariatric Surgery for Adolescents

With rates of overweight among youth on the rise, bariatric surgery is

sometimes considered as a treatment option for adolescents who are

severely overweight. However, there are many concerns about the longterm effects of this type of operation on adolescents’ developing bodies

and minds. Experts in pediatric overweight and bariatric surgery

recommend that surgical treatment only be considered when adolescents

have tried for at least 6 months to lose weight and have not been

successful. Candidates should be severely overweight (BMI of 40 or

more), have reached their adult height (usually 13 or older for girls, 15 or

Because combined

operations result in greater

weight loss than restrictive

operations, they may also be

more effective in improving

the health problems

associated with severe

obesity, such as hypertension

(high blood pressure), sleep

apnea, type 2 diabetes, and

osteoarthritis.
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older for boys), and have serious weight-related health problems such as

type 2 diabetes or heart disease. In addition, potential patients and their

parents should be evaluated to see how emotionally prepared they are for

the operation and the lifestyle changes they will need to make. Patients

should also be referred to a team of experts in adolescent medicine and

bariatric surgery who are qualified to meet their unique needs.

Medical Costs

Bariatric procedures cost from $20,000 to $35,000. Medical insurance

coverage varies by state and insurance provider. If you are considering

bariatric surgery, contact your regional Medicare or Medicaid office or

insurance plan to find out if the procedure is covered.

Is Surgery for You?

Bariatric 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. Surgery to produce weight loss is a serious

undertaking. Anyone thinking about undergoing this type of operation

should understand what it involves. Answers to the following questions

may help you decide whether weight-loss surgery is right for you.

Are you:

■ unlikely to lose weight or keep weight off long-term with 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 operation, including the need to chew food well

and inability to eat large meals)?

■ aware of the potential for serious complications, dietary restrictions,

and occasional failures?

■ committed to lifelong medical follow-up and vitamin/mineral

supplementation?

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.

Bariatric 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.
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Research

In 2003, the National Institute of Diabetes and Digestive and Kidney

Diseases (NIDDK) of the National Institutes of Health (NIH) formed a

partnership with researchers called the Longitudinal Assessment of

Bariatric Surgery, or LABS. LABS researchers are experts in bariatric

surgery, obesity research, internal medicine, behavioral science, and

related fields. Their mission is to plan and conduct studies that will lead

to better understanding of bariatric surgery and its impact on the health

and well-being of patients with extreme obesity. For more information on

LABS, visit www.niddklabs.org.

Additional Reading

Active at Any Size. NIH Publication No. 04-4352. This booklet explains

how physical activity can improve your health and describes different

types of activities that very large people can do safely. Available from

WIN.

Dieting and Gallstones. NIH Publication No. 02-3677. This fact sheet

explains what gallstones are, how they are formed, and the roles obesity

and rapid weight loss play in the development of gallstones. Available

from WIN.

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. 04-3700. 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

100 SW 75th Street, Suite 201

Gainesville, FL 32607

Phone: (352) 331-4900

Fax: (352) 331-4975

Website: www.asbs.org

Success is possible only with

maximum cooperation and

commitment to behavioral

change and medical followup—and this cooperation

and commitment must be

carried out for the rest of

your life.
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U.S. DEPARTMENT OF HEALTH AND HUMAN SERVICES

National Institutes of Health

NIH Publication No. 04-4006

December 2004

Weight-control

Information

Network

1 WIN WAY

BETHESDA

MD 20892-3665

Phone: (202) 828-1025

Toll-free number:

1-877-946-4627

FAX: (202) 828-1028

Email:

WIN@info.niddk.nih.gov

Internet:

www.win.niddk.nih.gov

This publication is not copyrighted. WIN

encourages users of this fact sheet to duplicate

and distribute as many copies as desired.

This fact sheet is also available at

www.win.niddk.nih.gov

The Weight-control Information

Network (WIN) is a national

information 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, sciencebased health information on weight

control, obesity, physical activity, and

related nutritional issues.

Publications produced by WIN are

reviewed by both NIDDK scientists

and outside experts. This fact sheet

was also reviewed by Walter Pories,

M.D., FACS, Professor of Surgery

and Biochemistry, Brody School of

Medicine at East Carolina University;

David Flum, M.D., Clinical Instructor,

Department of Surgery, University

of Washington School of Medicine;

and Thomas Inge, M.D., Ph.D., FACS,

FAAP, Assistant Professor of Surgery

and Pediatrics and Surgical Director,

Comprehensive Weight Management

Center, Cincinnati Children’s Hospital

Medical Center.