Gastric Bypass Surgery

TV personality Star Jones lost 160 pounds in three years after gastric bypass surgery. See more food proportion pictures.
Jennifer Graylock/Associated Press

Between 1980 and 2004, the rate of obesity more than doubled in the United States, and the numbers continue to rise. In fact, obesity is a leading cause of preventable death in the U.S., second only to tobacco use. While some people may view obesity as a cosmetic problem, it carries serious health risks. Those suffering from obesity have a much higher risk for life-threatening ailments, including high blood pressure, diabetes, stroke and heart problems.

The challenge, of course, is losing the weight, and many obese patients cannot achieve this through simple diet, exercise or medication. After exhausting all of these options, many people consider weight-loss surgery. There are several types of weight-loss surgery, but gastric bypass surgery is the most common. Doctors perform an estimated 140,000 gastric bypass surgeries in the United States every year [Source: American Society for Bariatric Surgery].


People usually lose more weight through gastric bypass surgery than through other forms of weight-loss surgery -- on average, 60 percent of their excess weight. In plain numbers, this means a patient who has 200 extra pounds of weight will lose approximately 120 pounds. These results are impressive, and unlike with other weight-loss surgeries, weight loss resulting from a gastric bypass surgery usually remains lost for more than 10 years.

While the majority of patients undergoing weight-loss surgery will experience significant weight loss, it is important to note that these surgeries are not a quick and easy way to lose weight. Instead, patients lose weight over the span of months or years. They must relearn how to eat the right portions of the right foods and to eat for the right reasons.

In this article, we will look at what makes a good candidate for gastric bypass surgery, how the surgery is performed, how it works, the risks and how to ensure a rapid recovery.­­


Who is a Good Candidate for Gastric Bypass Surgery?

Your body mass index takes into account your weight and height.
Julia Freeman-Woolpert, ­SXC

Not everyone suffering from obesity is eligible for weight-loss surgery. While guidelines can vary from surgeon to surgeon, the National Institutes of Health (NIH) has set a few standard criteria for screening patients for surgery. Those patients whose body mass index (BMI) is between 35 and 40 can be considered if they are also suffering from a complication caused by their obesity, such as diabetes. For patients with a BMI of more than 40, no complication is required for approval.

Beyond the BMI qualifications, patients must have been obese for more than three years and have attempted to lose weight through diet, exercise and medications without success. Because weight gain is often a result of psychological factors, patients must have a psychiatrist's clearance before they can have the surgery. Psychological criteria include assessments for any self-destructive behaviors, depression or substance abuse. While strict, these criteria are essential in order to ensure the success of the surgery and, ultimately, the weight loss.


While doctors do not typically perform gastric bypass surgery on adolescents, certain situations may make surgery necessary. Doctors may consider surgery for adolescents who have a BMI of 40 or more, have tried to lose weight for at least six months, have severe complications as a result of their obesity and have reached their adult height. Boys usually reach adult height around the age of 15, girls around age 13.

The Risks

Gastric bypass surgery has some of the same risks as other surgeries, including infection of the incision site, excessive blood loss and blood clots. The procedure also has its own specific risks, including the development of gallstones, stomach leaks, hernias and bowel blockages. In some cases, the newly made connection between the stomach and the intestines can tighten. This narrowing often results in nausea and vomiting directly after a meal.

The most common complication is malnutrition. Because food travels directly from the stomach pouch to the middle of the small intestine, the patient absorbs fewer calories and fewer nutrients from food. This can often result in a lack of iron, calcium or vitamin B12 in the body, leading to anemia and osteoporosis. Because this risk is dangerous, doctors require most patients to keep a journal of what and how much they eat each day. This food journal allows doctors and nutritionists to make sure the body is absorbing enough of the right nutrients.

Some patients can also suffer from what is known as dumping syndrome. This complication is a result of food moving too quickly through the body. It can cause the patient to feel nauseated, sweaty and faint. Eating sweets may cause extreme weakness and diarrhea. Sugar tends to be especially irritating due to its high osmolarity. This is a measure of osmotic pressure, which relates to the speed at which fluids travel through a membrane. When these foods arrive in the small intestine, they draw lots of fluid into the intestine along with them. The intestine tries to move them out of the body quickly in an effort to regain balance of intestinal fluids, which is why the cramping and diarrhea can happen. Patients who have undergone gastric bypass surgery should stick to natural sugars like those found in fruits, which do not usually cause dumping syndrome.

Other complications can occur if the patient does not stick to the required diet after the operation. Eating too much food can result in the staples pulling loose and the stomach returning to its original size. Replacing the staples requires an additional surgery.

Finally, there is a risk of death with gastric bypass surgery. The risk varies with the age and overall health of each patient. In general, the likelihood of death ranges from 0.3 percent to 1.0 percent.

Now we'll take a look at what happens before the surgery.


Before the Surgery

Smoking is a no-no for those about to undergo ­gastric bypass surgery.
Image courtesy of the South Carolina Office of Human Resources

Before a gastric bypass surgery, patients need to make several changes to their lifestyle. Doctors may recommend smaller meal portions and restrict some foods. Doctors may also encourage smokers to quit or to reduce the number of cigarettes they smoke. Smokers should quit at least two weeks before surgery, but six to eight weeks prior to surgery is ideal. Quitting smoking is important because smokers heal more slowly than nonsmokers, which can result in complications after the surgery, including infection. In addition, smokers are at a higher risk for breathing problems while under anesthesia.

While support groups are not a requirement, patients do need to prove that they have a strong support system before being seriously considered for surgery. This step of the screening process is essential because many obese patients eat for emotional reasons rather than for nourishment. In addition, after gastric bypass surgery, a patient may be more prone to psychological factors such as depression. Therefore, in order to ensure long-term success, many patients opt to attend support groups both before and after the surgery. Patients may also be asked to see an endocrinologist to rule out glandular or hormonal imbalances.


Patients receive antibiotics before the surgery and often up to 24 hours after the surgery in an effort to minimize the chance for infection. A common complication of any hospital patient that is lying in bed for long periods of time is DVT, or deep vein thrombosis. The inactivity of the legs allows blood clots to form, which can then travel throughout the body and possibly result in a stroke or a pulmonary embolism. In order to prevent this, doctors usually prescribe a pre-operation regimen of compression stockings along with a drug that thins the blood and keeps blood clots from forming. As soon as six hours after surgery, a patient should begin walking around in order to prevent DVT.

Next, we'll look at the exact procedure used in gastric bypass surgery.


Gastric Bypass Surgery and the Stomach

Digestive system

To understand exactly what happens during and after gastric bypass surgery, it's helpful to know a little about the human digestive tract. The stomach is located in the upper abdomen, under the lower ribs. When you swallow food, it moves from your mouth to your esophagus and ultimately lands in the sac-shaped stomach. There, strong stomach acids begin the digestive process. It takes nearly three hours for the food to liquefy and then move into the first section of your small intestine, known as the duodenum. In this section, pancreatic juices and bile speed digestion and the majority of the body's nourishment and calories are absorbed. Food is then moved to the middle section of the small intestine, the jejunum, then on to the final section of the small intestine, the ileum. In these sections, the absorption of calories and nutrients take place on a smaller scale. From the small intestine, any undigested food is passed to the large intestine, where it remains until it is eliminated.

­­Gastric bypass surgery works by altering this digestive process in two ways. It decreases the size of the stomach and causes food to bypass part of the small intestine. These two steps result in the patient feeling fuller more quickly and absorbing fewer calories.


The two gastric bypass surgeries currently in use are the Roux-en-Y gastric bypass and the extensive gastric bypass, or biliopancreatic diversion. The latter of these two surgeries can help a patient lose weight, but it carries of high risk of nutritional deficiencies and a higher risk of death than Roux-en-Y surgery. For this reason, surgeons don't use it as often as they use the Roux-en-Y bypass, which is the most common gastric bypass surgery in the United States.

The Roux-en-Y gastric bypass derives its name from the rearrangement of the small intestines into a Y-shaped configuration. One part of this Y-shape is referred to as a Roux limb. It moves food from the new upper stomach pouch into the small intestine, thus bypassing the lower stomach, the duodenum, and the first portion of the jejunum in order to reduce absorption.


The Procedure

The Roux-en-Y ­gastric bypass procedure
Image courtesy of the National Institute for Diabetes and Digestive and Kidney Diseases

This surgery is performed under general anesthesia and takes approximately four hours. In the first step of the procedure, the surgeon decreases the size of the stomach, which is normally the size of a football, to the size of an egg. To do this, the surgeon staples the stomach together, leaving only a small pouch at the top. He then cuts the small intestine at the jejunum and attaches it to the newly formed stomach pouch. This Roux limb ensures that food will bypass the remaining part of the stomach and the first part of the small intestine.

The section of the small intestine still attached to the lower part of the stomach -- the duodenum -- is then reattached to the middle section of the small intestine, creating a Y-formation just below the stomach. This reattachment allows the stomach to stay healthy enough to continue secretion of digestive juices, which are carried to the midsection of the small intestine to aid in digestion.


These steps make people who have had gastric bypass surgeries feel full sooner, so they don't consume as many calories. They also absorb fewer calories through the small intestine. Patients then burn more calories than they absorb and lose weight as a result.

When surgeons first started performing gastric bypass surgeries, they began by making a large incision in the abdomen. Now, many surgeons perform gastric bypass surgeries through a very small incision. The surgeon inserts a narrow tool called a laparoscope into the incision. The surgeon can guide a tiny camera through this tube to see what is going on inside the abdomen. Doctors and patients often prefer this laparoscopic technique due to its faster recovery rate and decreased risk factors.

During the procedure, patients also have a tube inserted into their nose and passed down to the new, smaller stomach pouch. The tube connects to a suction device that keeps the pouch empty, helping it heal correctly. This surgery is usually completed in about four hours, and most patients stay in the hospital for two to six days to be monitored for any complications.



Gastric bypass patients must learn to eat much smaller portions.
Photo courtesy of Full Tilt Photography

After gastric bypass surgery, patients can remain in the hospital for two to six days. However, recovery in the hospital requires more than just staying in bed. Approximately four to six hours after the surgery, patients usually have to get out of bed for short periods of time to prevent blood clots from forming in the legs. Patients usually have a catheter, which is a small tube attached to the patient's bladder used to collect urine. This tube usually remains in place for 24 hours after the surgery and can be a source of discomfort. The tube used to drain the stomach pouch during surgery may stay in place as well, causing additional discomfort. However, extreme pain should be prevented with proper pain medications.

For the first day or two following the surgery, the patient is not allowed to eat. This gives the stomach a chance to heal. After day two, the patient begins a 12-week diet that starts with the ingestion of liquids, then pureed food and finally small portions of solid foods.


At this point in a patient's recovery, a nutritionist is essential. Because of the loss of the duodenum, absorption of nutrients is decreased and therefore proper of intake of vitamins and minerals should be monitored closely in order to avoid any malabsorption conditions. The new, smaller stomach also means smaller portion sizes for the rest of the patient's life.

Because the postsurgical stomach can initially only hold about an ounce of food, the patient should eat several small meals during the day to prevent vomiting or severe abdominal pain. After three months, the patient should be enjoying three meals and three healthy snacks per day. By this point, the stomach should be slightly bigger, but patients still will not able to consume more than a cup and a half of food per sitting.


A New Life

Serving size isn't the only thing to change in a gastric bypass patient's life. People who have undergone the surgery have to eat and drink slowly to reduce the chance of vomiting. Patients must also chew food thoroughly to make sure it can pass through the new, smaller opening from the stomach to the intestine. In addition, patients must add new foods to their diets one at a time in order to make sure that new stomach will agree with it. Vitamin and mineral supplements become an essential part of the diet and should not be skipped for any reason.

Justin Ness lost more than 100 pounds after gastric bypass surgery in 2004.

Follow-up visits to your doctor can vary, but usually a patient is expected to return to the office within two to three weeks after the surgery. The doctor monitors progress with subsequent visits occurring six weeks, three months, six months and one year after the surgery. During this first year, the doctor assesses a patient's ability to heal, measures for nutritional deficits and monitors the amount of weight loss. After the first year, every gastric bypass patient should check in on an annual basis in order to chart any further weight loss or weight gain. At all of these visits, the doctor checks the patient's blood for anemias and other nutritional deficiencies. Gastric bypass patients are specifically at risk for iron and vitamin B12 deficiencies for the rest of their lives, one reason why the annual checkup is so important.


While we can all agree that weight loss in an obese person is ultimately good for the body, the body can sometimes rebel during the initial phases of rapid weight loss. Within the first three to six months, some people can suffer from body aches, extreme fatigue, dry skin, mood swings and hair loss. After about six months, these symptoms should disappear as the body gets used to the weight loss. Patients should be aware that even with a smaller stomach and fewer absorbed calories, people who don't exercise or who eat unhealthy foods can gain all their presurgery weight back.

Now we'll take a look at a few other weight-loss surgery options.


Other Weight-Loss Surgery Options

Although gastric bypass surgery is the most popular weight-loss surgery in the United States, there are other surgical options as well. One is laparoscopic adjustable gastric banding ("lap banding"), which is the second most popular weight-loss surgery. This laparoscopic surgery also shrinks the stomach to the size of an egg, but it uses an inflatable silicone band wrapped around the upper part of the stomach instead of staples. A surgeon can adjust the band to make it looser or tighter, depending on the patient's needs. This procedure has the advantage of being reversible -- the band can be removed entirely if the patient suffers from any serious side effects.

Another procedure is vertical banded gastroplasty. This procedure also shrinks the stomach to a small pouch by using techniques found in both the Roux-en-Y gastric bypass and lap banding surgeries. The surgeon creates the small stomach pouch using both staples and a plastic band, with no bypass of the small intestines. However, with the introduction of Roux-en-Y gastric bypass and lap banding surgeries, the use of vertical banded gastroplasty has decreased. Only 5 percent of surgeons in the United States perform the procedure. This decline in popularity is partially due to the lack of long-term weight loss in many of the patients.


For some people, the benefits of gastric bypass surgery far outweigh the risks associated with it. Being able to reach a healthy weight can also make the long-term dietary changes required after surgery worthwhile. To learn more about healthy weight loss, weight-loss surgeries and related topics, see the links on the next page.

Lots More Information

Related HowStuffWorks Articles

More Great Links

  • Mayo Clinic: Gastric bypass: Is this weight-loss surgery for you?
  • CDC: Overweight and Obesity
  • WebMD: Gastric Bypass Surgery
  • WebMD: Weight Loss Surgery Fast Facts ­
  • NIDDK: Gastrointestinal Surgery for Severe Obesity