Obesity (Bariatric Surgery)

Medical Author:
Medical Editor:

Obesity and Health Facts

Obesity is a chronic (long-term) disease that is increasing in frequency. More than half of American adults are overweight. Nearly one third are obese.

Obesity is the second leading cause of preventable deaths in the United States (tobacco is the first). People who are obese have much higher risks of many serious health problems than nonobese people. Obesity affects every system of the body. Obesity increases the risk of illness from about 30 serious medical conditions.

The most devastating of these health problems include the following:

Measuring Obesity

A measure called the body mass index (BMI) is used to assess your weight relative to your height.

What does the BMI mean?

  • Healthy BMI = 18.5-24.9
  • Overweight = 25.0-29.9
  • Obese = 30 or greater
  • Morbidly obese = 40 or greater

To calculate your body mass index on the internet, fill in your height and weight at the Web site of the United States government's National Heart, Lung, and Blood Institute's Obesity Education Initiative.

Nonsurgical Treatment of Obesity

The first step toward weight loss is to eat less and to exercise more. The goal is not to lose all the excess weight. Losing even 10% of your weight can significantly lower you risk of developing obesity-related medical problems. However, over the long term, these strategies alone are not always successful for weight loss. A small percentage of individuals who participate in weight loss programs lose significant amounts of weight and maintain that loss for a long period.

Surgical Treatment of Obesity (Bariatric Surgery)

Surgical treatment of obesity is also known as bariatric surgery or weight loss surgery. Surgery is currently the most effective treatment for morbid obesity resulting in durable and sustainable weight loss and accompanying health improvements.

Digestion: The Basics

Before you can learn about operations used to treat obesity, you need to know a little bit about the process of digestion.

  • The process of breaking food down into the substances used by the body is called digestion.
  • Digestion begins in the mouth, where chewing breaks food up into small particles.
  • After swallowing, the food moves through the esophagus, stomach, and intestines (bowels), also called the "digestive tract."
  • As food moves through the digestive tract, it is broken down by enzymes and digestive juices.
  • Once broken down in this way, individual components of the food such as proteins, carbohydrates, and other nutrients are absorbed into the wall of the small intestine. Different components of food are absorbed in different parts of the small intestine known as the duodenum, jejunum, and ileum.
  • The process is aided by strong acids in the stomach and by bile and pancreatic enzymes in the duodenum.
  • Undigested food particles collect in the large intestine (colon). They are eliminated from the body as feces.

Criteria for Bariatric Surgery

Weight loss surgery candidates must fulfill all the following criteria:

  • Body mass index (BMI) greater than 40 or a BMI of at least 35 with obesity-related medical problems such as diabetes, heart disease, hypertension, sleep apnea, or high blood lipids
  • Previously attempted nonsurgical weight-loss treatments and failed to achieve long-term weight loss
  • Well-informed and motivated for long-term follow-up to achieve substantial weight loss
  • Acceptable medical risks for surgery

Classifications for Bariatric Surgery

Surgeries for weight loss can be classified as follows:

  • Restrictive procedures that limit the amount of food intake by reducing the size of the stomach
  • Malabsorptive procedures that interfere with absorption of food from the digestive tract
  • Combined restrictive and malabsorptive procedures

The 2 most commonly performed operations for weight loss in the United States are the Roux-en-Y gastric bypass (RYGB) and the adjustable gastric band (AGB). Both procedures could be done laparoscopically with smaller incisions than those required for traditional open approach (laparotomy). Small incisions result in less pain, early ambulation, and rapid postoperative recovery and less chance for wound complications (wound infection, fluid collection, and hernia).

Preoperative Workup for Bariatric Surgery

Careful preoperative patient screening, selection, preparation, and education are the keys for postoperative success. A comprehensive multidisciplinary approach to patients' screening and education, including consultations with a dietitian, psychologist, internist, and bariatric surgeon is mandatory. In selected cases, cardiac, pulmonary, and endocrine evaluation may be needed. Patients should have a clear understanding and realistic expectation of benefits, risks, and long-term consequences of surgical treatment.

Operative Procedures for Bariatric Surgery

Gastric bypassRoux-en-Y gastric bypass is the most commonly performed weight loss procedure in the United States. This operation both restricts food intake and limits absorption of food. A part of the stomach is closed off, creating a small pouch. This restricts the amount of food that you can eat at one time. The small pouch of the stomach is connected directly to the small bowel. As the name implies, food bypasses the stomach and the first portion of the small intestine. Because a part of the small bowel is bypassed, less food is absorbed. Most people find they can eat less than 1 cup of food at a time after the operation. Food must be chewed very well. Overeating or not chewing food finely will result in cramping, nausea, and vomiting.

Laparoscopic adjustable gastric bindingThis is a purely restrictive procedure. It involves placing an inflatable silastic band around the uppermost part of the stomach. This results in a smaller upper stomach pouch and a narrow opening between the upper and lower parts of the stomach. This induces and early feeling of fullness and thereby decreases food intake. It is adjustable by changing the volume of saline in a surgically placed subcutaneous reservoir, thereby tightening or loosening the band.

Biliopancreatic diversion Biliopancreatic diversion (BPD) is a malabsorptive procedure with some restrictive component. A part of the stomach is removed and the remaining part is attached directly to the small intestine near its end. BPD is used much less often than Roux-en-Y because it has a greater risk of complications.

Vertical banded gastroplastyVertical banded gastroplasty (VBG, stomach stapling) is a restrictive procedure that traditionally was done by applying bands or staples to the stomach. This procedure is rarely performed today due to the high failure rate. More information about these procedures can be obtained by visiting the American Society for Bariatric Surgery or the Bariatric Multidisciplinary Institute.

Benefits and Risks of Weight-Loss Surgery

Like all surgical procedures, weight-loss operations have benefits and risks. No one should decide to have surgery without being completely informed of both the pros and cons. This is a decision that you make with your family members, your health care provider, and your surgeon.

Benefits of weight-loss surgery

  • Weight loss: Most patients begin to lose weight right away. Some gain some of the weight back, but most are able to keep the weight off for long periods.
    • In general, combined restrictive and malabsorptive procedures (like gastric bypass) are more successful than restrictive procedures (like adjustable gastric banding) at promoting weight loss.
      • Gastric bypass is the most successful procedure. In the first 2 years after gastric bypass, average weight loss is 65% of excess weight. On the other hand, average weight loss with AGB is 35% of excess weight.
      • With gastric bypass, no band is introduced into the body. Also, it is a good operation for a sweet eater because eating sugar makes the patient feel ill (referred to as "dumping").
      • The lap-band system has the advantages of being less invasive, providing a faster recovery, and avoiding alteration of anatomy of the gastrointestinal tract. It is adjustable and reversible with normal stomach restoration. No opening of the stomach or intestines occurs that could cause a leak.
    • People who undergo one of these procedures are much more likely to reach their goal and keep weight off if they also adopt a plan of healthy eating and regular exercise.
  • Improved health: Most obesity-related medical conditions improve drastically after surgery, especially diabetes, sleep apnea, and hypertension.
    • After surgery mortality rate is reduced and improvements are seen in many of the health risks associated with obesity.
    • Overall, quality of life, self image, and mobility are reported to be better.

Risks of weight-loss surgery

All surgical procedures have complications. Talk to your surgeons about this and make sure that your surgeons are specialists in bariatric surgery.

  • Disadvantages of gastric bypass - A patient who has gastric bypass may develop the following complications:
    • "Dumping syndrome" - Patients experience nausea, abdominal cramping, and diarrhea after eating sugar. Other symptoms include weakness or faintness.
    • Narrowing or ulcer formation or leak at the stomach to intestine connection - These may require reoperation.
    • Incisional hernia - This is more common in open bariatric surgery.
    • Blood clot in the leg - This may migrate to the lung.
    • In addition to surgical complications, long-term consequences of the malabsorption arise if patients with gastric bypass do not take supplemental vitamins, iron, and calcium. These nutritional deficiencies include the following:
      • Vitamin deficiencies (A, B-12, D, E, and K) - Deficiencies of vitamin B-12, folate, and iron can cause anemia.
      • Mineral deficiencies (calcium, iron, and folic acid) - Calcium deficiency is a concern because it may lead to osteoporosis and other bone disorders.
  • Disadvantages of adjustable gastric band
    • The lap-band system is not the operation of choice in sweet eaters or patients with severe gastroesophageal reflux disease (GERD).
    • There is a low possibility of port leak or infection, as well as slippage, erosion, or migration of the band. This may require re-operation. High conversion rates of band to gastric bypass have been reported in American studies and may reflect patient selection.

In experienced hands, the benefits of surgery are typically viewed to outweigh the risks. The immediate operative mortality rate for both adjustable gastric band and Roux-en-Y gastric bypass is about 1%.

Weight regain after bariatric surgery

Some patients may regain weight after bariatric surgery. This may be due to many factors, among them the following:

  • Noncompliance with postoperative diet
  • Noncompliance with postoperative exercise
  • Stretching of the stomach pouch
  • Communication between the pouch and the rest of the stomach
  • Band problems

Costs of weight loss surgery

Surgery seems to be much more expensive than other treatments for obesity, but is cheaper than the treatment of all the complications of obesity. However, rates vary depending on choice of surgeon and hospital and region in which you live. Check with your carrier to see whether such operations are covered. Surgery may be covered by Medicare or Medicaid; check with your regional office.

Postoperative Care for Bariatric Surgery

If you undergo weight loss surgery, you will continue to receive close medical care for the rest of your life. Laparoscopic adjustable gastric banding will require more frequent visits for band adjustment. Postoperative dietary (including vitamin, mineral, and possibly liquid protein supplementation), exercise, and lifestyle changes should be reinforced by counseling, support groups, and working with your primary care physician. Postoperative care may include planning for reconstructive operations after weight stabilization for certain patients.

Reviewed on 11/20/2017

Medically reviewed by John A. Daller, MD; American Board of Surgery with subspecialty certification in surgical critical care


"Surgical management of severe obesity in adolescents"

Patient Comments & Reviews

The eMedicineHealth doctors ask about Obesity (Bariatric Surgery):

Surgery in the Treatment of Obesity - Patient Experience

Tell us about your obesity surgery (bariatric surgery).

Health Solutions From Our Sponsors