Patient information: Weight loss surgery

WEIGHT LOSS OVERVIEW

Obesity is a major international problem and Americans are among the heaviest people in the world. A person is categorized as underweight, healthy weight, overweight, or obese based on his or her body mass index (BMI). Body mass index is a standardized measure of body fat that can be calculated based on an adult's height and weight; a BMI of 25 to 29.9 is considered overweight, while a BMI of ≥30 is considered obese (calculator 1).

Bariatric surgery (from the Greek words "baros" meaning "weight", and "iatrikos" meaning "medicine") is the collective term for a group of surgical procedures that may be used to promote weight loss in certain cases.

SHOULD I HAVE SURGERY TO LOSE WEIGHT?

Surgical procedures are recommended ONLY for people with severe obesity who have not responded to diet, exercise, or medication; for those with less severe obesity, the risks of the surgical procedure may outweigh any potential benefits. Candidates should be sure they understand the implications of bariatric surgery and are willing to commit to the lifestyle changes necessary for reaching and maintaining a healthy weight following the procedure.

The National Institutes of Health recommend that surgery be considered for people at the following weight levels:

• Patients with a body mass index >40 kg/m2
• Patients with a body mass index between 35 and 40 kg/m2 who also have serious medical problems (including diabetes, disabling joint conditions such as arthritis, or obstructive sleep apnea) that would improve with weight loss.

This discussion will focus on surgical management of obesity. Nonsurgical treatment options are reviewed separately. (See "Patient information: Weight loss treatments".)

PREPARING FOR WEIGHT LOSS SURGERY

Most patients in the United States who undergo a weight loss surgery must meet with several healthcare providers before surgery is scheduled. This often includes a nutritionist and mental health specialist. Some patients need to work with these providers for several weeks or months before proceeding with surgery.

• The nutritionist ensures that the patient understands and can follow the strict dietary guidelines necessary after surgery. Some patients will be required to lose a small amount of weight before surgery.
• The mental health specialist helps the patient to identify factors involved in stress, coping, and lifestyle.

Other healthcare providers may also be involved in the presurgical evaluation, including a cardiologist, internal medicine specialist, or sleep medicine specialist. A cardiologist helps to ensure that the patient's heart is healthy enough for surgery. An internal medicine provider may be needed to assess the patient's overall health. A sleep medicine specialist can determine if the patient has a common obesity-related condition, sleep apnea. Sleep apnea can cause difficulty breathing while sleeping and may pose a risk around the time of surgery.

TYPES OF WEIGHT LOSS SURGERY

Weight-loss surgery can be divided into the following categories: restrictive, malabsorptive, and mixed or combination. A comparison of these procedures is available in table 2 (table 1). All of these procedures are performed under general anesthesia (the patient is given medication to induce sleep).

Restrictive — Restrictive procedures reduce the size of the stomach, limiting the amount of food that can be consumed at once. There are several types of restrictive surgeries.

Lap banding — Laparoscopic gastric banding (LAGB), or lap banding, is a restrictive procedure that uses a silicone band around the entrance to the stomach (figure 1). This procedure is done laparoscopically, which means that the surgeon makes small incisions and inserts an instrument with a tiny camera to perform surgery without cutting open the abdomen. The band is connected to a narrow tube that extends to an access port just beneath the skin; a healthcare provider can narrow or widen the entrance to the stomach by injecting or removing saline through the port. The surgery causes the patient to feel full after eating small amounts of food.

Lap banding is a popular choice of weight-loss surgery because it is relatively simple to perform, can be adjusted or removed, and has a low complication rate.

The procedure's effectiveness is variable; excess weight loss ranges from 45 to 75 percent after two years. Using the above example, a person who is 120 pounds overweight could expect to lose approximately 54 to 90 pounds in the two years following lap banding.

Sleeve gastrectomy — Sleeve gastrectomy is sometimes performed on patients with a BMI of greater than 50. This procedure involves the removal of the majority of the stomach to create a smaller, tubular (sleeve-shaped) stomach that can hold less food and is resistant to stretching.

Although sometimes done without plans for more surgery, sleeve gastrectomy is most often performed with the intention of doing another procedure, such as a gastric bypass or biliopancreatic diversion at a later date. It is often difficult to operate on extremely obese patients, and performing a sleeve gastrectomy allows the patient to lose some excess weight before undergoing a second, more intensive procedure (see 'Gastric bypass' below and 'Biliopancreatic diversion' below.

Expected excess weight loss is approximately 33 percent after two years. Using the above example, a person who is 120 pounds overweight could expect to lose 40 pounds in the two years following surgery.

Malabsorptive — The goal of malabsorptive surgical procedures is to decrease the length of small intestine through which food must pass, thereby reducing the absorption of nutrients and calories and inducing weight loss. Biliopancreatic diversion, with or without duodenal switch, is the most common malabsorptive procedure.

Biliopancreatic diversion — In biliopancreatic diversion (BPD), part of the stomach is removed, and the remaining section is surgically connected to the lower part of the small intestine. Weight loss occurs primarily because food passes into the large intestine before most of the nutrients and calories can be absorbed in the small intestine.

Mixed — Mixed or combination procedures have both a restrictive and malabsorptive component, meaning that they limit food intake while also decreasing absorption of nutrients within the body. Gastric bypass is the most common mixed surgical procedure used to treat weight loss in the United States.

Gastric bypass — Roux-en-Y gastric bypass (RYGB) is primarily a restrictive procedure, but also has a malabsorptive element, making it more successful than a solely restrictive surgery.

The surgeon creates a small stomach pouch by dividing the stomach, and attaches it to the small intestine (figure 2). The pouch is only able to hold about an ounce of food (the approximate equivalent of one slice of bread or 1/2 cup of cooked rice or pasta), causing a feeling of fullness after consuming a very small amount; over time, the pouch stretches to hold about one cup. Additionally, the body absorbs fewer calories since food bypasses the majority of the stomach as well as the upper small intestine (duodenum). This kind of new intestinal arrangement (Roux-en-Y) seem to cause decreased appetite and improved metabolism by changing the release of various hormones.

RYGB can be performed as open surgery (through a large incision in the abdomen) or laparoscopically. The laparoscopic procedure, if technically possible, is preferred because patients typically require less time to recover and have fewer complications.

RYGB has a high success rate, and patients lose an average of 62 to 68 percent of their excess body weight in the first year. Weight loss typically plateaus after one to two years, with an overall excess weight loss between 50 and 75 percent. For a person who is 120 pounds overweight, an average of 60 to 90 pounds of weight loss would be expected.

WEIGHT LOSS SURGERY COMPLICATIONS

A variety of complications can occur with surgical weight loss procedures. The specific risks depend upon the procedure used and any preexisting medical conditions. In addition, complications are less likely when surgery is performed in centers with vast experience in bariatric surgery. Common potential complications of bariatric surgery include pulmonary embolus, bleeding, infection, narrowing of outlets, and hernias at the incisions.

EFFECTIVENESS OF WEIGHT LOSS SURGERY

The goal of any weight-loss surgery is to reduce the risk of illness or death associated with obesity, and to improve body system and organ function. Research has shown that bariatric surgery is effective in achieving these objectives, and also has additional benefits such as reducing the amount of money spent on medication, cutting down on sick days, and improving quality of life.

One study of bariatric surgery outcomes showed that overall, patients lost an average of 61 percent of their excess weight; total weight loss varied depending on the specific procedure performed [1]. Other conditions caused or worsened by obesity also improved to the point of needing less or no treatment; these included diabetes (86 percent of patients), hyperlipidemia or high blood cholesterol (70 percent), high blood pressure (79 percent), and obstructive sleep apnea (84 percent).

In addition to achieving weight loss, patients who undergo bariatric surgery are significantly less likely to develop heart disease, cancer, and endocrine, infectious and psychiatric disorders, although they are more likely to develop digestive diseases.

AFTER WEIGHT LOSS SURGERY

In the hospital — Post-operative pain is controlled with medication. Many bariatric surgery patients are given "patient-controlled analgesia" while still in the hospital; this delivers pain medication through an intravenous line (IV) in the hand or arm. Patients are able to control, within preset limits, when a dose is given.

Patients will typically remain in the hospital for a day or two after surgery, during which time pain, mobility, and food intake will be monitored. Following surgery, patients will work with a healthcare provider and dietitian to establish guidelines for eating and activity after discharge from the hospital.

At home — A strict diet of liquids and soft foods (such as yogurt, scrambled eggs, and cottage cheese) must be followed for about six weeks following surgery; a dietitian can recommend soft or pureed foods that will provide adequate nutrition. It is important to follow eating guidelines during the weeks, months, and years following surgery in order to maintain a healthy weight and ensure that an adequate number and type of nutrients are eaten.

Instructions generally include slowly increasing calorie intake over time, eating small meals, chewing slowly and thoroughly, separating food and fluid intake by at least 30 minutes, and avoiding foods high in fat or sugar. Vitamin supplements may also be prescribed.

Most patients will be encouraged to get out of bed and start walking the day after surgery to prevent blood clots from forming in the body; however, strenuous activity is not recommended until the incisions have healed. Driving should be avoided if the patient is taking any pain medication stronger than acetaminophen (Tylenol). Patients are encouraged to begin a regular fitness program as soon as possible after healing; a healthcare provider can help recommend appropriate and beneficial forms of exercise.

Results of surgery — It usually takes between one and two years for maximum weight loss to occur. After reaching a plateau at a healthy weight, some patients have plastic surgery (called "body contouring") to remove excess skin from the body, particularly in the abdominal area.

Although bariatric surgery can produce dramatic results, it is crucial that the patient make a commitment to maintaining a healthy lifestyle, including follow-up contact with a healthcare provider to monitor progress. It can be difficult to make lifestyle adjustments after weight-loss surgery, and patients should be aware that they will have to work to develop and stick to new habits.

Recovery and the subsequent weight management can be stressful and emotional, and it is important to have the support of family and friends. Professional counseling with a social worker or therapist should be considered if patients experience anxiety or depression.

SUMMARY

• Weight loss surgery is only recommended for severely obese people. Surgery may be recommended for moderately obese people who have another illness such as diabetes, severe arthritis (or other joint problems), or sleep apnea (see 'Should I have surgery to lose weight?' above.
• There are three types of weight-loss surgery. The best type of surgery depends upon how much weight needs to be lost. The most common surgeries are lap banding and gastric bypass (see 'Types of weight loss surgery' above.
• One surgery, called lap banding, can be adjusted or removed. This procedure places a band around the top of the stomach (figure 2). This causes the person to feel full after eating a small amount of food (see 'Lap banding' above.
• In gastric bypass, the doctor creates a small pouch in the stomach. The pouch is connected to the small intestine. These changes cause the person to feel full after eating a small amount of food. It also causes the body to absorb fewer calories from food. (See 'Gastric bypass' above.)

• Weight loss surgery can have complications, such as pain, infection, need for a second surgery, or nutrition problems). The specific complication depends upon which surgery is done and if the person has other medical problems. There is a smaller risk of complications when weight loss surgery is done in centers with a great deal of experience. Less than 1 in 100 people die because of weight loss surgery. (See 'Weight loss surgery complications' above.)

• After surgery, people lose about 60 percent of their extra weight (just over 73 pounds for a person who needs to lose 120 pounds); the amount of weight lost depends upon which surgery is done. Other health problems (eg, diabetes or arthritis) often improve after weight loss surgery. (See 'Effectiveness of weight loss surgery' above.)

• After surgery, it is important to eat the right foods and exercise to stay healthy. Help with diet and exercise planning is available (see 'After weight loss surgery' above.

WHERE TO GET MORE INFORMATION

Your healthcare provider is the best source of information for questions and concerns related to your medical problem. Because no two people are exactly alike and recommendations can vary from one person to another, it is important to seek guidance from a provider who is familiar with your individual situation.

This discussion will be updated as needed every four months on our web site (www.uptodate.com/patients). Additional topics as well as selected discussions written for healthcare professionals are also available for those who would like more detailed information.

Some of the most pertinent include:

Patient Level Information:
Patient information: Weight loss treatments

Professional Level Information:
Approach to the patient with weight loss
Behavioral strategies in the treatment of obesity
Dietary therapy for obesity
Drug therapy of obesity
Overview of therapy for obesity in adults
Role of physical activity and exercise in obesity
Surgical management of severe obesity

A number of web sites have information about medical problems and treatments, although it can be difficult to know which sites are reputable. Information provided by the National Institutes of Health, national medical societies and some other well-established organizations are often reliable sources of information, although the frequency with which they are updated is variable.

• National Library of Medicine

      (www.nlm.nih.gov/medlineplus/healthtopics.html)

• The Hormone Foundation

      (www.hormone.org)

• The American Gastroenterological Society

      (www.gastro.org)

• The American College of Gastroenterology

      (www.acg.gi.org)

• American Obesity Association

      (www.obesity.org)

UpToDate wishes to acknowledge Kelly Crowley for her contributions to this topic.

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