Obesity is the most prevalent metabolic disorder today in the U.S. Men who are more than 125 percent of their ideal body weight (IBW) or women who are more than 130 percent of their IBW are considered obese, while the term clinically severe obesity refers to individuals more than 200 percent of their IBW or 100 pounds above IBW. Forty percent of adult Americans are obese, as are 20 percent of American children aged 6 to 18. Three to five percent of American adults are more than 100 pounds above their IBW. It is estimated that at any one time, 15 to 35 percent of American adults are dieting in an attempt to lose weight. Ideal body weight (see figure 1) is calculated from using tables first developed in 1959 by the Metropolitan Life Insurance Company.
Doctors have developed the term Body Mass Index (BMI) to account for an individual’s height when describing their weight. BMI is calculated using the formula (weight in kilograms/height in meters2). Normal BMI is between 20 and 25 kg/m2. An individual is considered mildly obese with a BMI of 27 to 30, moderately obese with a BMI of 30 to 35, and severely obese with a BMI in excess of 40. For an adult male of average height, a BMI of 40 corresponds to approximately 100 pounds above IBW.
Theories blame everything from genetics to sedentary lifestyles and the glut of fast food for rising weight. But regardless of the cause, experts on obesity have been forced to acknowledge that for the majority of obese patients, diet, exercise, and weight-loss drugs simply do not work, with long-term failure rates above 90 percent.
Obesity is associated with many medical problems. They include increased risk of heart disease, high cholesterol, high blood pressure, diabetes, heartburn, gallbladder disease, sleep problems, and degenerative joint disease. For women, cancers associated with obesity include: uterine, gallbladder, cervix, ovary, and breast. For men, cancers associated with obesity are colon, rectum, and prostate cancer. Many severely obese people are depressed, experience difficulty with daily activities, and rely on others for care, transportation, and hygiene. It is thought that 300,000 people every year die in the U.S. due to the medical consequences of severe obesity.
The economic cost of obesity is staggering—$30 billion each year is spent on treating the medical complications of obesity, with Americans spending another $30 to 50 billion on diets and other over-the-counter weight-reduction treatments.
Surgery for obesity should be considered a treatment of last resort after dieting, exercise, psychotherapy, and drug treatments have all failed. The 1991 National Institutes of Health Consensus Conference on Gastrointestinal Surgery for Severe Obesity concluded that “patients whose BMIs exceed 40kg/m2 are potential candidates for surgery if they desire substantial weight loss because obesity severely impairs the quality of their lives...” In certain instances, less severely obese patients (those with a BMI of between 35 and 40kg/m2 ) may also be considered for surgery. Included in this category are patients with high-risk comorbid conditions such as life-threatening cardiopulmonary problems or severe diabetes mellitus.
There are a number of operations that have been used in the treatment of clinically severe obesity. They are known collectively as bariatric surgery, a term coined from the Greek words for weight and treatment. The surgery, which is becoming increasingly popular, mirrors the rise in obesity and the failure of diet, exercise, and weight-loss drugs. Approximately 40,000 weight-reduction procedures are currently performed in this country every year, up by 50 percent just five years ago. Eighty percent of the patients are women; most are middle-aged or younger.
The intestinal bypass was the first operation performed for weight loss over 40 years ago (see figure 2). It worked by severely limiting the length of intestine available to absorb calories from food. Although patients rapidly lost weight, they also lost essential nutrients (e.g., vitamins and protein) and often died of liver failure and malnutrition. The biliopancreatic diversion and a related procedure, the duodenal switch, are recent modifications of the intestinal bypass that also cause weight loss by malabsorption (see figure 3). They allow patients to eat normal size meals, but still put patients at long-term risk for nutritional complications. These operations are commonly performed in Europe, where they were first developed, but have recently been gaining popularity in the U.S.
Vertical banded gastroplasty (VBG)
The vertical banded gastroplasty (VBG) restricts the amount of food that can easily pass through the stomach at any one time (see figure 4). It uses a plastic band and four to six rows of steel staples around the stomach near the gastroesophageal junction, creating a small pouch and a narrow passage into the larger remainder of the stomach. Popular in the past, the VBG now only accounts for around 15 percent of all weight reduction operations performed in the U.S. each year. Common problems seen with the VBG include an inability to tolerate solid food, leading to sometimes daily vomiting. This is due to obstruction at the level of the plastic band. Patients often resort to eating high calorie liquids or soft foods, which can pass easily through the band (e.g., ice cream and milkshakes), and many regain whatever initial weight loss they experience after the surgery.
Laparoscopic surgery is “key-hole surgery” using instruments placed into the abdomen through five or six small incisions. This band consists of an outer plastic ring and an inflatable “inner-tube” that contains saline. The inner-tube is attached to a reservoir and placed under the skin of the abdominal wall. The band is placed laparoscopically around the top of the stomach just below the esophagus. The saline can be injected into or removed from the reservoir to vary the degree of restriction to the passage of food into the stomach. The “lap-band” therefore works like a variable version of the VBG.
The current gold standard for the surgical treatment of clinically severe obesity is the gastric bypass (GB) (see figure 6). This operation was first performed for obesity over 30 years ago and was developed after surgeons observed massive weight loss in patients undergoing gastric surgery for ulcers or cancer. Approximately 75 percent of all operations performed for severe obesity in the U.S. are now of this type. A small pouch (around 30 cc or one fluid ounce in size) is created by stapling across the top of the stomach, causing massive restriction in food intake. A section of the small intestine (two to five feet in length) is attached to it so that food can bypass the duodenum and the first portion of the small intestine, reducing calorie and fat absorption. The opening from the pouch to the small bowel is kept small (around one-half inch) so that food and fluids can only pass very slowly into the intestine, again limiting the number of calories that can be absorbed from food at any one time. GB surgery has been shown to induce greater weight loss than the VBG in several large trials.
Gastric bypass surgery can now be done laparoscopically. Laparoscopic GB surgery is technically difficult surgery and surgeons require special skills and training to perform it safely. Its relative benefits over the “open” or conventional approach include a lower rate of wound infection, less postoperative pain, smaller scars, and a slightly shorter period of hospitalization and recuperation after surgery. It does, however, carry a higher risk of leaks from the staples holding the pouch and small intestine together, particularly if the surgeon has only performed a limited number of the procedures. The risks of laparoscopic GB are greater in patients with higher BMI, although some surgeons have reported safe performance of the procedure in patients with BMIs in excess of 60.
On average, most patients can expect to lose 75 percent of their excess weight 12 to 18 months after GB surgery. At East Carolina University School of Medicine, in Greenville, NC, a research team led by Dr. Walter Pories has kept records on 608 patients and found that almost 90 percent of initial weight loss can be maintained for more than a 14-year period.
Physically and emotionally, the benefits are profound. Diabetes, high cholesterol, and high blood pressure can be cured in more than 90 percent of patients undergoing successful gastric bypass surgery. Many breathing problems, including asthma and sleep apnea (a life-threatening disorder that forces many obese patients to sleep with oxygen masks) completely disappear after surgery too. Chronic and painful leg ulcers heal, and patients enjoy relief from disabling back and leg pains.
Patients no longer face the social stigma or the many indignities attached to obesity (see figures 7 and 8). They can begin to enjoy going to ballgames as now they can squeeze through turnstiles. They can travel long distances to visit family and friends without having to pay for two airplane seats. They now find attractive clothes that fit. Many patients who were on disability can go back to work. Women who had been infertile because of hormonal problems linked to obesity find that after successful surgery, they can have children.
The surgery is not, however, a quick fix or an easy way out. It is a drastic step, carrying all the pain and risk of any major abdominal operation. One percent of patients die after gastric bypass surgery, usually due to surgical, cardiovascular, or pulmonary complications. Common complications include leaks from the staples or stitches holding together the stomach pouch and small intestine (three percent of cases), blood clots in the legs or lungs (three percent), wound infections (15 to 20 percent) and incisional hernias (10 to 20 percent). Narrowing of the connection between the pouch and small intestine due to scar formation occurs in 15 percent of patients (leading to nausea and vomiting), but it can normally be treated with endoscopy (an outpatient procedure wherein a camera on a flexible tube is placed down the patient’s throat and esophagus and into the stomach). An estimated 10 to 20 percent of patients need follow-up surgery for complications such as obstruction due to adhesions (bands of scar tissue in the abdominal cavity).
Gastric bypass surgery can be reversed if necessary (e.g., due to excessive weight loss or life-threatening nutritional deficiencies), but this is only needed in less than one percent of all patients undergoing the procedure. Plastic surgery, to remove excess skin from the abdomen, arms, and legs may be necessary, although this typically is only done 12 months or so after gastric bypass, when the patient’s weight has begun to stabilize.
Bariatric surgery forces people to change their eating habits radically and makes them violently ill if they overeat. Patients put themselves at lifelong risk for major nutritional deficiencies if they do not take daily nutritional supplements. Gastric bypass seems to work in large part by enforcing a strict low-calorie diet. At first, patients lose their appetites and cannot eat more than a few bites at a time without feeling full.
For the first few months, most can only take in 400 to 600 calories a day. If they eat sweets or consume high-calorie drinks (e.g., regular sodas), most will suffer dumping syndrome, which occurs when too much food containing sugar or fat passes too quickly into the small intestine. Dumping causes nausea, weakness, sweating, faintness, and sometimes diarrhea, and most patients say it is so awful that they will do anything to avoid it.
After a year or so, as the pouch stretches, most patients can consume 1,200 calories a day, but we urge them not to exceed that amount. Initial weight loss can only be maintained if patients do not exceed this daily calorie limit. It also becomes possible to cheat. People who nibble cookies or potato chips all day, or sip milkshakes, can "out-eat the pouch" and get fat again, particularly if they become immune to the effects of the dumping syndrome. For that reason, surgeons insist that the operation is merely a tool to help patients lose weight and that it will not work if they misuse it. Successful patients are active participants in the postoperative process and use the operation to make new and healthy lifestyle choices. Maximum weight loss requires the introduction of a healthy diet and a regular regimen of exercise into the lives of patients undergoing gastric bypass surgery. We stress to our patients the need to walk two miles a day at least three times a week to ensure optimal results after the procedure.