When Diets Fail: Bariatric Surgery

“A Roux-en-Y gastric bypass is the strangest operation I have ever participated in… (It) removes no disease, repairs no defect or injury. It is an operation that is intended to control a person’s will and to manipulate a person’s innards so that he will not overeat again.” Dr. Atwul Gawande, Complications, 2002.

Human evolution occurred in a world of varying food supply. The body’s ability to store some fat insured survival when food was scarce. For most of us now there are no lean times when a few extra pounds  disappear, so getting rid of them means voluntarily diminishing food intake to amounts less than we require for normal activity. This is easy if we haven’t strayed more than 10-20lb over normal weight. Above this level, gains and losses tend to become cyclical – weight that comes off reappears easily, and tends to increase with each round  of dieting. When obesity becomes “morbid” – in the neighborhood of about 100 excess pounds – weight loss by conventional means is all but impossible.

A surgical way to restrict calories

So far, bariatric (from Greek words bari:heavy weight, iatr: physician, ic: pertaining to) surgery has provided the only long-term solution to morbid obesity, by restricting the amount of food entering the stomach and by altering the route the food takes through the small intestine. Patients who undergo bariatric surgery often see immediate results. Pounds finally melt away and, surprisingly, so do many previous food compulsions. Many patients maintain losses of 60-65% of their excess weight for many years. Most interesting is a profound effect on diabetes that appears before any significant weight disappears. This rapid reversal of impaired glucose control that the surgery triggers has opened a whole new frontier of research. But weight loss surgery is a drastic measure, and no one knows the results of living 30 to 50 years with this type of intestinal re-routing.

Early attempts

Beginning in the 1950s, pioneers in bariatric surgery, doctors and patients alike, learned from early negative experiences. The first approach, stapling the stomach to reduce its size, made patients lose weight, but long term results were poor. Tiny stomach pouches stretched, staple lines broke down and patients were able to eat their way back to obesity. The next approach blocked absorption of food by rerouting its path from the stomach to distant portion of the small intestine, bypassing the upper small intestine where much nutrient absorption normally  occurs. Early procedures bypassed too much small intestine and caused malnutrition, foul smelling diarrhea and a very unpleasant set of symptoms called the dumping syndrome (cramps, nausea, faintness and diarrhea). Refinements of technique resulted in fewer symptoms, though patients require supplementary vitamins and minerals, and some dumping symptoms still occur.

Modern Procedures

Today, gastric “banding” with an adjustable silicone noose placed around the upper stomach and a procedure called vertical gastric banding are the least invasive and most reversible of the commonly done bariatric procedures. They are also the least effective in terms of amount, speed and persistence of weight loss. The best operation for treating obesity is the Roux-en -Y procedure, the type of surgery most commonly meant when the term gastric bypass is used.

Understanding the Roux-en-Y

Under normal circumstances, food travels from the mouth, through the esophagus and into the stomach, which is about the size of two fists. There, it sloshes around for about 20 minutes before passing through a valve to the first part of the small intestine (the duodenum), where it mixes with bile and pancreatic enzymes. After Roux-en-Y surgery, incoming food finds only a tiny pouch of stomach, 5% of its original size, opening directly into the second part of the intestine (the jejunum). Surgical rerouting has separated 95% of the stomach and the the entire length of the duodenum from the food stream and plugged the end of the duodenum back into the system farther down the jejunum. The small amount of food tolerated by the tiny stomach bypasses several feet of small intestine before it meets up with bile and digestive enzymes.

After Surgery

Under the best circumstances, weight loss following Roux en Y surgery is prompt and long-lasting. Initially patients can eat only an ounce or 2 at a time. They must schedule meals and plan content carefully in order to meet their protein and fluid needs and to avoid constipation. Over time they can begin to eat a little more at one sitting. Most patients lose 35-40% of their bodyweight over 12-15 months, and maintain that for at least 15 years. Diabetes is cured in over 80-95% of patients. Hypertension, sleep apnea, acid reflux, arthritis, infertility, stress incontinence, fatty liver, and leg infections also disappear or are significantly improved.

Candidates for Surgery
Given all of these positive results, why not offer this type of surgery to less than morbidly obese patients who struggle to lose weight? Currently weight loss surgery is limited to patients with BMIs (Body Mass Index) of 40, or 35 if the patient already suffers from obesity related diseases like hypertension or diabetes. BMI is a calculation of weight divided by height squared, with measurements expressed in kilograms and meters. A BMI of 30 qualifies a patient as obese; 19-24.9 corresponds to appropriate weight. Statistical analysis of risks and benefits of bariatric surgery set the acceptable range for surgery. Surgical candidates must also undergo extensive medical tests and psychiatric analysis, and have made serious attempts to lose weight. They must understand that gastric bypass is drastic and usually permanent, that complications can be bad, and that success is not guaranteed. Some patients manage to regain all their weight and then some.

Oversight

Bariatric surgery is regulated by American Society of Metabolic and Bariatric Surgery, which sets professional standards for hospitals and surgeons, establishes centers of excellence, and promotes research and data collection about the procedures. In 2007, surgeons performed over 200,000 surgeries for obesity, up from around 16,000 in 1992. Advances in laparoscopic surgery have made recovery faster and less uncomfortable. The best surgical mortality rates are 1% and peri-operative complication rates 10% – acceptable numbers given the worse risks of morbid obesity.

Complications and Long Term Results

Possible complications of bariatric surgery  include blood clots travelling to the lungs, heart attack, respiratory compromise, suture line leaks, hernias, ulcers, GI bleeding, bowel obstruction, and gallstones. Calcium iron and some vitamins are not well absorbed and they require life-long monitoring and supplementation. All bariatric surgeons emphasize that long term success depends on patient cooperation with major eating and lifestyle changes forever. This is especially important when the choice of procedure involves only change in stomach size, as is the case with the gastric banding procedures.

Clues about metabolism and diabetes

Sheer calorie restriction accounts for some of the success of all types of bariatric surgery. When the surgery also bypasses a segment of small intestine, more is at work than meets the eye. The rapid disappearance of diabetes before significant weight loss occurs and the remarkable loss of previous cravings are clues to unappreciated biochemical and hormonal complexity of the intestines. The surgical assault on obesity appears to have much to teach us about energy metabolism and diabetes. One day, hopefully, such strange surgery will be unnecessary.

Resources:
American Society of Metabolic and Bariatric Surgery (http://www.asmbs.org/): Access to readable, professional information regarding bariatric surgery.
http://www.obesityhelp.com/: Support group website for patients contemplating surgery or looking for related information

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