Skip to Main Content

Not just weight loss: the new stomach surgery

Medicine@Yale, 2009 - Mar Apr

Diabetes, apnea cures spark a reassessment of bariatric surgery’s role

Bariatric surgery, long a popular operation for patients who want to lose weight, has gained some weight of its own in recent years. Once called “stomach stapling” and viewed simply as a technique to help the obese shed pounds, the surgery has recently been shown to cure or greatly improve such obesity-related conditions as type 2 diabetes and obstructive sleep apnea—often long before any significant weight is lost.

“There’s been a huge change in the way we think about this surgery,” says Robert Bell, M.D., assistant professor of surgery and director of the Yale Bariatric Surgery Program. “We used to think that if you helped a person lose weight, these weight-related problems would slowly get better as a function of the weight loss.” What actually happens, according to Bell, is that metabolic changes brought on by the surgery cause immediate improvements in the weight-related disorders. Surprisingly, and for reasons that are not fully understood, these metabolic changes apparently don’t occur if the patient loses weight naturally.

These findings prompted the American Society of Bariatric Surgery in June 2007 to change its name to the American Society of Metabolic and Bariatric Surgery, signifying “a shift in emphasis,” Bell says. “It’s not so much about weight loss; it’s really more about getting patients healthier.”

A study published in JAMA: The Journal of the American Medical Association in January 2008 found that 73 percent of patients resolved their type 2 diabetes after gastric banding surgery. Another JAMA study published in October 2004 found that after bariatric surgery, diabetes was eradicated in 76.8 percent of patients and eradicated or improved in 86 percent of patients.

“Unbeknownst to everybody doing this surgery was that there’s a lot more going on than just that the patient filled up more easily,” Bell said. “There’s a variety of hormonal changes that occur that really were not described until this decade. It is these hormonal changes that confer the added medical benefits.”

The first surgical procedure to aid in weight loss was introduced in the 1950s and was purely malabsorptive, meaning that after surgery, a patient could eat anything but only a small percentage would be absorbed. By the 1970s, gastric bypass surgery, a procedure in which the size of the stomach is surgically reduced, thereby restricting the amount of food a patient could eat, began catching on.

Bell said scientists are just beginning to understand the metabolic effects of this procedure. What is known is that favorable changes occur in levels of ghrelin, a hormone produced in the stomach, pancreas and brain that stimulates appetite, and in GLP-1 and GIP, two gastrointestinal hormones that increase the amount of insulin released after eating. How long after surgery it takes for weight-related disorders to improve depends on how long they’ve existed and how severe they are, says Bell. “In somebody who has only had type 2 diabetes for two years, it’s going to be gone before they leave the hospital. If they’ve had type 2 diabetes for 15 years and have been on insulin for seven, it’s going to get better but may not go away.”

The implications of these findings are significant, says Bell, who predicts there will be a move toward earlier interventions, with surgeons operating on patients who are overweight but not yet obese, a transition that will most likely require the compilation of long-term efficacy data to convince insurance companies to change their coverage policies. “Right now you have to be a certain size and have a body mass index (BMI) of 40 or more to be covered,” Bell said. A BMI of between 19 and 24 is considered normal; 25 to 30 is overweight, 30 to 35 is obese and 35 to 40 is morbidly obese. In November, the Centers for Medicare & Medicaid Services, a division of the Department of Health and Human Services, announced that bariatric surgery would not be covered by Medicare of Medicaid for beneficiaries with a BMI below 35.

Bell also anticipates the procedure being performed on younger patients. Bell, who performs about 100 gastric bypass surgeries a year, has done four on 17-year-olds. (Most insurers require the patient to be at least 18.) “It makes sense to help these patients when they’re younger,” he says, “because the years of obesity haven’t added up, causing destruction to bones and joints that limit their exercise, which is key to the long-term success of this surgery.”

Bell knows it will take time for patients, physicians and insurers to view gastric bypass surgery as more than just a weight-loss operation, but in his own practice, that’s exactly what’s happening. “Although we still talk about obesity and weight loss,” Bell says, “we really focus on the fact that it’s a cure for diabetes, hypertension, sleep apnea and high cholesterol.” Medications, the usual course of treatment for these ailments, just manage the symptoms, Bell says. “Surgery eradicates the disease. It’s gone.”

Feeling fuller faster

Bariatric surgery limits the amount of food the stomach can hold by reducing its capacity to a few ounces. Three procedures, all of which are offered by Yale surgeons, are covered by insurance carriers in the United States.

  • In gastric bypass, the stomach is surgically shrunk from the size of a football to that of a golf ball. The smaller stomach pouch is then attached to the middle of the small intestine, bypassing the duodenum, the section of the small intestine that absorbs the most calories.

  • Similar to gastric bypass, bilio-pancreatic diversion with duo-denal switch involves the surgical construction of a sleeve-shaped stomach which is attached to the final section of the small intestine, bypassing the duodenum.

  • In laparoscopic adjustable gastric banding, a silicone band filled with saline is wrapped around the upper part of the stomach to create a small pouch and cause restriction. The size of the restriction can be adjusted after surgery by adding or removing saline from the band.

None of these procedures is a substitute for exercise or healthy eating, cautions bariatric surgeon Robert Bell. “It’s not like you have the surgery and—voila!—you lose all kinds of weight. You have to put a lot of effort into it. It’s an adjunct, a tool to help you lose the weight.”