More patients eligible for bariatric surgery, but number of procedures remains small

Advances in surgical techniques and increased knowledge about the effectiveness of the procedure have led to rising rates of bariatric surgery procedures in the United States between 2011 and 2015. Despite this increase, only a very small percentage of eligible patients undergo this potentially lifesaving surgery.

John Magaña Morton, MD, MPH, chief of bariatric and minimally invasive surgery at Stanford University Medical Center, told Endocrine Today. “I think part of the reason is that there’s still a lack of education around bariatric surgery.”

Even more of a rarity are bariatric surgery cases that result from a physician referral. According to Lee M. Kaplan, MD, PhD, director of the Obesity, Metabolism and Nutrition Institute at Massachusetts General Hospital, only 10% to 20% of bariatric surgery procedures result from referrals.

“There are approximately 200,000 operations a year, so that’s only about 20,000 that result from referral by another provider,” Kaplan said. “When you consider the prevalence of the disease, bariatric surgery is not very common.”

Understanding the disease

Underlying many of the misconceptions about bariatric surgery are misconceptions about obesity itself, Kaplan said.

“I think most people don’t understand obesity; many people don’t consider it a disease,” he said. “They think it’s a lifestyle choice, that body weight is totally under the voluntary control of the individual. If you start with that perception, then something as aggressive as surgery would seem inappropriate. In fact, many physicians and other providers think that drugs are inappropriate, for the same reason.”

Morton explained that people with obesity have an extremely difficult time losing weight, and even if they achieve short-term weight loss, they almost always regain that weight after they have stopped dieting.

“I think with better understanding of the disease, you realize that once a patient gets a BMI over 30 kg/m², it’s very difficult to lose weight on your own. The success rate is about 5%,” he said. “I think this was best exemplified in the Biggest Loser Study, which showed that every single one of these patients not only regained their original weight, but gained some more in addition.”

After a patient has lost weight acutely and is no longer dieting, hormonal adaptations in the body prompt increases in hunger hormones, such as ghrelin, a hormone produced in the fundus of the stomach. 
“There is permanent adaptation when people diet, where ghrelin actually goes up afterward,” Morton said. “People are not only contending with decreased energy expenditure, which happens when you lose weight, but they also have increased hunger.”

Kaplan noted that the body’s drive to return to its defended fat mass is a normal regulatory process designed to prevent starvation and recover from the effects of acute illness and injury.

“Whatever your natural weight is, if you, for example, get sick and lose 10 pounds, after you recover from the illness, your body is going to be overly hungry to get you back to where you started,” he said. “That same process will cause you to regain weight lost from voluntarily dieting, unless you change the defended fat mass. Essentially, the normal process that protects you from starving, ‘protects’ a person with obesity from losing weight and keeping it off.”

Another hormone that plays a role in post-diet weight gain is GLP-1, which modulates insulin sensitivity and regulates blood glucose response.

“With bariatric surgery, both ghrelin and GLP-1 are changed for the better,” Kaplan said.

He noted that the process by which the body regulates fat mass is poorly understood, not only by patients, but by many clinicians as well. He compared the process — and its disruption — to drinking and retaining water.

“We know that gaining water weight isn’t the result of drinking too much water. The body uses it,” he said. “But when you have diseases, that cause edema or ascites, you will actually retain the excess water. People intuitively understand that there’s a regulatory process involved, and that it’s not simply drinking too much water that causes the abnormal fluid accumulation. What people often don't understand is that a similar regulatory process occurs with burning or storing ingested calories.”

Misconceptions about bariatric surgery

Pervasive misunderstandings remain regarding the safety and efficacy of bariatric surgery. According to Kaplan, these misconceptions exist among both the patients and physicians. One area of erroneous thinking pertains to malabsorption and hunger.

“Many people, including myself 20 years ago, thought that surgery worked mechanically either by restricting your ability to eat, or by forcing you to malabsorb the nutrients that you did eat,” he said. “If that were the case, it would be understandable for people to balk at surgery because to force people, against their will, to not eat would be pretty punishing.”

He clarified that even in the earliest papers on surgery, from the 1950s and 1960s, it was demonstrated that bariatric surgery actually decreases hunger and interest in food.

“If surgery restricted what you could eat or caused you to malabsorb what you ate, you’d be a lot hungrier to compensate,” Kaplan said. “The fact that, even from day one, operations that did cause some malabsorption also caused people to feel less hungry demonstrated that the malabsorption was not the primary cause of the associated weight loss. Still, the vast majority of physicians, even surgeons who perform the surgery, think of these procedures either as restrictive, malabsorptive or a combination of the two.”

Morton said bariatric surgery allows food to get to the distal intestine quickly, which signals to the body that the meal is complete.

“You see ghrelin go way down, almost undetectable, which is why many patients for the first few months aren’t hungry at all,” he said. “This gives them the opportunity to change their diet without being pushed by hunger.”

He said GLP-1 often increases after surgery, which may be a mechanism for diabetes remission after the procedure.

“What happens, with both sleeve gastrectomy and gastric bypass, is that food does enter the distal bowel quickly, and that gives the signal for GLP-1 to change,” he said.

Another common misconception is that bariatric surgery is dangerous or at least high risk, either in the short term or the long term.

“That’s another thing that, perhaps people aren’t aware of — how safe these procedures are,” Morton said. “Bariatric surgery is as safe as the removal of a gallbladder or as hip or knee replacement. The long-term benefits are everything from decreasing 5-year mortality by 40% to remission of diabetes at 80%. They’re pretty profound effects.”

Factors involved in obesity

Kaplan said the cause of obesity is a complex combination of environmental, genetic and lifestyle factors, and is related to the greater defended fat mass of these patients.

“It probably has multiple causes, primarily as a result of changes in the modern environment,” he said. “Not everybody develops obesity in this environment, because some people are genetically resistant, but most people are susceptible to the current, obesogenic environment to a greater or lesser degree, which is why two-thirds of us have obesity or are overweight. “

Factors such as certain medications, sleep deprivation, jet lag, night shift work, and chronic stress can all play a role.

“There are multiple factors in the environment that can promote obesity, and they, can all add up,” he said. “It is useful to think of them as causing a pathophysiological disruption in the normal regulation of energy balance.”

Bariatric surgery is useful in that it changes the body’s regulatory target — the defended fat mass. Similar changes in this target can be achieved with some lifestyle modification or drugs that cause weight loss, but with bariatric surgery these changes occur more reliably and are more profound.

“Many of our patients — not a high percentage, but a large number of patients over the years —have lost a lot of weight simply by changing their lifestyles, not eating less, but changing their lifestyles in ways like getting more sleep, exercise, healthier foods. Not less food, healthier food that changes the body’s physiological regulation of fat mass. Surgery induces similar physiological changes, but it does it more powerfully and in a larger proportion of patients than either medications or lifestyle.”

Morton said that in the past, surgery was contraindicated in patients with severe physiological conditions, such as renal or heart failure, but today, such restrictions are limited to patients with severe psychological issues, such as schizophrenia, and active substance abuse.

“It used to be that we would be careful with patients who had severe physiological issues,” he said. “We now operate on patients who are extremely sick. In fact, a lot of patients who are on a transplant list cannot be placed on that list until their BMI is under 35 kg/m². We end up operating on those patients to allow them to get onto the list.

Convincing other specialties

According to Morton, an essential strategy for increasing awareness and use of bariatric surgery is to reach out to other specialties. As immediate past president of the American Society for Metabolic and Bariatric Surgery (ASMBS), Morton has been involved in the Society’s Obesity summit, which is held every September in Chicago.

“It includes more than 30 different specialties, including obstetrics/gynecology, gastroenterology, and orthopedics, and is dedicated to educating these specialties around its consequences,” he said.

Additionally, he said, ASMBS has worked with several of these specialties to develop and clarify clinical guidelines for bariatric surgery.

“The argument that has been made has been one out of necessity. As an example, with orthopedic surgery, once you get a BMI over 40 kg/m², the risk for complications is very high,” Morton said. “What they’ve realized is, just as you wouldn’t operate on someone whose blood pressure is out of control, you shouldn’t operate on a patient whose weight is out of control. You can really improve the outcome of that patient if you get their weight down, improve their blood sugar and get their blood pressure down.”

This kind of information will ultimately be the way to persuade other specialties to reconsider bariatric surgery, Morton said.

“We’re letting other specialties know that here is a way to improve the care they’re already providing,” he said.

Morton said when performed by a Metabolic and Bariatric Surgery Accreditation and Quality Improvement Program-verified surgeon, bariatric surgery is safe and potentially life-changing for patients with obesity who might otherwise never overcome their weight struggles.

“There was a recent study that found that fewer people are dieting now than they were just 10 years ago, even though we have more people with obesity. I think that’s a rational response, because dieting isn’t working for these patients,” he said. “I think what this points out is that we need to find something else that helps. Surgery, in the right hands and for the right patients, can make a very big difference in people’s lives.” – by Jennifer Byrne

Reference:

Fothergill E, et al. Obesity. 2016;doi:10.1002/oby.21538.

For More information:

Lee M. Kaplan, MD, PhD , can be reached at kaplan.lee@mgh.harvard.edu.

John Magaña Morton, MD, MPH can be reached at email: morton@stanford.edu

Disclosures: Kaplan reports consulting relationships with Johnson & Johnson, Medtronic and Novo Nordiak. Morton reports no relevant disclosures.