A Brief Overview of Metabolic Surgery

Putting the Word “Cure” into the Treatment of Metabolic Disease

Modern medicine has aggressively treated metabolic diseases including type-2 diabetes, hyperlipidemia and hypertension with excellent results in most cases.  These diseases are traditionally thought of as treatable, but not as curable, and interventions have been targeted towards effective lifelong therapy. Other metabolic disease, in particular severe obesity, has suffered from a failure of medical intervention to result in effective treatment.  Long-term weight loss and fitness will almost always improve the results of medical treatment and, in some cases, eliminate these metabolic diseases altogether. But, aside from the rare individuals that succeed in major lifestyle change, medical treatment never provides a “cure.”

The Cost of Metabolic Disease

The medical regimens required to treat metabolic diseases can be very expensive, and add up to considerable sums over a lifetime.  The annual direct cost of treating the 67 million Americans (CDC, 2011) with hypertension was estimated at $47.5 billion, or about $710 per patient, adding up to more than $21,000 over thirty years.  Direct medical costs for treating the 25.8 million Americans (2011) for diabetes is estimated at $176 billion, or $6,800 annually per patient, or over $200,000 per patient over 30 years.  And, as leading causes for stroke, heart failure, heart attack, kidney disease, blindness and dementia, the overall cost of metabolic disease adds up.  Taken as  a group, metabolic disease exacts a huge toll on our healthcare system in terms of physician time, direct medical cost, lost productivity and patient disability.

The New Role for Surgery

Metabolic surgery is the subspecialty of surgery that addresses metabolic disease as potentially curable.  Historically, metabolic surgery has focused on obesity and operations have been primarily targeted towards resolving severe obesity. The first reason for this was that severe obesity is highly recalcitrant to all other medical intervention, and the second reason was that the impact of these operations on long-term weight loss was dramatic and well documented.  Over the past two decades, however, it has become apparent that the operations used in bariatric surgery have a significant positive impact on several other metabolic disorders.  In fact, the success for resolving hypertension, hyperlipidemia and type-2 diabetes through bariatric operations has resulted in new areas of research on the role of the gastrointestinal tract as a metabolic organ system.

The most exciting clinical realization has been that performing gastrointestinal surgery to treat metabolic disease can, in fact, result in a cure.  The potential for metabolic operations to actually cure these diseases is now an irrefutable fact, and has resulted in a paradigm shift where certain metabolic diseases are no longer considered to be simply treatable, but are now known to be potentially curable.

Published in the Journal of the American Medical Association in 2004, a meta-analysis of 22,049 patients that had undergone traditional bariatric surgery showed an overall 61% sustained excess body weight loss.  In terms of other metabolic disease the study showed a 76.8% resolution of type-2 diabetes, a 61.7% resolution of hypertension, and a 79.3% improvement in hyperlipidemia.  In a more recent study examining 23,000 patients with metabolic syndrome that underwent bariatric surgery, 36%, 50% and 35% had complete remission of hypertension, diabetes and dyslipidemia, respectively.

Successful resolution of metabolic disease after metabolic surgery is far from 100%.  Nevertheless, the fact that diseases previously thought to be only treatable are now known to be potentially curable is incredibly important.  Patients suffering from these disease processes can now be counseled that there is an opportunity for cure, and if they meet the criteria for surgical therapy, they need to be made aware of the option for surgical treatment of their disease.

Who Qualifies for Metabolic Surgery?

The National Institutes of Health (NIH) published guidelines for bariatric surgery after a 1991 consensus conference.   These guidelines are currently published on their website with a disclaimer (reprinted below) stating that the guidelines are outdated.  Despite advancements over the past 25 years resulting in safer bariatric procedures (decreased risk) and a higher level of success (improved benefit), Medicare and commercial insurers still refer to the 1991 guidelines when authorizing use a surgery to treat obesity and metabolic disease.

The 1991 NIH guidelines were based on benefit-versus-risk, and are fairly simple; “Patients whose BMI exceeds 40 are potential candidates for surgery if they strongly desire substantial weight loss, because obesity severely impairs the quality of their lives.  In certain instances less severely obese patients (with BMIs between 35 and 40) also may be considered for surgery. Included in this category are patients with high-risk comorbid conditions” and patients with “obesity-induced physical problems interfering with lifestyle (e.g., joint disease treatable but for the obesity, or body size problems precluding or severely interfering with employment, family function, and ambulation).”

Following these 1991 guidelines, the insurance industry will generally authorize patients to undergo bariatric surgery if they have a BMI>40, or a BMI = 35-40 with significant weight-related disease or disability.

More up-to-date indications for surgery take into account the preponderance of scientific data showing essentially all patients with a BMI greater than 35 to have a markedly increased risk for multiple disease processes, including diabetes, heart disease and cancer, as well a substantially increased prevalence of physical disability.  Modern indications for surgery also acknowledge extensive data that demonstrate the health risks of having a body mass index of just 30.  In fact, the health risk for a BMI of 30 or greater (defined medically as the threshold for obesity) is so well accepted that the FDA approved the Lap-Band device for treating patients with a BMI as low as 30.

From the published statement on the FDA website (updated 9/6/2013)

“The LAP-BAND® System is used for weight loss in obese adults who have a Body Mass Index (BMI) of 30-40, with one or more obesity-related medical conditions (such as Type II diabetes and hypertension), and when non-surgical weight loss methods (such as supervised diet, exercise, and behavior modification) have not been successful.”

The take-home message is that, based on up-to-date data and the safety of modern surgical procedures, it is reasonable to consider weight-loss surgery for any patient with a BMI>35.  It is also reasonable to consider selected individuals with a BMI between 30 and 35 who have failed at long-term weight loss and complain of a decreased quality of life, or who suffer from significant weight-related medical disease.

(Any patient that meets these criteria may be referred for surgical consideration.  The staff at The N.E.W. Program will handle the authorization process for surgery, and will explain the insurance criteria to all callers prior to scheduling them for an appointment. The N.E.W. Program staff are highly experienced at helping patients with insurance questions pertaining to surgery.)

Education: The First Step in the Metabolic Surgery Process

The first step in the metabolic surgery process is education of the patient and a reality awareness check.   Metabolic surgery has a high degree of success, and if done correctly has a low surgical risk.  However, like most medical treatments, compliance on the part of the patient is key to obtaining the best result, and because the only reasonable goal for someone undergoing metabolic surgery is to achieve long-term or permanent success, up-front understanding of the patient role in the surgical treatment process is mandatory.

All patients need to be explained that maximum long-term success is dependent on lifestyle changes that they should find to be far easier to achieve with the help provided through surgery.  However, these changes need to be desired and truly pursued if they are to become a reality in a patient’s life, and all patients need to have it clear in their mind that, for long-term success, healthy changes in eating behavior need to be embraced.  The simple dietary guidelines developed at The N.E.W. Program, featured in this newsletter, do not represent a diet and are not restrictive like so many “diet” programs, but are still key to long-term success.  An important thing for patients to understand is that healthy eating actually feels better, is enjoyable, and gives people a feeling of “more energy.”  Another reality is that healthy eating takes practice by everyone, whether a person has been overweight or not.  The end result, however, is that patients who use the surgical procedure to assist them in improving their diet, and use the weight loss as an opportunity to exercise, can obtain permanent weight loss, dramatic metabolic improvement, and big rewards in an improved quality of life.

Preparing for Metabolic Surgery

Once a patient comes in for their initial consultation for metabolic surgery, they are provided with educational materials and then meet with the surgeon, the bariatric internist, the dietician and the clinical psychologist.  A thorough medical evaluation is completed and specific testing is scheduled.  Patients that meet the physical qualifications for surgery are more likely to have serious, undiagnosed medical disease that not only affects their current health but also may result in increased risks for surgery.  Examples include undiagnosed diabetes, obstructive sleep apnea, poorly controlled hypertension and non-alcoholic fatty liver disease.  And the majority of patients already have undiagnosed malnutrition including deficiencies in iron, vitamin D, calcium, B vitamins and other micronutrients **.  Accurately identifying a patient’s weight-related medical disease is a critical step toward enabling the patient to prepare for a safe surgery.

In 2001 physicians at The N.E.W. Program were the first to routinely place patients on a pre-operative very low-calorie diet (VLCD) for just two weeks to decrease liver size.  We subsequently published a study on obesity-induced liver enlargement (hepatomegally), and demonstrated our ability to decrease liver size by over 25% prior to surgery, improving our patient’s nutritional status and resolving hepatomegally.  Many surgeons had previously reported that the single biggest anatomic factor resulting in inability to perform safe laparoscopic surgery for obesity was hepatomegally — and now many surgeons use a 2-week diet in preparation for surgery, mainly to reduce liver size.  Other interventions that enable better preparation for surgery include treatment for uncontrolled heart disease and severe sleep apnea as well as improvement in nutritional status.  Once patients are medically optimized by our bariatric team, and follow the pre-operative diet, they are ready for surgery.

The Surgical Experience

Patients are asked to arrive at the hospital 2-3 hours in advance of their scheduled procedure.  This enables the hospital staff to get the patient ready for surgery in a comfortable environment.  Most bariatric surgical procedures involve about 2 hours in the operating room; 30 minutes of preparation before surgery and 30 minutes after, and approximately one hour of actual operating time.  Patients spend an average of one hour in the recovery room under the close observation of experienced recovery room nurses, and then are admitted to the surgical ward.  At The N.E.W. Program less than 1 out of 20 patients are admitted to the intensive care unit after surgery, and this is mainly as a precaution in order to better monitor certain patients who have fragile medical conditions prior to surgery.  The typical hospital stay is one or two nights.  Patients are encouraged to be out of bed on the day of surgery, and are typically walking in the surgery ward and tolerating a liquid diet the next day.

At-home recovery involves light activity for one week, and by 10 days after surgery most patients are back to regular activity and may return to work.  A one-month staged eating program involves a two week high protein liquid diet, followed by a two week diet of soft foods, allowing the surgery time to heal.  After 4 weeks patients are usually back to regular food but are required to eat more slowly and to chew their food well.  The N.E.W. Program’s Basic Nutritional Guidelines© are then used to help guide patients in practicing a healthy eating pattern for the rest of their lives.  As the weight comes off, increased activity and exercise is critical for improving body composition and metabolism, maximizing weight loss, and maintaining health and fitness.

What are the Standard Metabolic Surgical Procedures?

Bypass Operations:

A very brief history of bariatric surgery begins 60 years ago in 1953 with Dr. Victor Henrikson of Gothenburg, Sweden who performed an intestinal resection to treat obesity and Dr. Richard Varco, at the University of Minnesota, who performed the world’s first intestinal bypass to treat obesity.  For the next 25 years operations for obesity consisted primarily of malabsorption operations, specifically various kinds of intestinal bypasses; the jejuno-ileal bypass being the most common.  These operations resulted in a high degree of malnutrition and fell out of favor more than thirty years ago.  In 1967 a less malabsorptive operation was invented by Dr. Mason at the University of Iowa, the Gastric Bypass, and this operation has been improved over the last 45 years to the current Laparoscopic Gastric Bypass which is still the gold standard in bariatric surgery.  Around 1980, the gastric bypass was changed to the roux-en-Y gastric bypass, and this minimized risk of GERD which had been experienced with the initial procedure. However, as a result of intestinal bypass, the term “bypass” came to falsely represent operations with a high risk of severe malnutrition.  The gastric bypass involves only a limited intestinal bypass, mainly bypassing the stomach, whereas operations that carry the higher risk for malnutrition are those that involve significant bypass of the small intestine.  Two operations, the Biliopancreatic Diversion and the Duodenal Switch, both involving significant intestinal bypass, are still used for super morbid obesity (BMI>60) by some surgeons.  At The N.E.W. Program, the only bypass operation performed is the Gastric Bypass.

Restrictive Operations:

Around 1979 Dr. Mason also invented the gastroplasty, which carried no risk for malabsorption and was called a “restrictive operation.” Various forms of the gastroplasty (also called stomach stapling) were used for about 20 years, but despite successful weight loss the complications including chronic vomiting were high and the operation fell out of favor.  In the 1990s an improved restrictive operation, adjustable gastric banding, was started in Europe and in 2001 the FDA approved the Lap-Band for use in the United States.  The Lap-Band is a very safe operation, and surged in popularity for almost ten years, but it’s popularity has declined due the introduction of a newer restrictive operation with better results, the Vertical Sleeve Gastrectomy.  The “sleeve” procedure has weight loss comparable to the gastric bypass with no intestinal bypass.

Currently, the most common operations in the world are the gastric bypass, the sleeve gastrectomy and the Lap-Band, all performed using minimally invasive surgery, or laparoscopy.  The graph below demonstrates some of the differences between these operations. (Data specific to The N.E.W. Program)

ProcedureGastric BypassSleeve GastrectomyLap-Band
Length of Operation1 hour50 minutes45 minutes
Average Hospital Stay1-to-2 daysOutpatient-to-2 daysOutpatient-to-1 day
Avg Weight Loss (Typical Range)75% of excess (50-100%)70% of excess (40-100%)50% of excess (0-100%)
Nutritional IssuesUncommonRareRare

Observations on Metabolic Surgery and Future Directions

Although it may seem like the positive effect metabolic surgery has on diabetes, hypertension and other disease is a recent discovery, the fact is that the use of surgery to treat metabolic diseases other than obesity was being studied in the 1960s.  As the evidence grew for surgery as a primary treatment for high cholesterol, high triglycerides and type-2 diabetes, the effect of different operations was identified.  Due mainly to the dramatic improvement in diabetes and high cholesterol after gastric bypass, the important role of hormones produced by the stomach and small intestine in the regulation of insulin, blood sugar and metabolism has become apparent. These observations have now culminated in intensive research into the use of surgery specifically to treat metabolic disease, particularly as a treatment for diabetes.

In September 2008 the first World Congress on Interventional Therapies for Type-2 Diabetes was held in New York.  The excitement at this meeting focused on evidence that surgery could be performed safely, on non-obese individuals, specifically to resolve diabetes without weight loss.  Since then studies on surgical procedures to treat type-2 diabetes are being performed throughout the world, including a large study on individuals with BMI = 26-35 being conducted at the Cornell University.

With an improved understanding of the role of the gastrointestinal tract, and it’s importance in controlling cholesterol, triglycerides, insulin and our metabolism in general, the field of metabolic surgery has evolved.  Understanding modern metabolic surgery is important in the treatment of metabolic disease, not only to improve these conditions, but sometimes to provide a cure.


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Buchwald H, Varco RL. lleal bypass in patients with hypercholesterolemia and atherosclerosis: Preliminary report on therapeutic potential. JAMA 1966; 196:627-630

Pories WJ. Why does the gastric bypass control type 2 diabetes mellitus? Obes Surg. 1992;2:303–313

Forgacs S, Halmos T. Improvement of glucose tolerance in diabetics following gastrectomy [in German]. Z Gastroenterol. 1973;11:293–296

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William B Inabnet III, MD, FACS, Deborah A Winegar, PhD, Bintu Sherif, MS, Michael G Sarr, MD, FACS

Early Outcomes of Bariatric Surgery in Patients with Metabolic Syndrome: An Analysis of the Bariatric Outcomes Longitudinal Database. J Am Coll Surg, 2012

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Disclaimer on the NIH website: http://consensus.nih.gov/1991/1991gisurgeryobesity084html.htm

“This statement is more than five years old and is provided solely for historical purposes. Due to the cumulative nature of medical research, new knowledge has inevitably accumulated in this subject area in the time since the statement was initially prepared. Thus some of the material is likely to be out of date, and at worst simply wrong.”

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