Types of Weight Loss Surgery
Surgery for weight loss has been around for almost 60 years, beginning in the 1950’s with the jejuno-ileal bypass (intestinal bypass). Since that time, many different types of procedures have been developed and tested. Most have fallen by the wayside, but a few have proven safe and successful.
There is always something new on the horizon with newer modifications and innovations constantly under evaluation. This combination of a long and often poorly understood history, along with the progressive innovation, creates a complex and often confusing picture for patients and healthcare workers alike. However, at the current time, three different procedures encompass the vast majority of weight loss surgery performed in the world: the Roux-en-y gastric bypass, the laparoscopic adjustable gastric band, and vertical sleeve gastrectomy. Each of these is detailed below.
The Roux-en-y gastric bypass is the most popular weight loss surgery procedure in North America, representing the majority of bariatric surgery performed over the last 30 years. It has been around since 1967 and is considered by many to be the “gold standard”. As such, it has been studied, modified, and refined, and now represents a safe, acceptable and effective means of treating morbid obesity. 90% of those who undergo this procedure with achieve successful weight loss (defined as greater than 50% excess weight loss).
On average, weight loss is around 70% within two years. For example, if one weighs 250 pounds with an ideal body weight of 150 pounds, excess weight is 100 pounds. Expected weight loss would be 70 pounds, resulting in a final weight of 180 pounds. This profound and consistent weight loss is achieved by utilizing all four mechanisms described above.
First, restriction is achieved by creating a very small pouch, about the size of a golf ball or egg. This reduces the size of the stomach by over 90%. As such, a feeling of fullness or “satiety” is achieved with only a few bites of food.
In addition, a moderate amount of malabsorption occurs because of the intestinal reconstruction performed when creating the outflow for the pouch. A segment of the small intestine is “bypassed” because the inflow of bile and pancreatic enzymes comes in 100-150 cm downstream from the pouch. Therefore, after food empties the pouch, it is not broken down to be absorbed until it passes this point. Over the years, the optimal amount of bypassed intestine has been determined such that the malabsorption effect aids with weight loss but is not so extensive that it causes malnutrition. It has also been noted that this malabsorption effect is most profound within the first 12-18 months, and most believe that the body accommodates to this new anatomy, creating a lesser effect long-term.
The third way this procedure affects weight loss is via hormonal mechanisms. Several gastrointestinal hormones (GLP-1, PYY, Grehlin) are affected when the stomach is divided and the intestine is re-routed. This effect is poorly understood, but results in a profound decrease in hunger. Indeed, the vast majority of our patients report that they are “just not hungry” after this procedure. This assists in the ability to maintain a very low caloric input necessary to affect profound and long lasting weight loss. Many experts believe this to be the most important mechanism by which gastric bypass is effective long-term.
Further, certain foods, particularly sweets and starches, will cause unpleasant side-effects, such as cramping, nausea, diarrhea, sweating and light headedness. This is called dumping syndrome and occurs because food now empties straight into the intestine rather than being diluted and processed in the stomach. This intestine is not designed to handle such a load of carbohydrates and the body reacts by secreting a large amount of fluid into the intestine in an effort to dilute the food. As a result, sweets and junk food hold no attraction for the vast majority of those who undergo this operation. This greatly helps in maintaining disciplined dietary habits.
Results of Gastric Bypass
The above mechanisms combine to produce a powerful tool to achieve profound and long-term weight loss. Studies show that 90% of those undergoing this procedure lose about 70% of their excess weight. This is maintained long-term in around 80% of people. Several large studies have shown that over 90% of comorbid conditions associated with morbid obesity are either improved or resolve in those undergoing gastric bypass.
It is the rule, rather than the exception to see diseases such as diabetes, hypertension, sleep apnea and hyperlipidemia completely resolve within a few months of surgery However, it is imperative that this procedure be accompanied by a steadfast commitment to discipline dietary and exercise habits in order to achieve long-term success. Part of this discipline includes regularly taking certain supplements that the body now absorbs less efficiently. Because of the alteration of the GI tract, certain nutrients such as iron, calcium and vitamin B12 are absorbed less efficiently. Over the years, one may develop problems such as anemia and osteoporosis. These issues are relatively easily avoided with a regimen of routine vitamin and calcium replacement. Annual follow-up to check these levels is recommended for anyone undergoing gastric bypass.
Adjustable Gastric Banding
Although gastric banding has been around since the 1970s, it has gained popularity in the United States only in the last ten years. It was first evaluated primarily in Europe and Scandinavia almost 40 years ago. At that time, the results were not as good as gastric bypass or vertical banded gastroplasty (VBG), so it fell out of favor.
Interest rose again in the early 90s when an inflatable variant was developed, and in 1993 the first laparoscopic adjustable gastric band (LAGB) placement was performed. This was evaluated in Europe and Australia throughout the 1990s and popularity grew. In 2001, the FDA approved laparoscopic adjustable banding in the United States. A massive marketing campaign by Inamed, the maker of the LAP-BAND® system, has made this device a household name in the U.S. over the last ten years. Currently, there are two laparoscopic LAGB devices available, the above stated LAP-BAND® system and the Realize® band, produced by Ethicon, a subsidiary of Johnson & Johnson.
The band is placed just below the junction of the stomach and esophagus, thus creating a small pouch above it, similar in size to the pouch created with the gastric bypass. The band is lined with balloons on its internal circumference. These balloons are attached to a catheter that leads to an infusion port which is implanted underneath the skin on the abdominal wall. The balloons are inflated by accessing the port (through the skin) and injecting saline. This fills the balloons and therefore the band tightens around the stomach, decreasing the size of the outflow (or stoma) between the pouch and the rest of the stomach.
In essence, by placing a band we create a small gastric pouch with an adjustable outflow. If the band is fully inflated, it will likely be too tight to allow any food to pass. Likewise, if the band is completely deflated, food passes without any difficulty whatsoever. As such, the band utilizes restriction as the singular mechanism for weight loss. Generally there is no decreased hunger, nor will there be any dumping or malabsorptive effect, as once food passes the band it progresses normally through the GI tract.
Multiple adjustments (or “fills”) are made, starting at about six weeks from surgery. These are performed at regular intervals, usually every 3-4 weeks, injecting a little more saline each time until the band is the right volume. This process is customized to each patient, as the final volume may vary significantly between individuals. Usually 4-6 adjustments are made in the first twelve months, with regular maintenance required long-term. Judicious and long-term follow up is therefore essential to success with the laparoscopic adjustable band.
The weight loss experience with the LAGB has been found to be generally less robust and more variable than that compared to gastric bypass. Average weight loss is about 40-60%, and this is experienced in about half of individuals. In other words, about 50% of people lose about 50% of their excess weight. The majority of the remainder will lost 20-30% of their excess weight and approximately 2-5% will lose no weight or actually gain weight. On the other hand, up to 10% may lose over 60% of their excess weight.
Resolution of medical problems associated with obesity is blunted, as diseases like diabetes are cured in about 50%, compared to 85% with gastric bypass. It has also been shown that those undergoing a LAGB will have a higher rate of reoperation, as up to 15-25% of bands placed may be removed at some point for a problem or complication.
However, gastric banding does confer several advantages. It is a lesser extensive operation on the GI tract, recovery time is a little shorter and it is “sort of” reversible, if need be. Also, it can be adjusted at any time and there is less chance of certain nutritional problems, such as mineral (iron and calcium) and vitamin (B12) deficiency. The lack of dumping, malabsorption and hormonal changes make it such that it is easier to “cheat”, which is why most believe that the results are as stated above. This underscores the fact that to meet your goals with weight loss surgery, and especially LAGB, it is imperative that one have and pursue a disciplined strategy for success. This includes specific dietary habits and a firm commitment to a healthy, active lifestyle along with long-term follow up with your bariatric surgeon.
Vertical sleeve gastrectomy (VSG) is a relatively new procedure, first developed in 1993. Its popularity increased in 2001 when it was proposed as a first stage of a laparoscopic biliopancreatic diversion with duodenal switch (BPD-DS). At that time, BPD-DS was typically performed “open” (with an incision) and some centers were studying the possibility of performing it via minimally invasive technique.
As the procedure was rather complex, it was postulated that it would be safer to perform the procedure in stages, the first one being the laparoscopic sleeve gastrectomy. Plans were then made to complete the procedure several months later after weight loss had created a safer surgical environment. However, it was found that a certain segment of individuals lost adequate weight with the sleeve alone and didn’t require the second stage.
In 2005, studies on laparoscopic VSG performed as a standalone procedure were conducted. By 2010, data on over 2,500 patients had been compiled, showing a weight loss of 33-85%, with an average of 60% excess weight loss at five years. Based on this, several societies and insurance companies agreed that this was an acceptable surgical procedure for weight loss. It is therefore a covered benefit for some companies, but may still be considered investigational by others.
The VSG is an operation that involves limiting the amount of food taken in by removing about 75%-85% of the stomach. This is done by cutting away a large portion of the stomach and thus creating a thin tube or sleeve that is about the size of a banana. As such, there is no modification of the remainder of the gastrointestinal tract.
It affects weight loss by utilizing two of the four mechanisms for surgical weight loss.
- It produces restriction as the stomach volume is severely reduced. The sleeve is approximately three times the size of the gastric pouch created with the band or gastric bypass, but remains markedly smaller than the native stomach. The part of the stomach removed is critical for two reasons. First, this portion, called the fundus, is the part of the stomach that functions to expand with a meal. The sleeve which remains is thicker and more muscular and therefore not only smaller, but less compliant. It creates an earlier feeling of “satiety” or satisfaction with eating smaller meals.
- The removed portion is the part of the stomach which is responsible for creating ghrelin, a hormone that triggers the hunger center in the brain. As a result, about 75% of patients have a significantly reduced sensation of hunger. This is compared to an approximately 90% reduction in hunger in those undergoing gastric bypass, as this hormonal mechanism although present, is a little less robust. Because the gastrointestinal tract is not disturbed, there is no malabsorption nor will most experience dumping syndrome.
As stated above, the VSG is a relatively new procedure and thus far, minimal data exists as to its effectiveness beyond five years. However, the results so far reveal weight loss ranging from 35-85%, with an average of 60% in excess weight loss at this juncture.
It is important to understand that the long-term results are unclear. The minimal preliminary data reveals weight loss at 7-8 years averaging about 55%. As weight loss is seen to be somewhere between gastric bypass (70%) and gastric band (50%), so is reduction in medical problems. The best example of this is diabetes, where an average of 60% resolution is experienced compared to 85% with gastric bypass (GBP) and 50% with LAGB.
Notably, the potential for vitamin and mineral deficiency is less than that with gastric bypass, as normal flow of food remains intact. However, it is important to know several facts when considering this procedure for weight loss.
- As stated, the long-term results are not known.
- The procedure was conceived as the first of two stages and some patients will lose inadequate weight and therefore could be considered for (or need) a second stage procedure to achieve desired results. At the current time, the recommended second stage procedure is conversion to a gastric bypass.
- The sleeve gastrectomy is the only truly irreversible weight loss surgery.
- Although considered by many to be a “safer” operation than the gastric bypass, complications such as leaking or bleeding are actually higher after a sleeve gastrectomy. Overall surgical mortality rates are identical to gastric bypass at .2%.
With the above caveats understood, we believe that VSG is an excellent operation for surgical weight loss. Certain aspects will continue to be refined as the body of data grows and it will remain in our bariatric surgery armamentarium for the foreseeable future.
How To Calculate Percent of Excess Weight Loss
When describing the results of efforts at weight loss, we use the term “percent excess weight loss” (% EWL). This is calculated by dividing the actual weight loss by the amount of excess body weight for that individual. As a result, we can calculate a percentage that will be comparable between people with different body weights.
% EWL = Weight Loss / Excess Body Weight x 100
For example, suppose an individual is 5’6” and 250 pounds. At this height, ideal body weight is 150 pounds, therefore she has 100 pounds excess body weight. If she loses 50 pounds, then % EWL is 50/100 x 100 or 50%. If she loses 75 pounds, her % EWL is 75/100 x 100 or 75%.