Bariatric surgery is designed to help obese patients achieve substantial, long-term weight loss that they have been unable to achieve using other methods. The surgery works by restricting the stomach size and (in some cases) limiting the body’s ability to absorb nutrients from food by bypassing a portion of the digestive tract. This operation has evolved through more than half a dozen variations since it was first invented in 1954. Early versions of the procedure were risky and often led to unacceptable side effects such as constant diarrhea, dehydration and liver damage. Older techniques that caused too much malabsorption have largely been abandoned; newer techniques such as the gastric balloon are still in the clinical trial stages. Today, there are four main types of weight-loss surgery performed in the United States.

Gastric Bypass (Roux-en-Y)

The Roux-en-Y is a modern version of the gastric bypass surgery developed in 1967. It can be performed through a long, open incision in the abdomen or laparoscopically via several small incisions. The laparoscopic approach is associated with fewer complications (especially with wound healing), less pain and a shorter recovery. However, patients who are very obese or who have previously undergone abdominal surgery may only be candidates for the open version of the procedure. This is determined on a case-by-case basis, and the criteria may vary between surgeons.

This bariatric surgery is performed using general anesthesia. The surgeon uses a line of staples to create a small pouch out of part of the stomach. This new stomach pouch holds less than an ounce of food (it will stretch a little over time). This limits meal sizes and leads to a feeling of fullness that makes it easier to resist overeating. Gastric bypass also leads to changes in the hormonal signals sent out by the gastrointestinal system, reducing feelings of hunger.

The lower part of the intestine is severed and then surgically attached to an opening in the new stomach pouch. Now, food passes directly from the pouch into a lower segment of the small intestine, “bypassing” part of the digestive system. The more length of intestine bypassed, the less food gets absorbed during digestion. This malabsorption of nutrients can lead to more rapid and effective weight loss. However, there is a tradeoff between high levels of weight loss and the side effects of malabsorption. Most Roux-en-Y procedures bypass only a short segment of the small intestine to limit these side effects.

The large, unused portion of the stomach and the bypassed segment of small intestine aren’t removed from the body entirely. Instead, they are reattached lower on the intestine. This portion of the stomach still produces acids. Letting those gastric juices flow into the lower intestine aids the digestion of food. This approach also means the tissue remains viable. This is important in case of complications that would require a reversal of the procedure.

Pros of Roux-en-Y:

  • This is the most common bariatric surgery. Depending on where you live, it’s relatively easy to find a surgeon with lots of experience performing gastric bypass (an important factor for limiting the risk of complications).
  • Weight loss occurs very quickly after the procedure and tends to be long lasting.
  • Diseases such as type 2 diabetes and high blood pressure that are associated with excess weight may improve rapidly.

Cons of Roux-en-Y:

  • Unpleasant side effects such as “dumping syndrome” are very common. Patients may experience dizziness, nausea, diarrhea, vomiting and other symptoms after eating high-sugar foods.
  • This procedure has a higher 30-day mortality (death) rate than less-invasive procedures such as gastric banding.
  • Calcium and iron deficiencies are an unavoidable side effect requiring lifelong supplementation.
  • The surgery is difficult to reverse and should be considered permanent.

Sleeve Gastrectomy

This bariatric surgery is referred to as a gastric sleeve or vertical sleeve. The surgeon reduces the size of the stomach by about 75 percent. Basically, it becomes a tube rather than a pouch. This reduction restricts food intake and leads to a greater sense of fullness after eating even small amounts of food. The intestines are not modified in this surgery. This procedure may be recommended when only moderate weight loss is needed or if a patient is too high risk for a more invasive bypass surgery.

Pros of sleeve gastrectomy:

  • This procedure has fewer complications and a quicker recovery than gastric bypass.
  • Nutrient malabsorption is not an issue since the intestines are intact.
  • The gastrectomy can be converted into a bypass or duodenal switch later on if needed.

Cons of sleeve gastrectomy:

  • Weight loss occurs more slowly and may not be as substantial as with gastric bypass.
  • The surgery is not reversible.
  • Fewer surgeons have experience performing this new procedure, and the long-term results are unknown.

Biliopancreatic Diversion with Duodenal Switch (BPD-DS)

This weight-loss surgery is often referred to as simply the “duodenal switch” although that is also the name of another, different procedure. In BPD-DS, the stomach is reduced to a tube or sleeve to limit food intake and hunger sensations. The pylorus, which controls the flow of food from the stomach into the intestine is left intact as is the first part of the duodenum (in Roux-en-Y, this part of the intestine is bypassed). A long section of small intestine after the duodenum is removed and reattached further down, close to the beginning of the large intestine (colon).

The duodenum is attached to the remaining length of small intestine. In this way, two different “channels” are created. Digestive juices flow down one, and food moves down the other. The two channels meet up just before the large intestine. Only a small amount of fats and carbohydrates are absorbed in this shortened area where the food and digestive juices finally mix together. This greatly reduces the amount of calories that are available for use by the body.

Pros of BPD-DS:

  • Unlike gastric bypass, this procedure does not cause “dumping syndrome” since the first part of the small intestine is still attached to the stomach.
  • Patients with type 2 diabetes and other “comorbidities” may experience rapid improvement after the surgery.
  • Allowable foods types and quantities are not as restricted as with gastric bypass.
  • Substantial weight loss occurs rapidly and tends to be long lasting.

Cons of BPD-DS:

  • Poor fat absorption leads to deficiencies in vitamins A, D, E and K, requiring lifelong supplementation.
  • Diarrhea and bloating are common long- term side effects.
  • The intestinal portion of the surgery is difficult to reverse and should be considered permanent. The stomach restriction portion of the surgery cannot be reversed.
  • This surgery is highly complex. Finding a skilled surgeon to perform the procedure is difficult.
  • Complications are most common with this type of surgery.
  • It is possible to lose too much weight after this procedure.
  • Gall stones and other gall bladder problems are very common after a duodenal switch. The gall bladder may actually be removed as part of the procedure as a preventive measure.

Gastric Banding

The LAP-BAND® and REALIZE® are the two gastric banding systems approved for use in the United States. These devices work like a belt to create a tightly restricted zone near the top of the stomach. When a patient eats, this pouch fills up quickly. Food passes slowly from the upper part of the stomach to the rest of the stomach. Since patients feel full faster and remain feeling full for longer with a restricted stomach size, patients may significantly reduce their food intake. If a patient eats too much food or eats too quickly, the side effects are very unpleasant. These symptoms can include nausea, stomach cramps, vomiting or severe pain from food blockage. Experiencing immediate side effects from failure to follow the dietary requirements may provide further incentive to stay on track.

The procedure for placing the band is done laparoscopically. The band is placed around the upper part of the stomach. A tube leads from the band to an access port that is placed just under the skin in the abdomen. After a recovery period of four to six weeks, the flexible silicone band is filled with saline solution. The amount of saline can be adjusted to tighten or loosen the band to achieve the desired amount of restriction.

Pros of gastric banding:

  • Patients experience a fast recovery with less pain compared to more invasive bariatric surgery procedures.
  • Banding has a very low mortality rate compared to other bariatric surgeries.
  • The procedure is reversible (barring serious complications).
  • There are no malabsorption issues since the intestines are left intact.
  • The procedure is available to patients with a BMI as low as 30 who have weight-related health problems.

Cons of gastric banding:

  • Weight loss is moderate and may be inadequate to correct severe obesity.
  • Strict patient compliance is required or substantial weight regain is likely to occur.
  • The use of a device introduces additional risks of complications (slippage, erosion into the stomach wall, etc.) Revision surgeries may be needed to fix device malfunction.
  • The devices are fairly new compared to gastric bypass, and the long-term risks are still being evaluated.