Weight Loss Surgery Procedures

Gastric Bypass

Gastric bypass, also known as Roux-en-Y gastric bypass, is the most common and successful weight loss surgery in the US, with acceptable risks and side-effects. In this procedure, the surgeon creates a small stomach pouch in the top of the stomach that forms the new stomach and restricts food intake. The surgeon then creates a small opening, or stoma, in the pouch and attaches that opening to a section of the small intestine, which forms the "bypass" of most of the stomach and a small section of the intestine.

With a smaller stomach, patients feel full sooner when eating. Reduced amounts of food, along with calories and nutrients, can be absorbed. This procedure also limits patients' tolerance for fatty and sweet foods.

This surgery can be performed laparoscopically, and requires five or six small abdominal incisions rather than the 6-8 inch incision employed in the open gastric bypass.

With this procedure, most patients lose about 50-70% of their excess body fat within 12-18 months after surgery. About 50% of excess weight loss lasts about 10 years. About 80% of obese patients with diabetes find that with this surgery their diabetes resolves rapidly, sometimes within days or a few weeks.

Patients undergoing gastric bypass must take vitamin and mineral supplements for life, make sure to eat adequate protein, and avoid excess sweets and fats. One of the risks of gastric bypass is "dumping syndrome" or reactive low blood sugar – feelings of nausea, cold sweats, faintness, diarrhea, and palpitations, which can occur after eating a meal high in simple carbohydrates.

Duodenal Switch

Duodenal Switch is a procedure that entails removing about 60% of the stomach, giving the stomach a tube-like shape. Surgeons then divide the lower intestine further downstream with the gastric bypass, resulting in more of the intestine being bypassed.

Patients who receive this surgery can eat larger-sized portions than with the gastric bypass or adjustable gastric banding (see below), and produces reliable, long-term weight loss. This procedure reduces the absorption of dietary fat by about 70%, which not only causes significant weight loss, but enables patients to reduce their cholesterol and triglyceride levels.

This procedure enables most patients to lose 60-80% of their excess body weight over about 2 years, trials have demonstrated, and weight loss lasts beyond 10 years.

While individuals who undergo this procedure may be able to eat more food than with other surgeries, they should still avoid large quantities of fat, sugar, and frequent snacking. Patients having duodenal switch surgery should eat sufficient protein and take vitamins and mineral supplements for life.

Sleeve Gastrectomy

Sleeve Gastrectomy is a new, minimally invasive procedure that is performed in under an hour and carries with it a reduced chance of leakage, infection, and bleeding, compared to other weight loss surgeries. It restricts food intake by the removal of about 60% of the stomach, so that the stomach is reduced to the shape of a tube, or "sleeve."

Surgeons usually perform this procedure on patients who are either super-obese or who are high-risk, with the intention of performing a second surgery at a subsequent time. The second procedure is usually either a gastric bypass or duodenal switch.

This procedure, when part of a combination approach, greatly reduces the risks of bariatric surgery for certain patients, even though it entails two surgeries.

Patients undergoing this procedure usually lose 30-50% of their excess body weight over a 6-12 month period. The timing of the second procedure will depend on the amount of weight lost, and usually take place 6-18 months after the first surgery.

When performed alone, the sleeve gastrectomy not only restricts gastric volume, but decreases the produce of the hormone, ghrelin, which is produced by the left side of the stomach and signals satiety. This procedure reduces feelings of hunger and can result in weight loss that compare favorably in some patients to gastric bypass.

Patients having sleeve gastrectomy should eat smaller amounts of food and avoid large quantities of fat and sugar. They will need to eat sufficient protein, and take multivitamin supplements daily.

Adjustable Gastric Banding (Lap-Band)

Adjustable Gastric Banding has been performed overseas for over a decade and was approved in the US in 2001. It is much less invasive than other procedures, because neither the stomach nor intestine is cut. Surgeons place an adjustable band around the upper part of the stomach to create a small pouch above the band. By adding fluid to the band after recovery from surgery, the surgeon adjusts the size of the opening between the smaller, upper pouch and the remaining lower portion of the stomach.

The tightness of the band opening controls passage of food between the two parts of the stomach, and helps patients feel full after eating. This feeling of fullness lasts significantly longer than it would without the band. The surgeon works closely with each patient to tailor the adjustment to his or her individual needs.

Losing weight after adjustable gastric band surgery is more gradual than with gastric bypass. Most patients undergoing this procedure lose 40-60% of their excess weight within two years of surgery. The amount of weight lost depends on adapting new eating habits and maintaining them, regular exercise, and follow-up with our staff.

Patients undergoing adjustable gastric banding surgery should eat three meals a day, one or two planned snacks, and take a multivitamin. Food should be chewed thoroughly and swallowed slowly. It is best to wait at least one hour between eating and drinking. Foods to avoid include sweets and high calorie drinks. After this procedure, some individuals are not able to tolerate red meat, white rice, fresh bread, and fibrous foods.

Multi-Step Operations (Laparoscopic Staged Procedures)

Patients whose body shape makes their surgery more technically difficult may benefit from a two-stage, laparoscopic procedure. In such cases, we perform a multi-step operation, such as a gastric bypass or duodenal switch, in two simpler and safer operations.

The first stage consists of a sleeve gastrectomy, in which the left side of the stomach is surgically removed to substantially reduce its size, enabling the patient to lose 80-100 pounds or more. This makes the second-stage operation, which is usually performed 8-12 months later, substantially safer.

In the second stage, the "sleeve" stomach is converted into a formal gastric bypass or duodenal switch, which allows additional weight loss, and provides a more permanent result than sleeve gastrectomy alone. Both stages are performed laparoscopically.

Revisional Surgery

Revisional surgery may be an option for patients who have already undergone a procedure and need another one to either repair the first one, or for those who have gained weight or have not lost sufficient weight.

In about 50% of cases, vertical banded gastroplasty, or "stomach stapling" fails, resulting in inadequate weight loss. Staple erosion in more recent cases may cause chronic inflammation, ulcers, and infection. This is one major reason that our surgeon use absorbable sutures instead of staples to perform intestinal attachments to the stomach.

In other cases, a patient's original gastric bypass may become ineffective when the small pouch and opening to the intestine which the surgeon created stretches, allowing more food into the intestine, leading to weight gain. Such stretching of tissue may occur because of overeating, or from the healed tissue stretching naturally.

Sometimes scar tissue develops during the healing process after a first surgery which can make a revision surgery and healing more difficult. Our surgeons have created procedures that lower the risk of a second surgery.

Most often, patients need a revision surgery to convert an older weight loss procedure to a more modern, effective one, such as the Roux-en-Y gastric bypass with a duodenal switch.


Center for Obesity Surgery, NewYork-Presbyterian/Columbia

Phone: 212-305-4000

Weight Loss Surgery Program, NewYork-Presbyterian/Weill Cornell

Phone: 212-746-5294