Gastric Bypass Surgery

Gastric bypass surgery is a type of bariatric surgery that treats morbid obesity and obesity related health problems through food restriction and malabsorption. It is the most common type of bariatric surgery performed in the United States and has helped many morbidly obese individuals achieve substantial and lasting weight loss and an improvement in their overall health and quality of life. Although the first gastric bypass surgery was performed more than 30 years ago, it’s success rate through the years has kept it the benchmark by which all other bariatric options are compared.

Overview of Gastric Bypass Surgery

Gastric bypass surgery is a general term used to describe the various methods of bariatric surgery that involve:

  • Food restriction: dividing the stomach to create a smaller upper food pouch
  • Food malabsorption: rerouting the small intestine to alter digestion

Gastric bypass procedures have been performed since the late 1960's. The earliest procedures used a “loop” configuration to alter digestion, but this approach was abandoned in favor of other methods. The Roux-en-Y (RNY) gastric bypass surgery, which is currently the most common type of gastric bypass surgery, was first performed in 1967 through open surgery, and uses a “Y” configuration in rerouting the intestines. The first laparoscopic Roux-en-Y gastric bypass was performed in 1993.

  • The various gastric bypass procedures are similar in the respect that they all reduce the functional volume of the stomach and alter the body’s response to food.

In RNY gastric bypass procedures, a smaller stomach pouch is formed in the upper portion of the stomach and a new stomach outlet (stoma) is formed. After the intestine is divided, the lower intestine is connected to the new stomach outlet. The remaining “remnant” lower stomach, the natural stomach outlet (pyloric valve), and the upper portion of the small intestine are all bypassed. The length of either section of the intestine can be made shorter or longer to affect the levels of absorption.

  • The primary difference between the specific gastric bypass procedures is the way in which the intestines are rerouted.

The most popular version of RNY gastric bypass surgery is the proximal (nearer to) gastric bypass, also called short limb Roux-en-Y gastric bypass. A modified version is the distal (farther away) gastric bypass or long limb Roux-en-Y gastric bypass surgery, which moves the intestinal Y-connection further down the small intestine in order to further reduce food absorption.

Another gastric bypass procedure that has been gaining attention is the biliopancreatic diversion with duodenal switch (BPD-DS) surgery. The procedure restricts eating less than the RNY, but bypasses a larger portion of the intestines causing greater malabsorption. Because it is a very complex operation with a high malabsorptive aspect, the duodenal switch is primarily recommended only for very obese individuals who have a BMI of 50 or higher.

Gastric bypass surgery may be performed through either open surgery or laparoscopic surgery, depending on the individual patient’s anatomy. Gastric bypass surgery was initially performed through open surgery, but the development of laparoscopic techniques paved the way for the first laparoscopic RNY gastric bypass surgery in 1993. Laparoscopic surgery is performed through small incisions using special tools and does not require opening the entire abdominal wall. The benefit is a quicker recovery and less pain than associated with open surgery.

Advantages of Gastric Bypass Surgery

  • Rapid weight loss in the first six months following surgery
  • Limits the amount of food that can be eaten at any one time
  • Reduces the amount of food (calories) that are absorbed by the body
  • Controls the intake of high-calorie sweets and fats due to dumping syndrome
  • Resolves or improves many obesity related health conditions, including type 2 diabetes

Disadvantages of Gastric Bypass Surgery

  • Surgical risk from operating on stomach and intestines, including infection, suture leaks, and blood clots
  • Changes to the digestive tract may cause ulcers, bowel obstruction, or reflux
  • Lifetime need for nutritional supplements to avoid vitamin and mineral deficiencies which can lead to serious health conditions, including metabolic bone disease or anemia
  • Dumping syndrome, which causes nausea and weakness when sweets enter the bloodstream too quickly due to intestinal changes

Age of Gastric Bypass Patients, California 1995-2004

Gastric Bypass Age Chart
Source: The Journal of the American Medical Association

Gastric Bypass Patient Criteria

If you are considering gastric bypass surgery, your doctor can help you determine whether or not you are a good candidate for the procedure based on your weight, age, health, previous weight loss attempts, and medical history. Your doctor will review your situation and discuss the various options with you to help you with your decision.

Although every individual is evaluated on a personal basis, the following list provides an overview of general patient criteria for gastric bypass surgery:

  • Body mass index (BMI) is 40 or higher, or 100 pounds overweight for men and 80 pounds overweight for women
  • Body mass index (BMI) is 35 or higher with presence of obesity comorbidities, including type 2 diabetes, severe sleep apnea, heart disease, hypertension (high blood pressure), and high cholesterol
  • History of obesity (at least 5 years)
  • Previous attempts at weight loss have failed, including participation in a medically supervised weight loss program
  • Do not have health conditions that would make surgery an unacceptable risk
  • Emotionally stable and able to pass a psychological evaluation
  • Understand and willing to make the necessary diet and lifestyle changes required by surgery

Results of Gastric Bypass Surgery

Gastric bypass surgery can help you lose a substantial amount of weight in a relatively short amount of time. Weight loss is quite rapid during the first six months following surgery, but gradually slows down as the body adapts to the changes. Weight loss eventually settles and the final weight is reached about 18 to 24 months after surgery.

  • On average, gastric bypass patients can expect to lose about 50% to 60% of the excess weight. Many patients have been able to lose 70% to 80% of the excess weight. Weight loss is typically at 70% after one year, but at 60% excess weight loss after five years, due to weight regain which usually occurs after the initial weight loss.

Although gastric bypass surgery can be very successful in leading to weight loss, long-term weight loss is not a guarantee. The amount of weight loss and long-term results is affected by a person’s age, weight prior to surgery, health, and compliance with dietary and exercise guidelines. Long term weight loss maintenance is possible for patients who continue to follow a healthy diet and exercise behaviors.

Gastric bypass surgery is also very effective at resolving or improving many health conditions associated with obesity, including type 2 diabetes, hypertension, sleep apnea, and arthritis. Many patients are able to reduce their dependency on medications for these health conditions soon after surgery, even before weight loss is finished.

Bariatric Surgeons
The main reasons that patients chose gastric bypass surgery were more overall weight loss, quicker weight loss, and felt it was better for them.