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Gastric Bypass Surgery

Gastric bypass surgery, also called the Roux-en-Y gastric bypass procedure, is the most common form of weight loss surgery performed in the United States today.

What is Gastric Bypass Surgery?


Also known as stomach bypass surgery or bariatric bypass surgery, this procedure creates a small pouch that bypasses the stomach and attaches to the intestine. A gastric bypass operation is irreversible, in most cases.


There are two types of gastric bypass surgery performed at UPMC. Your bariatric surgeon will perform gastric bypass surgery either:

  • Laparoscopically, making several small 1/4- to 1/2-inch abdominal incisions.
  • Traditionally as an "open" procedure, making one 10- to 12-inch abdominal incision.

Surgery time is approximately 1.5 hours, and the hospital stay is two to three days. Recovery time is about two weeks.

How you lose weight

Gastric Bypass Surgery restricts the amount of food you can eat and reduces the number of calories your body will absorb. Weight loss is rapid. Expect to lose 60 to 80 percent of excess body weight within 12 to 18 months after surgery.

Gastric Bypass Weight Loss Surgery: What to Expect

Here's what to expect if you're considering a gastric (stomach) bypass surgery procedure.

During gastric bypass surgery

After you receive general anesthesia, your bariatric surgeon will:

  • Assess the abdomen and then use surgical staples to create a small pouch at the top of your stomach.
    • This pouch — which over time can hold about one cup of food — will be your new, smaller stomach.
    • A normal stomach can hold more than four to six cups of food.
  • Cut the small intestine and attach it to the new pouch.
    • With the intestinal bypass, food will now move from the new stomach pouch to the middle section of the small intestine.
    • It will bypass the lower stomach and the upper section of the small intestine.
  • Attach the upper section of the small intestine to the middle section of the small intestine.
    • This will allow digestive fluids, that the lower stomach makes, move down the upper section of the small intestine and into the middle section.
  • Close the incisions with staples or stitches.

Why Is Gastric Bypass Surgery Performed?

Those who are severely overweight and cannot lose weight through diet and exercise may turn to gastric bypass surgery.

Undergoing gastric bypass surgery is a serious commitment to a healthier lifestyle — patients must:

  • Greatly change their lifestyle.
  • Learn to control portion sizes.
  • Exercise regularly.

Doctors may perform this procedure on patients with a high Body Mass Index as well as obesity-related health conditions.

After gastric bypass bariatric surgery

  • You can expect to stay in the hospital for two to three days.
  • The morning after your gastric bypass surgery, you will:
    • Start a clear liquid diet for at least two weeks. It's very important that you drink at least 64 ounces of fluid every day to avoid becoming dehydrated.
    • Begin to go for walks around your room and in the halls.
  • Immediately before discharge, your bariatric surgery team will give you instructions on how to care for yourself at home, including:
    • Incision and drainage care
    • Pain control
    • Vitamin supplements to get adequate amounts of vitamin B12, iron, and calcium

Benefits of Gastric Bypass Surgery

  • Long-term weight loss: Many people who undergo gastric bypass surgery experience rapid weight loss following the procedure and continue to lose weight months and years later.
  • Reducing or curing a variety of obesity-related illnesses, including diabetes, high blood pressure, and sleep apnea.
  • Improved quality of life and mood: Many people who undergo gastric bypass surgery report a decrease in depression and anxiety, as well as improved self-esteem, sexual function, and social interactions.

Find out more about the benefits of weight-loss surgery.

Gastric Bypass Surgery Requirements

People who qualify for gastric bypass surgery include:

  • Those with a Body Mass Index greater than or equal to 40, or who are more than 100 pounds overweight.
  • Those with a Body Mass Index greater than or equal to 35 who have at least two obesity-related conditions. This could include: Type 2 Diabetes, hypertension, or heart disease, among others.
  • Those who cannot achieve a healthy weight with diet and exercise.

Learn how to calculate your own Body Mass Index.

Dumping Syndrome and Other Gastric Bypass Surgery Risks

Dumping syndrome is a potential risk of gastric bypass surgery. It occurs when large volumes of food in the stomach move too quickly through the small intestine, frequently after eating sweet or high-fat foods.

Dumping syndrome can cause:

  • Nausea
  • Vomiting
  • Cramps
  • Diarrhea
  • Sweating
  • Dizziness
  • Weakness

Other gastric bypass surgery risks and complications include:

  • Perforation of stomach or intestines
  • Leakage of surgical connection between the stomach and the intestine
  • Internal bleeding or profuse bleeding of the surgical wound
  • Gastric pouch/anastomotic obstruction or bowel obstruction

Your bariatric surgeon will review all potential gastric bypass surgery risks, complications, and other weight loss surgery options with you prior to your procedure. If you have any questions about gastric bypass surgery, we encourage you to ask your surgeon.

Learn more about what to expect after gastric bypass surgery.