WebMD Logo Icon
WebMD Connect to Care helps you find services to manage your health. When you purchase any of these services, WebMD may receive a fee. WebMD does not endorse any product, service or treatment referred to on this page. X

What is Gastric Bypass Surgery?

By  Zawn Villines
Gastric bypass can help you lose weight by reducing hunger and shrinking the size of your stomach. Here's what you need to know about this weight loss surgery.

If you've struggled to lose weight, have serious weight-related health problems, and feel like nothing works, gastric bypass surgery could improve your health and your life.

This procedure can help you rapidly lose weight and keep it off. A 2016 study of patients who underwent the procedure found that they also reduce their risk of dying within 10 years of surgery by 48 percent. So what is gastric bypass, and is it right for you? Here's what you need to know.

What is Gastric Bypass Surgery?

Gastric bypass helps you lose weight in three ways:

  1. It shrinks the size of your stomach, reducing the size of meals you can eat and potentially making you feel less hungry.
  2. It changes the way your digestive system works, reducing the amount of food you can absorb.
  3. It reroutes food through a smaller portion of the digestive system. This means changes the food-related hormones the body produces, causing a person to feel full and satisfied faster and hungry less frequently.

To accomplish this, a surgeon reduces the stomach to about 30 milliliters by pinching the top of the stomach off from the bottom. Then, the surgeon divides the top portion of the small intestine, removing a portion. From there, they connect the small intestine to the newly created stomach.

Finally, the surgeon connects a portion of the newly divided small intestine to a lower portion of the small intestine. This enables digestive enzymes and stomach acids to mix with food, but reduces the amount of food the body can absorb.

Potential Drawbacks of Gastric Bypass

All surgeries carry some risks, and weight loss surgery is no exception. During and immediately after surgery, a person may experience anesthesia complications, excessive bleeding, infections, allergic reactions to surgical materials, and similar surgical complications. However, gastric bypass surgery is safe for most patients, with a 30-day death rate of 0.13 percent—or about 1 in 1,000. This is a lower death rate than many other surgeries, such as gallbladder removal.

After surgery, there are several potential long-term drawbacks of the procedure, including:

  • lower alcohol tolerance
  • small weight gain after initial weight loss, with about half of patients regaining 5 percent of their initial weight loss within 2 years
  • a risk of vitamin and mineral deficiencies, especially if you don't follow a doctor's supplementation recommendations
  • strict dietary guidelines, especially in the weeks and months immediately following surgery

Benefits of Gastric Bypass

People who undergo gastric bypass surgery typically lose significant weight. More than 85 percent of patients lose at least 50 percent of their extra weight, and maintain this loss. This offers numerous benefits, including:

  • a lower risk of weight-related health problems such as cardiovascular disease and type 2 diabetes
  • a decreased risk of dying
  • less embarrassment about weight
  • in some people, mental health improvements such as less depression and a better body image
  • less weight-related frustration, and fewer difficulties losing weight or avoiding overeating
  • a longer, healther life