A gastric bypass, or bariatric surgery, is a procedure that aims to help manage obesity.

About 24 million people in the United States have severe obesity, meaning that they have a body mass index (BMI) of 40 or over.

Recent statistics from the Centers for Disease Control and Prevention (CDC) show that the obesity rate in adults in the U.S. was 42.4% in 2017–2018, a significant increase from the 1999–2000 rate of 30.5%.

Obesity can increase the risk of diabetes, arthritis, high blood pressure, heart disease, and other health conditions. Healthcare professionals recommend losing weight to promote overall health.

A gastric bypass is one way to treat obesity and help a person lose weight. Keep reading to learn about the procedure and its effects.

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A doctor may recommend a gastric bypass to a person who is unable to lose weight through lifestyle changes.

Although diet and exercise are usually the first recommendations for losing weight, these do not work for everyone.

In cases where lifestyle changes are ineffective, a doctor may recommend surgery. A gastric bypass, or bariatric surgery, is a type of procedure that can be a sustainable, long-term option for weight loss.

Generally, these procedures work in one of three different ways:

  • Restrictive: A surgeon decreases the size of the stomach.
  • Malabsorptive: A surgeon reduces the amount of the small intestine that food can pass through.
  • Mixed: These procedures limit the intake of food and produce malabsorption.

Laparoscopic adjustable gastric banding (LAGB) is one of the types of restrictive weight loss surgeries. People sometimes refer to it as a gastric sleeve.

It involves a surgeon inserting an instrument called a laparoscope through small incisions in the upper abdomen and putting an adjustable band around the top part of the stomach to create a small pouch. The result is that the person feels fuller despite eating less.

LAGB is the least invasive gastric procedure. A doctor can adjust the band when necessary to allow an increased or reduced food intake.

Vertical sleeve gastrectomy (VSG) is a procedure more commonly known as “stomach stapling.”

During the surgery, a surgeon will permanently remove part of the stomach, limiting the amount of food that a person can eat.

They will also remove most and perhaps all of the ghrelin-producing cells of the mucous membrane layer of the stomach.

Ghrelin is a hunger hormone, so reducing its production means that a person’s appetite will decrease dramatically.

The surgeon will join the remaining parts of the stomach together using surgical staples.

In a Roux-en-Y gastric bypass (RYGB), a surgeon reduces the size of the stomach to approximately that of a golf ball.

They do this by stapling off a small pouch of the stomach away from the rest before attaching this section of the stomach to part of the small intestine called the Roux limb.

Food will pass straight from the small pouch to the lower part of the small intestine. This procedure is a malabsorptive one, as the less time food spends in the small intestine, the less the body absorbs.

The recovery time will depend on the type of procedure. In general, the more invasive the procedure, the longer the recovery time.

A person’s recovery can also depend on whether there were any complications during the surgery.

Dietary changes are necessary after a gastric bypass to ensure that complications do not occur. People should always follow doctors’ advice on what to eat.

The diet will change slowly in stages. An aftercare diet plan may involve the following stages:

  • Clear liquids: For the first day, it is only possible to have clear liquids, such as water. The aim is to ensure that the person remains hydrated but avoids anything that could irritate the stomach.
  • Liquids: After the initial day, a person may be able to introduce other liquids, such as protein shakes, slowly to ensure that they are getting enough nutrients. This stage could last 14 days.
  • Soft food: People can eat pureed food, and protein shakes become supplemental rather than the only source of protein.
  • Regular food: About 7 weeks after surgery, people can eat regular foods. It is still vital to avoid certain ingredients, however, such as added sugars and caffeine.

The dietary recommendations will vary depending on a person’s medical history and other health conditions.

Each individual will receive personalized advice from a doctor or registered dietitian to ensure that they have an appropriate diet.

As with all surgeries, a gastric bypass has risks and potential complications, such as the risk of infection.

However, the common misconception that the chance of dying from metabolic and bariatric surgery is higher than the chance of dying from obesity is false.

Information from the American Society for Metabolic and Bariatric Surgery (ASMBS) shows that the risk of death within the 30 days following bariatric surgery averages 0.13%, or approximately 1 out of 1,000 patients.

This risk is substantially less than it is following most other operations, the ASMBS say.

Other complications

Other possible complications of bariatric surgery include:

  • Dumping syndrome: This group of symptoms occurs when food and liquids enter the small intestine rapidly and in larger amounts than normal. People may experience sweating, dizziness, palpitations, abdominal pain, nausea, vomiting, or diarrhea.
  • Leaks: Leaks can occur due to the surgery, but the surgeon will usually check for them before finishing the procedure. It is vital to have regular checkups to ensure that leaks have not occurred later on.
  • Constipation: Constipation can arise due to a person not drinking enough fluids.
  • Skin folds: These can occur due to weight loss of any kind, not just as a result of gastric bypass surgery.
  • Vitamin deficiencies: A drastic reduction in the amount of food that a person eats can cause a lack of appropriate vitamins and minerals in the diet. A dietitian can offer advice on which foods to eat.
  • Not losing weight: If a person receives gastric bypass surgery but does not substantially change their diet, they may not lose weight. In the case of LAGB, the band can widen over time. As a result, a person will be able to eat more, potentially leading to weight gain.

Gastric bypass surgery is by no means an “easy fix,” as it involves making a lot of dietary changes to allow weight loss to occur. However, it can be a significant step toward a moderate body weight for many people.

The benefits of gastric bypass surgery usually outweigh the risks. Weight loss support groups, especially those specifically for people who have had surgery, can help a person stick to their postsurgery routine and provide vital emotional support.