Gastric Sleeve Surgery: What It Is and What to Expect

Oct 12, 2026

Gastric sleeve surgery, also called sleeve gastrectomy or vertical sleeve gastrectomy (VSG), shrinks the stomach so you feel full sooner. It is the most common weight-loss operation in the United States.

Know the warning signs after weight-loss surgery. UCSF Health tells bariatric patients to contact their surgeon right away for a fever of 101.5°F or higher; a wound that is red, swollen or leaking pus; nausea or vomiting that lasts more than 12 hours; pain or swelling in a leg; or pain that pain medicine doesn’t help. MedlinePlus says to call 911 for trouble breathing, chest pain lasting two minutes or more, severe belly pain, vomiting blood or fainting.

In the video above, LoneStar Bariatrics, the North Texas practice of bariatric surgeon Dr. Chad Carlton, shows how gastric sleeve surgery is performed. The information below comes from the medical sources listed at the end of this article.

What is a gastric sleeve?

The surgeon removes about 80% of the stomach. What’s left is a narrow, banana-shaped tube. The intestines aren’t changed.

With a smaller stomach, you fill up on less food. The removed part also makes most of ghrelin, a hunger hormone, so taking it out can lower appetite. A sleeve can’t be reversed.

Who is it for?

Guidelines updated in 2022 by the American Society for Metabolic and Bariatric Surgery (ASMBS) recommend weight-loss surgery for adults with:

  • a body mass index (BMI) of 35 or higher, with or without other health problems
  • type 2 diabetes and a BMI of 30 or higher

ASMBS says surgery should also be considered at a BMI of 30 to 34.9 when other methods haven’t brought lasting results. For people of Asian descent, weight-related disease may show up at a lower BMI.

Some hospital guides still use older cutoffs: a BMI of 40 or higher, or 35 or higher with a condition such as sleep apnea or type 2 diabetes. Teens may qualify after an evaluation by a pediatric team.

Preparing takes time: an education program, nutrition counseling, often a mental health evaluation, and exams and tests. You’ll need to quit smoking. Some insurance plans first require three to six months in a supervised weight-loss program.

How the surgery is done

You’re asleep under general anesthesia. Most sleeves are done with laparoscopic or robotic surgery through several small cuts in the belly. Guided by a camera, the surgeon uses a stapler to divide the stomach and removes the larger, outer part. The surgeon may then check the sleeve for leaks. If small cuts aren’t safe, the surgeon may switch to one larger, open cut.

Surgery usually takes one to two hours, and most people go home in a day or two.

Benefits

  • Weight loss. Cleveland Clinic reports an average loss of 25% to 30% of body weight in the first one to two years. Results vary and depend on habits.
  • Better health. Type 2 diabetes, high blood pressure, sleep apnea, high cholesterol, fatty liver disease and joint pain can improve, and sometimes go away.
  • A simpler operation. It’s quicker and simpler than a bypass and may be safer for some people with heart, lung or liver problems.
  • Fewer nutrition problems than a bypass, because the intestines aren’t rerouted.

Risks and side effects

Any major surgery can cause bleeding, infection, blood clots or problems from anesthesia. ASMBS puts the risk of major complications from bariatric surgery at about 4%, and the risk of death at about 0.1%, varying by procedure.

Other possible problems include:

  • a leak along the staple line
  • narrowing (stricture) of the sleeve, causing nausea, vomiting and trouble eating
  • new or worse heartburn and acid reflux
  • hiatal hernia, where the stomach bulges up against the diaphragm
  • low vitamins and minerals, such as iron
  • gallstones, which can form with fast weight loss
  • loose skin after major weight loss

The National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK) reports that about one in three weight-loss surgery patients needs another procedure or hospital stay within five years, less often after a sleeve than a bypass.

Recovery and life after surgery

You’ll start walking within hours to a day after surgery. Plan on about a month before you feel like yourself or work at full speed. Avoid hard exercise and heavy lifting until your surgeon says it’s OK.

Your diet moves in stages over several weeks: liquids, pureed foods, soft foods, then regular food. Eat tiny meals slowly and chew well. Rushing ahead can cause pain and vomiting.

Over the long term:

  • Vitamins for life. Expect to take vitamins and minerals daily, usually a multivitamin plus calcium and vitamin D. Some people also need iron or vitamin B12. Skipping them can lead to anemia, weak bones and other serious problems.
  • Checkups. In the first year, you’ll see your team and have blood tests every few months. After that, plan on a yearly visit for life.
  • Healthy eating and exercise. These still matter, because the sleeve can stretch and weight can return.
  • Alcohol and nicotine. Alcohol reaches your blood faster after surgery. Nicotine slows healing.
  • Pregnancy. ASMBS advises waiting 12 to 18 months. Fertility often improves, so plan birth control early.

If weight returns, options include lifestyle help, weight-loss medicine or another operation.

Sleeve or bypass?

In a Roux-en-Y gastric bypass, the surgeon makes an egg-sized stomach pouch and connects it to the small intestine. Food skips most of the stomach and the first part of the intestine.

  • Weight loss: A bypass tends to bring somewhat more weight loss, but more complications in the first month.
  • Reflux: A sleeve can cause or worsen reflux, while a bypass often improves it. If you already have moderate or severe reflux, ask whether a bypass would suit you better.
  • Nutrition and complexity: A bypass is more complex and causes more vitamin and mineral shortages. It adds risks such as ulcers and small-bowel blockage.
  • Later options: A sleeve can later be converted to a bypass or another operation.

Questions to ask your surgeon

  • Which operation do you recommend for me, and why?
  • Am I a good candidate?
  • What must I do before surgery, and how long will it take?
  • Is your program accredited, and how many sleeves do you perform?
  • I have heartburn. Is a sleeve still a good choice?
  • Which vitamins will I need, and how often will I have checkups?

Dr. Carlton is a bariatric surgeon in the Dallas–Fort Worth area. See Dr. Carlton’s Best Docs Network profile for more about the practice.

Sources

This article is for general information only and is not medical advice. Talk with a qualified health professional about your own situation. If you think you may have a medical emergency, call 911.

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