At a glance
- What the surgery does
- Makes the stomach much smaller (sleeve) or creates a small pouch connected to the intestine (bypass), changing appetite and metabolism.
- Why people consider it
- A BMI of 35 or more, or 30 or more with conditions like type 2 diabetes, especially when other approaches haven't worked.[1]
- The main choices
- Sleeve or bypass, and how surgery fits with GLP-1 medicines. Bypass led to more weight loss and less reflux damage than sleeve at 10 years in one trial.[5]
- What recovery involves
- One or two nights in hospital, weeks of liquid then soft foods, and lifelong vitamins, follow-up and blood tests.
- What to ask your surgeon
- Which procedure suits you and why, how medication fits in, and what support the program provides long-term.
The short version
- Current guidelines recommend surgery for a BMI of 35 or more, and say it can be considered from a BMI of 30 with metabolic disease such as type 2 diabetes.[1]
- In a Swedish study following thousands of people for more than 20 years, surgery patients lived about 3 years longer on average than similar people who had usual care.[3]
- Gastric bypass led to somewhat more weight loss than the sleeve at 10 years in a Finnish trial, and the sleeve caused more reflux-related inflammation of the esophagus.[5]
- For type 2 diabetes, surgery plus medical therapy controlled blood sugar better than intensive medical therapy alone at five years.[4]
- Newer medicines such as semaglutide and tirzepatide produce large weight loss in trials, though typically less than surgery, and are generally meant to be taken long-term.[11][12]
Who qualifies
In 2022 the two main surgical societies updated decades-old criteria. They recommend metabolic and bariatric surgery for adults with a BMI of 35 or higher, whether or not they have obesity-related conditions, and say it should be considered for adults with a BMI of 30 to 34.9 who have metabolic disease. Lower thresholds apply to people of Asian descent.[1]
Insurance rules often lag behind. Some plans still use older criteria and ask for documented weight-loss attempts and evaluations first. Some insurers also require surgery at a center that meets ASMBS quality standards.[15] Medicare covers some procedures for people who meet its criteria.[14]
A good program includes a surgeon, dietitian, psychologist and medical team, and lifelong follow-up. Ask whether the center is accredited.[13]
What surgery does long-term
Weight and survival
The Swedish Obese Subjects study compared about 2,000 people who had surgery with about 2,000 similar people who received usual care. With a median follow-up of more than 20 years, the surgery group had a lower risk of death from any cause, heart disease and cancer, and lived about 3 years longer on average, though still about 5.5 years less than the general population.[3] An earlier report from the same study also found lower death rates after surgery.[2]
Diabetes
In the US STAMPEDE trial of 150 people with type 2 diabetes, 29% after gastric bypass and 23% after sleeve gastrectomy reached a near-normal blood sugar level (HbA1c 6% or less) at five years, compared with 5% on intensive medical therapy alone. Surgery groups also lost far more weight and used less insulin.[4] An Italian trial with 10 years of follow-up found many more surgery patients than medical patients were still in diabetes remission.[9]
A long-term US study of gastric bypass found most of the weight loss was maintained at 12 years.[8]
Sleeve or bypass?
| Operation | What it does | What the evidence says |
|---|---|---|
| Sleeve gastrectomy | Removes about three quarters of the stomach, leaving a narrow tube. Nothing is rerouted. | Now the most common procedure. In the Finnish SLEEVEPASS trial, excess weight loss at 10 years was about 44% versus 51% for bypass. Inflammation of the esophagus from reflux was found in 31% after sleeve versus 7% after bypass, though Barrett's esophagus was 4% after both.[5] |
| Roux-en-Y gastric bypass | Creates a small stomach pouch and connects it directly to a lower part of the small intestine. | Somewhat more weight loss than sleeve at 10 years, and better remission of high blood pressure.[5] Often preferred for people with significant reflux. A Swiss trial found no significant difference in weight loss between the two at five years.[6] More long-term risk of vitamin and mineral deficiencies and certain bowel complications. |
| Other procedures | Duodenal switch, one-anastomosis bypass, revisional surgery, and endoscopic sleeve procedures. | Used in specific situations. Ask why one would or wouldn't suit you.[1] |
Reoperation rates over 10 years were similar after sleeve and bypass in SLEEVEPASS, around 16% to 19%.[5]
Surgery or the new medications?
GLP-1-based medicines have changed obesity treatment. In the STEP 1 trial, weekly semaglutide led to about 15% average weight loss at 68 weeks versus about 2% with placebo.[11] In SURMOUNT-1, weekly tirzepatide led to average losses of about 15% to 21% at 72 weeks, depending on dose, versus about 3% with placebo.[12]
The research in detail
Surgery generally produces larger and more durable weight loss, with a single operation. Medicines avoid surgical risk but usually need to be taken long-term, can be expensive or hard to get covered, and have side effects such as nausea. There are no large head-to-head randomized trials comparing modern surgery with these drugs yet.
Many people now use both: medication before surgery, or after surgery if weight returns. Ask your team how they'd combine them for you.
Before and on surgery day
Most programs include nutrition counseling, a psychological evaluation, and sometimes a short liver-shrinking diet before surgery. Stopping smoking is strongly encouraged.
Both sleeve and bypass are almost always done laparoscopically or robotically, and usually take one to three hours. Most people stay in hospital one or two nights. In a large US multicenter study, 0.3% of patients died within 30 days of surgery and 4.3% had a major complication.[10]
Recovery and life after surgery
- Weeks 1 to 2Clear liquids, then full liquids. Small sips all day to stay hydrated. Walking from the first day.
- Weeks 2 to 6Pureed then soft foods, very small portions, protein first. Most people return to desk work within a few weeks.
- Months 2 to 18Regular textures, small meals. Most weight loss happens in this period. Regular follow-up visits and blood tests.
- For lifeDaily vitamins and minerals, yearly blood tests, protein-focused eating and regular activity.[13]
Alcohol
Alcohol is absorbed faster after bariatric surgery, especially bypass. In a large US study, symptoms of alcohol use disorder became more common in the second year after gastric bypass.[7] Many programs advise avoiding alcohol for the first year and being cautious after that.
Pregnancy
Fertility often improves with weight loss. Most programs advise waiting 12 to 18 months after surgery before trying to conceive, and using reliable contraception until then.
Risks and complications
- Short-term: leaks from staple lines, bleeding, blood clots and infection. Serious complications are uncommon at experienced centers.[10]
- Reflux, especially after sleeve gastrectomy.[5]
- Nutrient deficiencies (iron, B12, vitamin D, calcium and others), especially after bypass, which is why lifelong supplements and blood tests matter.[13]
- Dumping syndrome after bypass: cramping, sweating and diarrhea after sugary food.
- Gallstones during rapid weight loss.
- Weight regain in some people over the years.[5][8]
- Alcohol problems in a minority after bypass.[7]
- Further surgery for complications or revision.[5]
Questions to ask your surgeon
- Which procedure do you recommend for me, and why?
Why we ask: Sleeve and bypass differ in weight loss, reflux and long-term nutrition. Your health history should drive the choice. Sleeve or bypass?
- Given my reflux and other conditions, how might sleeve or bypass affect me?
Why we ask: Esophagus inflammation from reflux was far more common after sleeve than bypass at 10 years in a Finnish trial. Sleeve or bypass?
- Should I try medication first, or combine it with surgery?
Why we ask: GLP-1 medicines produce substantial weight loss and many people now use them before or after surgery. Surgery or the new medications?
- Is your center accredited, and how many of these do you do each year?
Why we ask: Experienced, accredited programs offer the team and follow-up that long-term success depends on. Who qualifies
- What does your program include before and after surgery, and for how long?
Why we ask: Nutrition, psychology and medical follow-up matter for life, not just around surgery. Recovery and life after surgery
- What will my insurance require before approving surgery?
Why we ask: Some plans still use older criteria and ask for documented weight-loss attempts and evaluations, which can take months. Who qualifies
- What vitamins and blood tests will I need long-term?
Why we ask: Deficiencies are common without lifelong supplements, especially after bypass. Risks and complications
- What happens if I regain weight later?
Why we ask: Some regain is common. Knowing the options, from medication to revision surgery, helps you plan. Surgery or the new medications?
Print this page or save it to your phone, and write down the answers during your visit.
Understanding your surgical technology options
The companies that make the implants and devices used in this surgery, compared side by side with FDA records and sources, plus recent research and FDA news explained for patients.
Recovery supplies
We list recovery supplies at every budget, from gel ice wraps to cold therapy machines, with what to look for in each.
- Measuring and portioning
- Hydration
- Vitamins and protein
- Walking
Sources
- Eisenberg D, et al. 2022 American Society for Metabolic and Bariatric Surgery (ASMBS) and International Federation for the Surgery of Obesity and Metabolic Disorders (IFSO): indications for metabolic and bariatric surgery. Surg Obes Relat Dis. 2022;18:1345-56. https://doi.org/10.1016/j.soard.2022.08.013
- Sjöström L, et al. Effects of bariatric surgery on mortality in Swedish obese subjects. N Engl J Med. 2007;357:741-52. https://pubmed.ncbi.nlm.nih.gov/17715408/
- Carlsson LMS, et al. Life expectancy after bariatric surgery in the Swedish Obese Subjects study. N Engl J Med. 2020;383:1535-43. https://doi.org/10.1056/NEJMoa2002449
- Schauer PR, et al. Bariatric surgery versus intensive medical therapy for diabetes: 5-year outcomes. N Engl J Med. 2017;376:641-51. https://doi.org/10.1056/NEJMoa1600869
- Salminen P, et al. Effect of laparoscopic sleeve gastrectomy vs Roux-en-Y gastric bypass on weight loss, comorbidities, and reflux at 10 years in adult patients with obesity: the SLEEVEPASS randomized clinical trial. JAMA Surg. 2022;157:656-66. https://doi.org/10.1001/jamasurg.2022.2229
- Peterli R, et al. Effect of laparoscopic sleeve gastrectomy vs laparoscopic Roux-en-Y gastric bypass on weight loss in patients with morbid obesity: the SM-BOSS randomized clinical trial. JAMA. 2018;319:255-65. https://pubmed.ncbi.nlm.nih.gov/29340679/
- King WC, et al. Prevalence of alcohol use disorders before and after bariatric surgery. JAMA. 2012;307:2516-25. https://pubmed.ncbi.nlm.nih.gov/22710289/
- Adams TD, et al. Weight and metabolic outcomes 12 years after gastric bypass. N Engl J Med. 2017;377:1143-55. https://pubmed.ncbi.nlm.nih.gov/28930514/
- Mingrone G, et al. Metabolic surgery versus conventional medical therapy in patients with type 2 diabetes: 10-year follow-up of an open-label, single-centre, randomised controlled trial. Lancet. 2021;397:293-304. https://pubmed.ncbi.nlm.nih.gov/33485454/
- Longitudinal Assessment of Bariatric Surgery (LABS) Consortium. Perioperative safety in the longitudinal assessment of bariatric surgery. N Engl J Med. 2009;361:445-54. https://pubmed.ncbi.nlm.nih.gov/19641201/
- Wilding JPH, et al. Once-weekly semaglutide in adults with overweight or obesity. N Engl J Med. 2021;384:989-1002. https://pubmed.ncbi.nlm.nih.gov/33567185/
- Jastreboff AM, et al. Tirzepatide once weekly for the treatment of obesity. N Engl J Med. 2022;387:205-16. https://pubmed.ncbi.nlm.nih.gov/35658024/
- National Institute of Diabetes and Digestive and Kidney Diseases. Bariatric surgery. https://www.niddk.nih.gov/health-information/weight-management/bariatric-surgery
- Medicare.gov. Bariatric surgery coverage. https://www.medicare.gov/coverage/bariatric-surgery
- American Society for Metabolic and Bariatric Surgery. Is metabolic and bariatric surgery right for you? https://asmbs.org/patients/is-metabolic-and-bariatric-surgery-right-for-you/
Spot an error? Tell us and we'll check it and fix it.