Weight regain after bypass: 44% or 67% of patients, depending on the definition

The operative risk, by procedure

The reference meta-analysis covers 58 studies and more than 3.6 million patients (Robertson, Br J Surg, 2021).

Quoting a single figure of 0.1% loses the most useful information: the spread between procedures is fourteenfold, and it is statistically significant. This level of risk is comparable to a laparoscopic cholecystectomy or a knee replacement.

One factor weighs heavily: in a registry of 180,544 operated patients, 30-day mortality is 0.06% in those without heart failure and 0.74% in those with it, twelve times higher.

What becomes of the weight, and what becomes of the surgery

In the LABS cohort, maximum loss after bypass is 37.4% of starting weight, reached at two years in median. Five years after that low point, median regain is 26.8% of the maximum loss. At seven years, net mean loss is still 28.4% of starting weight.

The gap between 12.2% and 29.9% is not a contradiction: the French database counts declared revisions, SM-BOSS counts conversions in a trial with active follow-up. Both are true, they do not measure the same thing.

Reflux after sleeve, and an epidemic that is not one

Reflux after sleeve is real, substantial and well demonstrated.

The widely quoted figure of 17% Barrett’s oesophagus after sleeve, however, needs requalifying. It comes from a single-centre series of 110 patients with a third lost to follow-up. Randomised trials find 4% at ten years and prospective cohorts 3.6% at seven.

The explanation is published. After a sleeve, a tubularised cardia segment rises above the diaphragm in 26.6% of patients against 0.6% before, and it mimics Barrett’s endoscopically. After histological confirmation, true prevalence is 3.8% after sleeve against 4.1% before, with a p of 0.756: no difference. And 70.8% of biopsies labelled Barrett’s actually showed gastric mucosa.

Alcohol after bypass, the best demonstrated risk

This is the most solidly established risk, because the studies have an internal surgical comparator that neutralises confounding by indication.

In the VA cohort, sleeve compared with a non-surgical weight programme shows no increase at all, with a p of 0.08. The signal is about bypass, and the mechanism is documented: bypass changes alcohol pharmacokinetics. In the Norwegian registry, patients who developed an alcohol-related diagnosis had double the risk of death.

Suicide: robust association, causality not established

The rigorous formulation is this. Relative risk is consistently raised, by a factor of 1.2 to 4.4 depending on the study. Absolute risk remains low. And the study best designed to settle it suggests the excess is carried by psychiatric history, not by the operation.

That study is French: 1,984 patients aged 12 to 25 operated on, followed for three years, with two control groups. Against the general population, surgery is associated with a 3.64-fold risk. But against young people with obesity who were not operated on, surgery is not associated with self-harm: only psychiatric and self-harm history are.

A meta-analysis restricted to matched cohorts gives a hazard ratio of 2.12, and its authors conclude explicitly that absolute risk remains low and does not justify discouraging surgery. The figure of 4.38 that circulates comes from a study whose controls are drawn from the general population, not from people with severe obesity; it is very probably overestimated and should not be quoted alone.

In practice, if this concerns you

Three questions structure the discussion. Do you have reflux before the operation, since that is the strongest argument for bypass over sleeve. Do you have a psychiatric history or an alcohol intake, since that changes the follow-up needed and the choice of procedure. And do you accept lifelong supplementation and blood monitoring.

Noria Health arranges a full metabolic work-up near Brussels within 24 to 48 hours: nutritional and psychological assessment, full blood work, upper endoscopy with reflux assessment, and screening for cardiovascular comorbidities. The report is issued within 24 hours, follow-up is structured at D14, D30 and D90, and surgery is considered only around day 10 if it is needed.

What Noria Health does not do: operate without prior psychological assessment or a nutritional follow-up plan. Persistent vomiting, acute abdominal pain, fever or collapse after bariatric surgery are matters for the emergency services in your country, immediately, not for an appointment.

Further reading

• Surgery or GLP-1: no trial has ever compared them
• Diabetes: 58.8% of surgical remissions had relapsed by ten years
• Barrett: the annual cancer risk is 0.12%

Sources

1. Robertson AGN, Wiggins T, Robertson FP, et al. Perioperative mortality in bariatric surgery, meta-analysis. Br J Surg, 2021;108:892-897. https://pubmed.ncbi.nlm.nih.gov/34297806/
2. King WC, Hinerman AS, Belle SH, Wahed AS, Courcoulas AP. Comparison of the performance of common measures of weight regain after bariatric surgery. JAMA, 2018;320:1560-1569. https://pubmed.ncbi.nlm.nih.gov/30326125/
3. Courcoulas AP, King WC, Belle SH, et al. Seven-year weight trajectories and health outcomes in the LABS study. JAMA Surg, 2018;153:427-434. https://pubmed.ncbi.nlm.nih.gov/29214306/
4. Lazzati A, Bechet S, Jouma S, Paolino L, Jung C. Revision surgery after sleeve gastrectomy, a nationwide study. Surg Obes Relat Dis, 2020;16:1497-1504. https://pubmed.ncbi.nlm.nih.gov/32636173/
5. Kraljevic M, Susstrunk J, Wolnerhanssen BK, et al. Sleeve gastrectomy versus Roux-en-Y gastric bypass at 10 years, SM-BOSS. JAMA Surg, 2025;160:369-377. https://pubmed.ncbi.nlm.nih.gov/39969869/
6. Salminen P, Gronroos S, Helmio M, et al. Sleeve gastrectomy vs gastric bypass at 10 years, SLEEVEPASS. JAMA Surg, 2022;157:656-666. https://pubmed.ncbi.nlm.nih.gov/35731535/
7. Peterli R, Wolnerhanssen BK, Peters T, et al. Effect of laparoscopic sleeve gastrectomy vs gastric bypass on weight loss at 5 years, SM-BOSS. JAMA, 2018;319:255-265. https://pubmed.ncbi.nlm.nih.gov/29340679/
8. Susstrunk J, et al. Oesophageal acid exposure seven years after sleeve gastrectomy and gastric bypass. Surg Obes Relat Dis, 2025;21:1065-1072. https://pubmed.ncbi.nlm.nih.gov/40473520/
9. Wolnerhanssen BK, et al. Reflux and Barrett’s oesophagus after sleeve gastrectomy and gastric bypass. Surg Obes Relat Dis, 2023;19:707-715. https://pubmed.ncbi.nlm.nih.gov/36990881/
10. Genco A, Soricelli E, Casella G, et al. Gastroesophageal reflux disease and Barrett’s esophagus after laparoscopic sleeve gastrectomy. Surg Obes Relat Dis, 2017;13:568-574. https://pubmed.ncbi.nlm.nih.gov/28089434/
11. Johari Y, Wickremasinghe A, Kiswandono P, et al. Mechanisms of esophageal and gastric transit following sleeve gastrectomy. Ann Surg, 2022;276:119-127. https://pubmed.ncbi.nlm.nih.gov/35703462/
12. King WC, Chen JY, Courcoulas AP, et al. Alcohol and other substance use after bariatric surgery. Surg Obes Relat Dis, 2017;13:1392-1402. https://pubmed.ncbi.nlm.nih.gov/28528115/
13. Mahmud N, Panchal S, Abu-Gazala S, et al. Association between bariatric surgery and alcohol use-related hospitalization. JAMA Surg, 2023;158:162-171. https://pubmed.ncbi.nlm.nih.gov/36515960/
14. Strommen M, et al. New alcohol-related diagnoses after bariatric surgery, a national registry study. Int J Obes, 2026;50:1581-1587. https://pubmed.ncbi.nlm.nih.gov/42310387/
15. Konttinen H, Sjoholm K, Jacobson P, et al. Prediction of suicide and non-fatal self-harm after bariatric surgery, SOS. Ann Surg, 2021;274:339-345. https://pubmed.ncbi.nlm.nih.gov/31850987/
16. Goueslard K, Jollant F, Petit JM, Quantin C. Self-harm hospitalisation following bariatric surgery in adolescents and young adults. Clin Nutr, 2022;41:238-245. https://pubmed.ncbi.nlm.nih.gov/34915275/
17. Cui BB, et al. Suicide risk after bariatric surgery, a meta-analysis of matched cohorts. Surg Obes Relat Dis, 2025;21:67-75. https://pubmed.ncbi.nlm.nih.gov/39516067/

See also: all our articles on bariatric and metabolic surgery.

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