Dr. Solon Gonçalves Souza Menezes
Professor of Surgery — FAMED UFU · Robotic Surgery Certification (Intuitive / Albert Einstein Hospital) · Practices at Hospital UMC and Hospital Mater Dei Santa Genoveva, Uberlândia, Brazil · +55 (34) 99341-0915
Obesity is a chronic disease, and bariatric and metabolic surgery is today the treatment with the greatest sustained weight loss and the greatest effect on type 2 diabetes, hypertension, sleep apnea and other associated diseases. As the Brazilian Federal Council of Medicine (CFM) rule states (Resolution CFM No. 2,429/2025), surgery “does not determine a cure” but is “an essential part of a multidisciplinary treatment” — a sentence that sums up well what the patient should expect: a powerful tool that requires lifelong follow-up and does not replace lifestyle change.
In Brazil, the indication follows objective criteria defined by the CFM in Resolution 2,429/2025: body mass index (BMI) of 40 kg/m² or more, regardless of other diseases; BMI between 35 and 40 with at least one disease worsened by obesity; and BMI between 30 and 35 in the presence of specific conditions, such as type 2 diabetes, severe sleep apnea, fatty liver disease with fibrosis, reflux with a surgical indication or severe osteoarthritis. The rule requires failure of clinical treatment, recognized by the surgeon and the multidisciplinary team, and sets no maximum age. The joint statement of the American and international bariatric surgery societies (ASMBS/IFSO 2022) points the same way: surgery recommended from BMI 35 regardless of comorbidities and, in type 2 diabetes, from BMI 30.
Two operations account for about 90% of procedures worldwide and are the ones “highly recommended” by the CFM as primary surgery. In sleeve gastrectomy, about 80% of the stomach is removed, leaving a narrow tube: the patient eats less and the production of appetite hormones decreases. In Roux-en-Y gastric bypass, a small gastric pouch is created and connected directly to a loop of small intestine; the rest of the stomach and the duodenum stay in place but out of the path of food. The bypass has a stronger metabolic effect and is the preferred choice when there is significant gastroesophageal reflux; the sleeve is technically simpler, preserves endoscopic access to the stomach and does not change absorption, but can worsen reflux. The adjustable gastric band and the Scopinaro procedure are not authorized by the CFM.
Dr. Solon Gonçalves performs bypass and sleeve by laparoscopy and by robotic surgery, at Hospital UMC and Hospital Mater Dei Santa Genoveva in Uberlândia, Brazil — large hospitals with intensive care units, as the rule requires. The mandatory multidisciplinary assessment (endocrinology, cardiology, psychiatry, nutrology, nutrition and psychology) is carried out with partner professionals, to whom the patient is referred before and after the operation. On robotics, the transparency is the same as on the other pages of this site: the 2024 meta-analyses found no clinical advantage of robotics over laparoscopy in sleeve or bypass — complications, leaks, mortality and weight loss were equivalent, with longer time and higher cost for the robot. The robotic platform is an option in selected cases, such as very high BMI or revisional surgery, decided with the patient.
Book a consultationIndication criteria under the CFM rule (Resolution 2,429/2025).
The criteria below are those of the current rule of the Brazilian Federal Council of Medicine, amended by Resolution 2,470/2026 as to the composition of the team. The final indication is always individual, made together with the multidisciplinary team.
BMI of 40 or more
Class 3 obesity: the indication does not depend on the presence of other diseases. Above 60 kg/m², the rule requires an assessment of the hospital's structural capacity.
BMI between 35 and 40
With at least one disease worsened by obesity that improves with weight loss — type 2 diabetes, hypertension, sleep apnea, dyslipidemia, joint disease, among others.
BMI between 30 and 35
Only in the presence of the conditions listed by the CFM: type 2 diabetes; severe cardiovascular disease with target-organ damage; early chronic kidney disease in diabetics; severe sleep apnea; fatty liver disease with fibrosis; conditions with an indication for transplant; reflux with a surgical indication; severe osteoarthritis.
Contraindications
Obesity controllable clinically; untreated illicit drug use; pregnancy; and inability to adhere to multidisciplinary follow-up and lifestyle changes. Adolescents from the age of 16 follow adult criteria; between 14 and 16, only exceptional cases.
What the 5- and 10-year clinical trials show.
Two European randomized trials — SM-BOSS (Switzerland, 217 patients) and SLEEVEPASS (Finland, 240 patients) — compared the two techniques with 5 and 10 years of follow-up. A meta-analysis of 33 trials (2,475 patients) pooled the others. The numbers below are group averages and do not predict an individual's result.
| Outcome | Sleeve gastrectomy | Roux-en-Y gastric bypass |
|---|---|---|
| Excess weight loss at 5 years (SLEEVEPASS) | 49% | 57% |
| Excess weight loss at 10 years (SLEEVEPASS) | 43.5% | 50.7% |
| Type 2 diabetes remission at 10 years | 26% | 33% (difference not significant) |
| Hypertension remission at 10 years | 8% | 24% |
| Reflux at 5 years (SM-BOSS) | Worsened in 31.8%; remission in 25% | Worsened in 6.3%; remission in 60.4% |
| Esophagitis at 10 years (SLEEVEPASS) | 31% | 7% |
| Reoperations or interventions at 5 years (SM-BOSS) | 15.8% | 22.1% |
| Nutrient absorption | Preserved; supplementation still necessary | Reduced; lifelong supplementation mandatory |
| Reversibility | Irreversible (part of the stomach is removed) | Technically reversible in exceptional situations |
On a phone, drag the table sideways to see all the columns.
What to expect before and after surgery.
Preoperative preparation
Preparation starts months before surgery, with the multidisciplinary team: endocrine and cardiology assessment, psychiatric and psychological assessment, nutritional guidance and tests — upper endoscopy, abdominal ultrasound (gallstones are frequent and can be removed in the same operation), complete blood tests including vitamins, and an anesthetic assessment. A diet for a few weeks before the operation reduces the size of the liver and makes surgery easier. Stopping smoking is mandatory. Patients using GLP-1 medications (semaglutide, tirzepatide) must inform the team, because of their effect on gastric emptying and anesthesia.
Recovery and postoperative care
The hospital stay is usually 2 to 3 days. The diet progresses from liquid to soft and solid over about a month, with follow-up by the nutrition team. Walking from the first day is part of thrombosis prevention. Work without effort is usually resumed in 2 to 3 weeks and intense exercise after 4 to 6 weeks. Follow-up is lifelong: consultations with the team, blood tests at least yearly and replacement of vitamins and minerals — the American (ASMBS 2017) and British (BOMSS 2020) guidelines advise nutritional monitoring for life, and the CFM requires replacement of vitamins and minerals when necessary. Weight loss is greatest in the first year and stabilizes between the second and third.
The real risks, with the published numbers.
The perioperative mortality of bariatric surgery is very low — between 0.03% and 0.2%, according to ASMBS/IFSO 2022 —, but complications exist, some of them serious, and the CFM rule requires that the patient be informed of all of them, including the possibility of weight regain and revisional surgery.
- Staple-line or anastomotic leak — the most feared complication. In the sleeve, large North American registries show about 0.3% to 0.4% at 30 days; a review of 148 studies published between 2012 and 2016 found 1.5%, varying with technique and the experience of the service. In the bypass, it is a rare but serious complication. Treatment may require further surgery, endoscopy and a prolonged hospital stay.
- Bleeding — early, at the staple line or the anastomoses; the published frequency varies widely depending on the definition used. Male sex, revisional surgery, age and hypertension increase the risk in the bypass.
- Venous thrombosis and pulmonary embolism — a risk inherent to obesity and surgery, reduced with prophylactic anticoagulants, compression stockings and early walking.
- Nutritional deficiencies — iron, vitamin B12, vitamin D, calcium, folate, thiamine, zinc and copper; more intense after the bypass. They require supplementation and periodic tests for life.
- Reflux and esophagitis — more frequent after the sleeve (esophagitis in 31% at 10 years in SLEEVEPASS, versus 7% in the bypass); in some cases they require conversion to bypass.
- Dumping syndrome, hypoglycemia, gallstones and internal hernias — more characteristic of the bypass; gallstones are frequent during the phase of rapid weight loss.
- Weight regain and recurrence of associated diseases — possible with any technique, as the CFM warns; some patients need revisional surgery (15.8% to 22.1% of reoperations or interventions at 5 years in SM-BOSS).
- General risks — anesthesia, infection, hernia at the incisions and, rarely, stricture (narrowing) of the anastomosis, treated by endoscopic dilation.
Common questions about this procedure.
Who can have bariatric surgery?+
Under the CFM rule (Resolution 2,429/2025): BMI of 40 or more; BMI between 35 and 40 with a disease worsened by obesity; or BMI between 30 and 35 with specific conditions, such as type 2 diabetes or severe sleep apnea — always after failure of clinical treatment and with assessment by the multidisciplinary team. There is no maximum age in the rule; adolescents from the age of 16 follow adult criteria.
Which is better: bypass or sleeve?+
It depends on the patient. In randomized trials, the bypass produced slightly greater weight loss (about 7 to 8 percentage points of excess weight) and much better reflux control; the sleeve is simpler, preserves absorption and access to the stomach, but can worsen reflux. Diabetes remission was similar. Significant reflux, hiatal hernia and very high BMI favor the bypass; the decision is shared.
Is bariatric surgery dangerous? What is the risk of death?+
Perioperative mortality is between 0.03% and 0.2% according to the American and international societies — similar to that of other common abdominal operations. The most serious complications are leak and bleeding, both infrequent and detailed in the risks section. The risk is lower in hospitals with full facilities and an experienced team, as the CFM requires.
How is the surgery done? How long does it take?+
By laparoscopy or with the robot, through five or six small incisions, under general anesthesia. The sleeve takes around one hour; the bypass, one to two hours. The hospital stay is 2 to 3 days.
Is robotics better in bariatric surgery?+
There is no evidence of that. The 2024 meta-analyses, with tens of thousands of patients, showed equivalent complications, leaks, mortality and weight loss between robotics and laparoscopy, with longer time and higher cost for the robot; some observational studies suggest slightly less pain on the first day and less anastomotic stricture in robotic bypass, findings that need confirmation. Dr. Solon performs both techniques and reserves robotics for selected cases.
How much weight will I lose?+
On average, patients lose about half to two thirds of their excess weight: in the clinical trials, 49% (sleeve) and 57% (bypass) at 5 years, and 43.5% and 50.7% at 10 years. Maximum loss occurs between 12 and 24 months. The individual result depends on adherence to diet, physical activity and follow-up — and partial regain is possible with any technique.
Is diabetes cured by the surgery?+
Surgery is the treatment with the highest rate of type 2 diabetes remission, but remission is not a guaranteed cure. In the STAMPEDE trial, 29% of patients operated on by bypass and 23% by sleeve kept their blood sugar controlled without medication at 5 years, versus 5% with intensive medical treatment; at 10 years, in SLEEVEPASS, remission was 26% to 33%. Diabetes can return, and follow-up with the endocrinologist continues.
Is the bypass reversible? And the sleeve?+
The sleeve is irreversible, because part of the stomach is removed. The bypass can technically be reversed in exceptional situations, but it is not designed to be undone — reversal is a complex operation, reserved for serious complications.
Will I regain weight?+
The CFM requires that the patient be informed that recurrence of obesity is possible with any technique. In the 10-year trials, weight loss remained in the range of 43% to 51% of excess weight, which means most people keep a large part of the result, but a proportion regain weight. Adherence to follow-up, diet and physical activity is what weighs most.
Will I need to take vitamins forever?+
Yes. The American and British guidelines recommend nutritional monitoring at least yearly for life and replacement of vitamins and minerals — more intense after the bypass, in which absorption is reduced. Deficiencies of iron, B12 and vitamin D are the most common and are avoidable with follow-up.
Does the sleeve cause reflux? And dumping?+
The sleeve can worsen or cause reflux: in SM-BOSS, 31.8% of patients had worsening at 5 years, and in SLEEVEPASS 31% had esophagitis at 10 years. Those who already have significant reflux are usually advised to have the bypass. Dumping syndrome — malaise, sweating and dizziness after sweets or large meals — is more typical of the bypass, but can also occur after the sleeve.
How long is the rest period and the sick leave?+
Work without physical effort is usually resumed in 2 to 3 weeks; intense exercise and lifting, after 4 to 6 weeks. Sick leave is defined case by case.
Do you operate through the SUS, the Brazilian public health system?+
I do operate through the SUS. I am a Professor of Surgery at the School of Medicine of the Federal University of Uberlândia and I operate on patients at the university hospital, HC-UFU. The route, however, does not go through my private practice: to be operated on through the SUS you must go to the health post or Basic Health Unit nearest your home, be assessed by a doctor and, if surgery is indicated, be placed in your municipality's regulation queue. The surgeon does not choose who gets operated on through the SUS — the queue is followed strictly, according to SUS rules.
Hospital facilities in Uberlândia, Brazil.
Hospital Mater Dei Santa Genoveva
Av. Vasconcelos Costa, 967 — Martins, Uberlândia-MG
Open in Google Maps →Content reviewed by Dr. Solon Gonçalves Souza Menezes — CRM-MG 79366, RQE 60355 (GI Surgery), RQE 44656 (General Surgery). Professor of Surgery at FAMED-UFU and Supervisor of the General Surgery Medical Residency Program at HC-UFU. ORCID. Last reviewed: October/2026.
- Conselho Federal de Medicina. Resolução CFM nº 2.429, de 25 de abril de 2025 — normas seguras para o tratamento cirúrgico da obesidade e das doenças metabólicas (revoga a Resolução CFM nº 2.131/2015). Diário Oficial da União, 20 maio 2025. sistemas.cfm.org.br/normas/arquivos/resolucoes/BR/2025/2429_2025.pdf
- Conselho Federal de Medicina. Resolução CFM nº 2.470, de 18 de agosto de 2026 — altera o Anexo da Resolução CFM nº 2.429/2025 (equipe multiprofissional). Diário Oficial da União, 24 ago. 2026. sistemas.cfm.org.br/normas/arquivos/resolucoes/BR/2026/2470_2026.pdf
- Eisenberg D, Shikora SA, Aarts E, 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(12):1345-1356. doi:10.1016/j.soard.2022.08.013
- Peterli R, Wölnerhanssen BK, Peters T, 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(3):255-265. doi:10.1001/jama.2017.20897
- Salminen P, Helmiö M, Ovaska J, et al. Effect of Laparoscopic Sleeve Gastrectomy vs Laparoscopic Roux-en-Y Gastric Bypass on Weight Loss at 5 Years Among Patients With Morbid Obesity: The SLEEVEPASS Randomized Clinical Trial. JAMA. 2018;319(3):241-254. doi:10.1001/jama.2017.20313
- Salminen P, Grönroos S, Helmiö M, 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(8):656-666. doi:10.1001/jamasurg.2022.2229
- Lee Y, Doumouras AG, Yu J, et al. Laparoscopic Sleeve Gastrectomy Versus Laparoscopic Roux-en-Y Gastric Bypass: A Systematic Review and Meta-analysis of Weight Loss, Comorbidities, and Biochemical Outcomes From Randomized Controlled Trials. Ann Surg. 2021;273(1):66-74. doi:10.1097/SLA.0000000000003671
- Schauer PR, Bhatt DL, Kirwan JP, et al. Bariatric Surgery versus Intensive Medical Therapy for Diabetes — 5-Year Outcomes. N Engl J Med. 2017;376(7):641-651. doi:10.1056/NEJMoa1600869
- Zhao S, Fu Y, Zhou J, et al. Comparing the Efficacy of Robotic Versus Laparoscopic Sleeve Gastrectomy: A Systematic Review and Meta-Analysis. Obes Surg. 2024;34(9):3493-3505. doi:10.1007/s11695-024-07413-z
- Du X, Shen L, Xu S, et al. Primary Robotic Versus Conventional Laparoscopic Roux-en-Y Gastric Bypass in Morbidly Obese Patients: A Systematic Review and Meta-Analysis. Surg Laparosc Endosc Percutan Tech. 2024;34(4):383-393. doi:10.1097/SLE.0000000000001293
- Gagner M, Kemmeter P. Comparison of laparoscopic sleeve gastrectomy leak rates in five staple-line reinforcement options: a systematic review. Surg Endosc. 2020;34(1):396-407. doi:10.1007/s00464-019-06782-2
- Jung JJ, Jackson T, Gordon L, Hutter MM. Intraoperative leak test is associated with lower postoperative bleed rate in primary sleeve gastrectomy: a propensity matched analysis of primary and revision bariatric surgery using the MBSAQIP database. Surg Endosc. 2022;36(1):753-763. doi:10.1007/s00464-020-08264-2
- Parrott J, Frank L, Rabena R, et al. American Society for Metabolic and Bariatric Surgery Integrated Health Nutritional Guidelines for the Surgical Weight Loss Patient 2016 Update: Micronutrients. Surg Obes Relat Dis. 2017;13(5):727-741. doi:10.1016/j.soard.2016.12.018
- O'Kane M, Parretti HM, Pinkney J, et al. British Obesity and Metabolic Surgery Society Guidelines on perioperative and postoperative biochemical monitoring and micronutrient replacement for patients undergoing bariatric surgery — 2020 update. Obes Rev. 2020;21(11):e13087. doi:10.1111/obr.13087
- Mechanick JI, Apovian C, Brethauer S, et al. Clinical practice guidelines for the perioperative nutrition, metabolic, and nonsurgical support of patients undergoing bariatric procedures — 2019 update. Surg Obes Relat Dis. 2020;16(2):175-247. doi:10.1016/j.soard.2019.10.025