Sleeve gastrectomy explained in detail: what it is, how it works, who is a candidate, what to expect before and after surgery. Comprehensive guide by Assoc. Prof. Dr. Hasan Abuoğlu, General Surgery.
Medically reviewed by Assoc. Prof. Dr. Hasan Abuoğlu · May 1, 2026
This article was reviewed on May 1, 2026 by Assoc. Prof. Dr. Hasan Abuoğlu, Associate Professor of General Surgery, in accordance with international IFSO and ASMBS 2022 clinical guidelines and current peer-reviewed literature.
Obesity is one of the most pressing health concerns of the modern era. When lifestyle modifications such as diet and exercise do not yield sufficient results, sleeve gastrectomy — also known as laparoscopic sleeve gastrectomy (LSG) or gastric sleeve surgery — has emerged as an evidence-based, effective surgical option. Sleeve gastrectomy currently accounts for approximately half of all bariatric and metabolic surgical procedures performed worldwide.
This comprehensive guide explains what sleeve gastrectomy is, how it is performed, who may be a candidate, the pre- and postoperative process, and answers the most frequently asked questions.
Sleeve gastrectomy is a bariatric surgery procedure in which approximately 75-80% of the stomach is surgically removed, leaving behind a banana-shaped or tube-shaped stomach. In medical literature, it is referred to as laparoscopic sleeve gastrectomy (LSG).
| Aspect | Detail |
|---|---|
| Medical name | Laparoscopic sleeve gastrectomy (LSG) |
| Other names | Gastric sleeve surgery, vertical sleeve gastrectomy |
| Mechanism | Restrictive (limits food intake) |
| Surgical approach | Laparoscopic (minimally invasive, through small incisions) |
| Procedure duration | Approximately 60-90 minutes |
| Hospital stay | Typically 2-3 days |
| Recovery period | 2-4 weeks |
Sleeve gastrectomy works through two primary mechanisms:
1. Restriction of food intake (mechanical effect): With a smaller stomach volume, the patient feels full after eating much smaller portions. The stomach volume reduces from approximately 1-1.5 liters preoperatively to about 100-150 ml postoperatively.
2. Hormonal changes (metabolic effect): The portion of the stomach that is removed produces a hormone called ghrelin, often referred to as the "hunger hormone." With most of the ghrelin-producing region surgically removed, patients experience a significant reduction in hunger sensation following the procedure.
The combination of these two mechanisms positions sleeve gastrectomy not only as a mechanical restrictive procedure but also as a metabolic surgical operation.
The volume of a normal adult stomach is approximately 1,000-1,500 ml. During sleeve gastrectomy, the greater curvature of the stomach (including the fundus and greater body) is removed, leaving a long and narrow tube extending from the stomach inlet to the outlet.
Following sleeve gastrectomy, the digestive process works as follows:
Important: Because sleeve gastrectomy does not alter intestinal anatomy, it is classified as a restrictive procedure, distinct from absorption-reducing operations such as gastric bypass.
Eligibility for sleeve gastrectomy is determined according to internationally recognized clinical guidelines issued by professional medical societies.
The joint guidelines published in 2022 by the American Society for Metabolic and Bariatric Surgery (ASMBS) and the International Federation for the Surgery of Obesity and Metabolic Disorders (IFSO) define the indications for metabolic and bariatric surgery, including sleeve gastrectomy, as follows:
| Body Mass Index (BMI) | Recommendation |
|---|---|
| BMI ≥ 35 kg/m² | Eligible regardless of presence of comorbidities |
| BMI 30-34.9 kg/m² | May be considered when metabolic disease (e.g., type 2 diabetes) is present |
| Asian populations BMI > 27.5 kg/m² | Lower threshold due to genetic and metabolic differences |
Historical note: The 1991 NIH Consensus Statement established BMI ≥ 40 (without comorbidities) or BMI ≥ 35 (with comorbidities) as the eligibility threshold. The 2022 ASMBS/IFSO update lowered these thresholds based on accumulated evidence demonstrating safety and long-term efficacy.
Body Mass Index is calculated as follows:
Example: A person weighing 95 kg and 1.70 m tall has a BMI of:
The following obesity-related conditions strengthen the indication for surgery:
The current ASMBS/IFSO guidelines support the following age groups, following appropriate evaluation:
In the following situations, sleeve gastrectomy is either contraindicated or other treatment options are explored first:
Clinical evaluation is essential: The lists above provide general guidance. Determination of individual eligibility is only possible after detailed medical evaluation and necessary investigations.
Sleeve gastrectomy is now performed almost exclusively using a laparoscopic (minimally invasive) approach. Open surgery is rarely used today, except in specific circumstances.
1. General anesthesia: The patient is placed under general anesthesia by the anesthesiologist.
2. Trocar placement: 5-6 small incisions (each 0.5-1.2 cm in size) are made in the abdomen for the placement of laparoscopic trocars.
3. Pneumoperitoneum: The abdominal cavity is insufflated with carbon dioxide to create working space for the surgeon.
4. Stomach exposure: The left lobe of the liver is retracted to expose the stomach.
5. Vascular dissection: Blood vessels along the greater curvature of the stomach (gastroepiploic artery branches) are carefully divided using advanced energy devices (LigaSure, Harmonic Scalpel).
6. Bougie placement: A calibration tube (bougie) is inserted by the anesthesiologist through the esophagus into the stomach. Standard bougie sizes range between 36-40 French (approximately 12 mm diameter), used to standardize the volume of the remaining gastric tube.
7. Stomach division with stapler: Using linear surgical staplers, the stomach is divided vertically along the bougie. This is typically completed in 5-7 stapler firings.
8. Specimen extraction: The removed portion of the stomach is extracted through one of the trocar sites.
9. Hemostasis and leak testing: The staple line is carefully inspected; reinforced or sutured if necessary. Some surgeons perform a leak test using methylene blue solution or intraoperative endoscopy.
10. Drains: In some cases, 1-2 drains may be placed.
11. Trocar removal and closure: The pneumoperitoneum is released, trocars are removed, and the small incisions are closed.
Modern sleeve gastrectomy procedures utilize the following technologies:
A standard, uncomplicated sleeve gastrectomy procedure typically lasts 60-90 minutes of operative time. This duration may vary based on:
Typical hospital stay following sleeve gastrectomy is 2-3 days:
| Day | Process |
|---|---|
| Day of surgery | Postoperative recovery, observation, pain control, sips of water (with surgeon's approval) |
| Day 1 | Liquid diet initiation, ambulation encouraged, leak test (if indicated) |
| Day 2 | Drain removal (if present), test results review, discharge planning |
| Day 3 | Most patients are discharged |
Hospital stay duration may vary based on the patient's recovery rate, return of bowel function, and pain control.
The preoperative process is critically important for successful surgery and rapid recovery.
The following workup is standard:
Blood tests:
Imaging:
Consultations:
Most centers recommend a 2-4 week liver-shrinking diet before surgery:
This diet helps reduce the size of the liver during surgery, improving surgical visualization and reducing complication risk.
Within the first 24-48 hours after surgery:
Postoperative nutrition follows a 5-phase progression:
| Phase | Duration | Content |
|---|---|---|
| Phase 1 | First 1-2 days | Water and warm clear fluids only |
| Phase 2 | Week 1 | Clear liquids (broths, vegetable broth, sugar-free tea) |
| Phase 3 | Weeks 2-3 | Pureed/semi-liquid soft foods |
| Phase 4 | Weeks 4-6 | Soft solid foods (eggs, fish, cheese) |
| Phase 5 | From week 6 onward | Normal-textured foods (small portions) |
| Period | Recommended activity |
|---|---|
| First week | Light walking (2-3 times daily, 5-10 minutes) |
| Week 2 | Longer walks, normal household activities |
| Weeks 3-4 | Cycling, light cardio, treadmill walking |
| From week 6 | With medical clearance: weights, yoga, swimming |
Note: Exercises that strain the abdominal area (e.g., sit-ups, heavy weightlifting, contact sports) should be deferred for at least 6-8 weeks.
After sleeve gastrectomy, lifelong multivitamin and mineral supplementation is recommended:
Periodic blood tests (at 3, 6, 12 months and annually thereafter) are used to monitor vitamin/mineral levels.
Expected weight loss following sleeve gastrectomy, as reported in international literature:
| Time period | Expected weight loss (% of Excess Weight Loss — EWL) |
|---|---|
| 6 months | 50-60% |
| 12 months | 60-70% |
| 18-24 months | 60-70% (typically the maximum point) |
| 5 years | 50-60% (long-term sustainability) |
Excess Weight = Current weight - Ideal weight
Important — Individual variability: The percentages above represent average outcomes from large cohort studies. Individual results vary based on starting BMI, lifestyle adherence, comorbidities, genetic predisposition, hormonal factors, and adherence to postoperative follow-up.
Sleeve gastrectomy may provide significant improvement in obesity-related conditions beyond weight loss. Reported improvement rates from long-term international studies include:
These rates summarize international literature; individual outcomes may vary.
Long-term success with sleeve gastrectomy requires integration with lifestyle change. A 2025 systematic review and meta-analysis published in Cureus (PRISMA 2020 compliant, 31 randomized trials, 2014-2025) demonstrated that structured lifestyle interventions (nutrition, exercise, behavioral therapy) added to sleeve gastrectomy resulted in 5-30% greater weight loss, improved BMI, and improved cardiometabolic profiles compared to usual care.
For this reason, the surgery should be regarded as a starting point. Without changes in eating habits, regular exercise, and behavioral patterns, sustaining long-term success becomes difficult.
As with any surgical procedure, sleeve gastrectomy carries potential risks. With modern laparoscopic technique and experienced teams, these risks are quite low, but not zero.
Detailed preoperative evaluation, an experienced surgical team, modern technology, close postoperative follow-up, and patient compliance significantly reduce complication risks.
In addition to sleeve gastrectomy, several other bariatric procedures are available. The comparison below highlights commonly used methods:
| Feature | Sleeve Gastrectomy | Gastric Bypass (RYGB) | Mini Gastric Bypass | Gastric Balloon |
|---|---|---|---|---|
| Approach | Restrictive + hormonal | Restrictive + malabsorptive | Restrictive + malabsorptive | Restrictive (temporary) |
| Anatomical change | Stomach reduction | Stomach + intestinal bypass | Stomach + intestinal bypass | No surgery |
| Reversibility | Not reversible | Not reversible | Relatively reversible | Fully reversible |
| Average duration | 60-90 min | 90-150 min | 90-120 min | 15-30 min |
| Hospital stay | 2-3 days | 3-4 days | 2-3 days | Often same day |
| Effect on reflux | May worsen in some cases | Improves reflux | Improves reflux | Limited effect |
| Type 2 diabetes effect | Significant improvement | More pronounced improvement | More pronounced improvement | Limited |
| Vitamin malabsorption | Less | More | More | None |
There is no universally "best procedure." The most appropriate option for each patient is determined through individualized evaluation. BMI, comorbidities, reflux history, age, sex, and patient preference are all considered.
No. Sleeve gastrectomy is not reversible because the removed portion of the stomach cannot be replaced. However, revision surgeries (e.g., conversion to gastric bypass) can be performed if needed.
Significant pain after laparoscopic surgery typically lasts the first 2-3 days and is controlled with pain medication. After the first week, pain decreases markedly.
Office workers can usually return after 2-3 weeks, while those in physically demanding jobs may require 4-6 weeks. The exact timing is determined based on medical evaluation.
Due to the rapid weight loss period, waiting at least 12-18 months is recommended. Contraception is important during this period. Pregnancy plans should be coordinated with multidisciplinary follow-up.
Temporary hair loss may occur between months 3-6 due to rapid weight loss. It typically resolves on its own within 6-9 months. Adequate protein intake and vitamin supplementation can minimize this.
Maximum weight loss occurs in the first 18-24 months. In subsequent years, some weight regain (averaging 5-10%) may occur. Lifestyle adherence, nutrition, and exercise habits are decisive factors.
Coverage varies by individual insurance policy and country. Patients are encouraged to consult their insurance provider for specific information.
Operative time averages 60-90 minutes; however, total time including OR entry, anesthesia induction, recovery, and observation can extend to 2.5-3.5 hours.
Sleeve gastrectomy is one of the most thoroughly researched and evidence-based modern bariatric surgical procedures. Appropriate indication, an experienced team, modern technology, and the patient's commitment to lifestyle change form the foundation of successful outcomes.
The surgery should be regarded as a starting point. Long-term success comes from healthy eating habits, regular exercise, vitamin/mineral supplementation, and consistent medical follow-up after surgery.
For detailed information and individualized evaluation, consultation with a general surgeon experienced in bariatric and metabolic surgery is recommended.
⚠️ Important Notice (in accordance with Turkish Healthcare Promotion Regulation, Official Gazette No. 33075, Article 7/k): Outcomes of any surgical or interventional procedure may vary from person to person. Patients are advised to obtain detailed consultation from their physician before undergoing any procedure.
Eisenberg D, Shikora SA, Aarts E, et al. 2022 American Society of 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 PMC9834364
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. JAMA Surg. 2022;157(8):656-666.
IFSO Consensus on Definitions and Clinical Practice Guidelines for Obesity Management — an International Delphi Study. Obes Surg. 2024. PMC10781804
The Impact of Sleeve Gastrectomy Combined With Lifestyle Interventions on Anthropometric and Health Outcomes in Adults: A Systematic Review and Meta-Analysis. Cureus. 2025. PMC12146907
Healthcare Advertising and Information Activities Regulation. Turkish Official Gazette, November 12, 2025, No. 33075.
Author and Medical Reviewer: Assoc. Prof. Dr. Hasan Abuoğlu — Associate Professor of General Surgery
Health Tourism Authorization Number: ST-2697 (Republic of Türkiye, Ministry of Health)
Published: May 1, 2026 Last updated: May 1, 2026 Editorial contact: contact@drhasanabuoglu.com
This content is for informational purposes only and does not substitute for medical advice, diagnosis, or treatment. Always consult a qualified healthcare provider for medical decisions.
Assoc. Prof. Dr. Hasan Abuoğlu
General Surgery · Bariatric and Metabolic Surgery
General surgeon with over 25 years of experience and 10,000+ laparoscopic bariatric procedures. IFSO member.
Medical Disclaimer: This content is for informational purposes only. Please consult your doctor for personal medical advice.
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For detailed information about bariatric and metabolic surgery procedures, you may use the contact channels below. Initial consultations for international patients can be arranged remotely via video call or WhatsApp.
Assoc. Prof. Dr. Hasan Abuoğlu
Associate Professor of General Surgery
