What is a Sleeve Gastrectomy (Gastric Sleeve Surgery)?

Gastric sleeve surgery, medically known as a sleeve gastrectomy, is a surgical procedure used to treat morbid obesity and support lasting weight loss. By removing a large portion of the stomach, its volume is significantly reduced. This naturally shrinks the patient's portion sizes and noticeably curbs their appetite. As one of the most frequently chosen methods in bariatric surgery, it does more than just help you lose weight—it also aids in managing metabolic conditions linked to obesity, such as type 2 diabetes and hypertension.

• The procedure is performed laparoscopically (a minimally invasive, closed method) through tiny incisions in the abdominal wall.
• Approximately 75 to 80 percent of the stomach is surgically removed.
• Because the section that secretes the hunger hormone (ghrelin) is taken out, appetite drops dramatically after surgery.
• The operation takes about 1 to 2 hours, and the hospital stay is usually 2 to 3 days.
• Recovery involves a special, dietitian-guided nutrition plan that progresses slowly from clear liquids to solid foods.

What is a Sleeve Gastrectomy?

A sleeve gastrectomy is a surgical procedure that alters the anatomical structure of the stomach, turning it into a thin, long tube roughly the shape of a banana. Often referred to simply as gastric sleeve surgery, this is a restrictive type of bariatric surgery. This means that the absorption pathway in your intestines is not altered in any way; only the physical food storage capacity of the stomach is limited.

Normally, a healthy adult's stomach can hold about 1.5 to 2 litres of food and liquid. After a sleeve gastrectomy, this volume drops to just 100 to 150 millilitres. One of the biggest advantages of this procedure is the complete removal of the upper part of the stomach, known as the 'fundus'. The fundus is the main production centre for ghrelin, the hormone that sends hunger signals to the brain. With this section gone, patients not only feel full after eating much smaller portions, but they also no longer experience those intense, gnawing hunger pangs between meals.

Because a sleeve gastrectomy leaves the intestinal anatomy untouched, it is generally considered a more physiological approach compared to gastric bypass surgeries. Your digestive system continues to follow its natural route. In the long run, this keeps the risk of severe vitamin and mineral deficiencies lower than it might be with other surgical methods.

Who is a Good Candidate for Gastric Sleeve Surgery?

Wondering who actually qualifies for a gastric sleeve is one of the most common questions we hear from people struggling with obesity. It is important to understand that this is not a cosmetic procedure; it is a medical treatment for morbid obesity, a condition that leads to serious health issues. Candidacy is based on Body Mass Index (BMI) criteria established by international health organisations.

Individuals with a BMI of 40 or higher are generally considered direct candidates for this surgery. If your BMI is between 35 and 39.9 and you also suffer from obesity-related comorbidities—such as type 2 diabetes, hypertension, sleep apnoea, severe joint problems, or a fatty liver—surgery may also be recommended. In recent years, some patients with a BMI between 30 and 35 who have uncontrolled diabetes are also being evaluated for this procedure under the umbrella of metabolic surgery.

Physical measurements alone are not enough to clear someone for surgery. A suitable candidate must have previously tried non-surgical methods like diet, exercise, and medical nutrition therapy without achieving lasting success. Furthermore, the patient must not have an alcohol or substance dependency and needs to be psychologically prepared to adapt to the significant lifestyle and dietary changes required after the operation.

Preparing for Surgery

A successful bariatric surgery requires a meticulous preparation phase. Once the decision is made, the patient undergoes a comprehensive health screening by a multidisciplinary team. This team typically includes a general surgeon, an endocrinologist, a cardiologist, a pulmonologist, a psychiatrist, and a bariatric dietitian.

During this prep phase, you will have detailed blood tests, a chest X-ray, an ECG, and an abdominal ultrasound. An endoscopy is also performed to check the inner lining of the stomach for ulcers, gastritis, hernias, or bacteria like Helicobacter pylori. When examining stomach conditions in detail, advanced endoscopic techniques that offer early detection of stomach and bowel cancer using staining methods can also be a guiding light to ensure your digestive system is healthy enough for the procedure. If any treatable condition is found in the stomach, medication is prescribed before the surgery.

About one to two weeks before the operation, you will start a special nutrition plan under your dietitian's guidance, often called a 'liver-shrinking diet'. Patients with obesity frequently have an enlarged, fatty liver. Because the liver sits right above the stomach, an enlarged liver can obstruct the surgeon's view during the operation. This short-term diet—low in carbohydrates and high in protein—shrinks the liver, making the laparoscopic surgery much safer and smoother.

How is the Surgery Performed and How Long Does It Take?

A sleeve gastrectomy is performed under general anaesthesia using a laparoscopic (closed) technique. Instead of making a large incision across the abdomen, the surgeon creates four or five tiny keyhole incisions, usually half to one centimetre in size. A thin tube with a high-definition camera at the tip, along with specialised surgical instruments, is inserted through these small openings. The abdomen is then gently inflated with carbon dioxide gas to give the surgeon a clear, spacious working area.

During the procedure, a calibration tube (bougie) is passed through the mouth and into the stomach. This tube acts as a guide to determine the width of the new stomach. Using a special device called a 'stapler'—which simultaneously cuts the tissue and seals it with tiny titanium staples—the surgeon separates and removes the larger portion of the stomach. Thanks to the guide tube, the remaining stomach is shaped into a narrow tube that functions as a direct continuation of the oesophagus.

The excised portion of the stomach is carefully removed through one of the small incisions. In the final stage of the surgery, a leak test is performed by introducing a special dyed liquid or air into the stomach to ensure the staple line is completely secure and there is no bleeding. Once everything is confirmed to be safe, the instruments are removed, and the incisions are closed with aesthetic stitches. Depending on the patient's anatomy, the entire process takes about 1 to 2 hours.

Diet and Recovery After Gastric Sleeve Surgery

In bariatric surgery, adapting to your new lifestyle post-operation is just as crucial as the surgery itself. The recovery process begins in the hospital; getting out of bed and walking just a few hours after surgery is a critical step to reduce the risk of blood clots and sluggish bowels.

Dietary Stages

Nutrition after a gastric sleeve relies on a strict, four-stage set of rules designed to help your body adapt to the stomach's new size and allow the staple line to heal. During the first week, you will consume only clear liquids like water, unsweetened apple juice, and clear broths. In the second week, you transition to thicker liquids such as protein shakes, lactose-free milk, and traditional Turkish ayran. By the third and fourth weeks, puréed foods (like blended vegetable soups, yoghurt, and soft cheeses) are introduced. At the end of the first month, you can begin eating soft solid foods. Once you transition to solids, the golden rule is to chew every bite at least twenty to thirty times and never mix solid foods with liquids (you must stop drinking liquids 30 minutes before and after meals).

The Healing Process

In the first few days after being discharged, it is completely normal to feel mildly fatigued and experience a slight ache around the incision sites. Patients who work desk jobs can usually return to work within 7 to 10 days, while those with physically demanding jobs are advised to wait 3 to 4 weeks. For the first six months, you must avoid heavy lifting and strenuous abdominal exercises. However, swimming, brisk walking, and light aerobics starting from the first month will greatly support your recovery and weight loss.

Potential Risks and Complications

When performed by experienced surgeons in fully equipped medical centres, a gastric sleeve is considered as safe as gallbladder surgery. However, like any major operation, it carries certain risks. The most prominent early-stage risks are bleeding and staple line leaks. A gastric leak occurs when stomach fluid seeps into the abdominal cavity through the staple line. It usually presents with palpitations, fever, and severe abdominal pain. If caught early, it can be treated with endoscopic methods or stent placements.

Long-term risks include vitamin and mineral deficiencies (particularly B12, iron, and vitamin D) due to reduced food intake, hair loss, and sagging skin resulting from rapid weight loss. Additionally, the rapid weight loss phase can increase the risk of gallstone formation. As experts point out, considering the fact that as gallstones get smaller, surgery becomes inevitable, your doctor will closely monitor your gallbladder health after the procedure. Some patients may also experience an increase in acid reflux symptoms post-surgery.

When to See a Doctor

Reading your body's signals correctly during your recovery at home is vital. While most complaints stem from simple gas pains or the difficulty of adjusting to a new diet, certain symptoms can be warning signs of serious complications requiring immediate medical attention.

If you experience any of the following symptoms, you should contact your surgeon without delay or go to the emergency department of the nearest fully equipped hospital:

• A high fever exceeding 38.5°C that does not come down.
• Severe abdominal or left shoulder pain that worsens and does not ease with painkillers.
• A resting heart rate spiking above 120 beats per minute (palpitations).
• Sudden difficulty breathing, chest pain, or feeling faint.
• Persistent nausea, vomiting blood, or passing tarry, black stools.
• Excessive redness, swelling, increased warmth, or foul-smelling discharge at the incision sites.

In such urgent and unexpected situations, you can call 112 for your safety or visit our Emergency Medicine department, which operates 24/7 with an expert team, ensuring that necessary tests and interventions are carried out swiftly.

The Bariatric Surgery Journey at BHT CLINIC

At BHT CLINIC İstanbul Tema Hastanesi, bariatric surgery is performed at international quality standards with JCI accreditation, using a patient-safety-first approach. Your journey is uniquely tailored for you by a multidisciplinary board where general surgery, endocrinology, nutrition and dietetics, and psychology departments work closely together.

All your pre-operative tests are completed swiftly under one roof using advanced medical technology. In the post-operative period, our bariatric dietitians and psychologists stand by your side with a long-term follow-up programme to help you achieve lasting weight control. For any potential needs, your health is secured with our 24/7 uninterrupted emergency department and intensive care units. To take the first step towards a healthier life and discuss your treatment options with our specialist physicians, you can book an appointment.

Frequently Asked Questions

How long does a gastric sleeve surgery take?

Depending on the patient's anatomy and the amount of intra-abdominal fat, the surgery itself is usually completed in 1 to 2 hours. The total time spent in the operating theatre may be slightly longer when factoring in anaesthesia preparation and waking up.

When can I return to work after surgery?

If you work a desk job or a role that is not physically demanding, you can usually return to work within 7 to 10 days after being discharged. However, those in jobs requiring heavy physical activity are advised to wait at least 3 to 4 weeks.

Will I gain weight again after gastric sleeve surgery?

The surgery is a highly powerful tool for weight loss, but it is not a standalone miracle. If a patient ignores the dietitian's guidelines, continuously consumes high-calorie liquids, and fails to exercise, the stomach may stretch slightly over time, leading to weight regain in the long run.

Will there be a scar?

Because the procedure is performed laparoscopically (closed method), it leaves only 4 to 5 tiny incision scars on the abdomen, each ranging from half to one centimetre. These scars fade over time and are generally not cosmetically bothersome.

Is it mandatory to take vitamins after bariatric surgery?

Yes. Because the stomach volume is reduced and food intake decreases, it becomes difficult to meet your body's daily vitamin and mineral needs through food alone. Based on blood tests conducted at intervals determined by your doctor, you will likely need to take regular vitamin supplements, especially during the first year.

This article is for informational purposes only; please consult your physician for diagnosis and treatment.