What Is Sleeve Gastrectomy? Everything You Need to Know from A to Z

Sleeve gastrectomy is a surgical obesity treatment in which a large portion of the stomach is removed to reduce its volume. Also known as gastric sleeve surgery, the operation can help a person feel full on smaller portions. However, it is not suitable for everyone who is overweight.

So who is sleeve gastrectomy for, how many hours does it take and what happens afterwards? In this guide, we cover everything you may be wondering about, from how the operation is performed and its risks to the recovery period and post-operative diet.

What Is Sleeve Gastrectomy and Why Is It Performed?

Sleeve gastrectomy is a bariatric (obesity) surgery procedure in which approximately 80% of the stomach is surgically removed. The remaining stomach takes the shape of a narrow, elongated tube, or "sleeve". For this reason, the procedure is also commonly referred to as stomach reduction surgery.

We can list the two main effects of the surgery as follows:

• Reduced stomach volume: The amount of food a person can eat in a single meal becomes smaller.
• Changes in appetite and satiety mechanisms: The surgery can lead to changes in the hormones that influence the feeling of hunger.

Sleeve gastrectomy generally does not change the natural route of food through the intestines. However, because the removed stomach tissue cannot be restored, the procedure is permanent.  

Who Is Sleeve Gastrectomy For?

The answer to the question "Who is sleeve gastrectomy for?" depends not only on a person's weight but also on their body mass index (BMI), health status and previous treatment experience.

According to current international bariatric surgery guidelines:

• If your BMI is 35 or above: Bariatric surgery may be recommended even in the absence of related health conditions.
• If your BMI is between 30 and 34.9: Surgery may be considered, particularly for people with metabolic diseases such as type 2 diabetes or those who have not achieved adequate results with non-surgical methods.
• If there are special health circumstances: The decision to operate is made on an individual basis following a multidisciplinary specialist assessment.

You can learn more about this topic by reading our article Who Is Sleeve Gastrectomy For? 7 Key Points. 

These criteria provide a general framework for bariatric surgery, but which surgical method is appropriate should be assessed separately.

How Much Do You Need to Weigh to Have Sleeve Gastrectomy?

There is no single weight threshold that everyone must reach to qualify for sleeve gastrectomy. Instead, BMI, which is calculated from height and weight, is taken into account.

BMI = Weight (kg) / Height (m)²

For example, for a person who is 1.70 meters tall:

• At 87 kilograms, BMI is approximately 30.
• At 101 kilograms, BMI is approximately 35.
• At 116 kilograms, BMI is approximately 40.

These figures are calculation examples only. On their own, they do not indicate eligibility for surgery.

What Are the Criteria for Bariatric Surgery?

When assessing eligibility for bariatric surgery, the following factors may be taken into account:

• BMI and the severity of obesity
• Related conditions such as type 2 diabetes, high blood pressure and sleep apnea
• Previous weight-loss attempts
• Eating habits
• Psychological and behavioral assessment
• Surgical and anesthetic risks
• Commitment to a long-term follow-up program

The decision on whether a person is suitable for surgery should be made by a general surgeon and the relevant healthcare team.

How Is Sleeve Gastrectomy Performed?

"How is sleeve gastrectomy performed?" is one of the questions people researching the operation ask most often. The surgery is usually performed under general anesthesia using a laparoscopic, or minimally invasive (keyhole), technique.

The main stages of the operation are as follows:

1. Several small incisions are made in the abdomen.
2. The stomach is accessed with the help of a camera and surgical instruments.
3. A large portion of the stomach is divided and removed using special surgical devices.
4. The remaining stomach tissue is left in the shape of a long, narrow tube.
5. The surgical team completes the necessary checks and finishes the procedure.

No permanent tube is placed in the stomach during the operation. The name "sleeve" comes from the shape of the remaining stomach.

How Long Does Sleeve Gastrectomy Take?

The answer to the question "How many hours does sleeve gastrectomy take?" can vary depending on the patient's health and the specifics of the operation. The surgery itself can usually be completed in approximately 1–2 hours. However, the total time spent in hospital is longer due to anesthesia preparation, pre-operative procedures and post-operative observation.

Previous abdominal surgery or the need for additional surgical procedures can also affect the length of the operation.

The Most Common Question: Is Sleeve Gastrectomy Dangerous?

When asked "Is sleeve gastrectomy dangerous?", it would be wrong to answer that it is a risk-free procedure. Sleeve gastrectomy is an obesity treatment that can deliver effective results in suitable patients. However, like any surgical procedure, it carries a risk of complications.

Possible risks of the surgery include:

• Bleeding
• Infection
• Leakage from the stomach suture or staple line
• Blood clot formation in the veins
• Narrowing of the stomach (stricture)
• Development of reflux or worsening of existing reflux
• Dehydration and nutritional deficiencies
• Vitamin and mineral deficiencies

The level of risk varies depending on the person's health, the specifics of the operation and the experience of the surgical team.

Related article: Gastric Balloon or Sleeve Gastrectomy? What You Need to Know Before Deciding

What Are the Signs of a Leak After Sleeve Gastrectomy?

In this context, a leak is when stomach contents seep from the surgical closure line into the abdominal cavity. Although rare, it is a serious complication.

If any of the following symptoms appear after surgery, it is extremely important to seek medical assessment without delay:

• Severe or steadily worsening abdominal pain
• Fever
• A noticeably rapid heart rate
• Shortness of breath
• A sudden deterioration in general condition

These symptoms are not caused only by a leak, but they may require urgent assessment.

What Should You Pay Attention to Before Sleeve Gastrectomy?

Pre-operative preparation is important for assessing surgical risks and for adapting to the post-operative period.

During this process, typically:

• Blood tests and any necessary imaging are carried out.
• The heart and respiratory system are assessed.
• Current medications are reviewed.
• Eating habits are examined.
• A psychological assessment is carried out where necessary.
• Smoking and other risk factors are addressed.

Some patients may follow a special diet before surgery aimed at reducing liver volume. However, any pre-operative changes to diet or medication should be made under the guidance of the healthcare team, not on the person's own initiative.

What Is Recovery Like After Sleeve Gastrectomy?

The recovery time after sleeve gastrectomy is not the same for everyone. A short period of monitoring in hospital may be needed after surgery. During this time, pain control, fluid intake, mobility and any signs of complications are monitored.

The key points to keep in mind during recovery are:

• Starting early, light walks as recommended by your doctor
• Managing fluid intake according to your healthcare team's plan
• Waiting for your surgeon's approval before heavy lifting and strenuous exercise
• Not moving through the dietary stages too quickly
• Not missing follow-up appointments

The time it takes to return to daily life and work may vary depending on the physical demands of the job and the person's recovery.

What Should Your Diet Be Like After Sleeve Gastrectomy?

Because the stomach volume is reduced after surgery, the diet is introduced in stages. The diet after sleeve gastrectomy generally consists of the following phases:

1. Liquid phase

In the first stage, clear liquids approved by the surgical team are consumed, followed by more nourishing liquids. Liquids should be sipped slowly in small amounts.

2. Puréed phase

When deemed appropriate, the patient moves on to smooth-textured foods. Yogurt, well-prepared vegetable purées and protein sources recommended by the dietitian can be used during this phase.

3. Soft food phase

As recovery progresses, soft foods that are easy to chew can be added.

4. Transition to solid foods

Solid foods are gradually introduced into the diet. Small portions, thorough chewing and adequate protein intake are important. The duration of these stages varies by hospital and individual. The program provided by the surgeon and dietitian should be followed.

What Should a Sample Menu Look Like After Sleeve Gastrectomy? 

For people looking for a sample menu after sleeve gastrectomy, the key point is that the menu should be tailored to the stage of recovery. For example, the daily diet of someone who has completed the transition to solid foods and has been cleared by their dietitian may include the following options:

• Breakfast: Eggs and low-fat cheese
• Lunch: Well-cooked fish or chicken with suitable vegetables
• Snack: Unsweetened yogurt
• Dinner: A source of protein and well-cooked vegetables

This is only a sample list showing types of food; it is not a personal diet plan with portion sizes and protein targets. Some of these foods may not be suitable in the early post-operative period.

Why Is Protein Important After Sleeve Gastrectomy?

Protein is important for tissue repair and for preserving muscle mass after surgery.

Because the stomach volume is reduced, getting enough protein can become difficult for some people. For this reason, the dietitian plans protein sources and, if necessary, supplements according to the person's needs. Monitoring nutrients such as vitamin B12, iron, calcium and vitamin D after surgery is also important. Supplements should be taken based on blood test results and the doctor's recommendations.

Does Sleeve Gastrectomy Leave Scars?

With the minimally invasive technique, sleeve gastrectomy scars may form where the small incisions were made on the abdomen. The appearance of the scars varies depending on the following factors:

• The number and size of the incisions
• Skin type
• Individual wound-healing characteristics
• Infection or wound-healing problems
• Surgical technique

Surgical scars may become less noticeable over time. However, there is no guarantee that they will disappear completely.

How Much Weight Can You Lose After Sleeve Gastrectomy?

• Weight loss after sleeve gastrectomy varies depending on the person's starting weight, metabolic status and post-operative habits.
• Weight loss usually becomes noticeable within the first year. However, it is not accurate to judge the success of the surgery solely by the change on the scales.
• Indicators such as blood sugar control, blood pressure, mobility and quality of life are also important.
• After surgery, weight loss may slow down, or some weight may be regained over time.

Can the Stomach Stretch Again After Sleeve Gastrectomy?

Some stretching of the remaining stomach tissue may occur over time after surgery.

However, weight regain cannot be explained by stomach stretching alone. Eating habits, hormonal changes, physical activity and other health factors can also play a role. This is why long-term follow-up after sleeve gastrectomy is important.

What Is the Difference Between Sleeve Gastrectomy and a Gastric Balloon?

Sleeve gastrectomy and a gastric balloon are different weight management methods.

• Sleeve gastrectomy: A surgical procedure in which part of the stomach is permanently removed.
• Gastric balloon: A non-surgical method in which a balloon is temporarily placed in the stomach to increase the feeling of fullness.

Sleeve gastrectomy can generally provide greater and longer-lasting weight loss. However, it carries surgical risks. A gastric balloon, on the other hand, has different eligibility criteria and its own specific risks.

Which Doctor Should You See for Sleeve Gastrectomy?

For sleeve gastrectomy, you can consult a general surgeon experienced in bariatric and metabolic surgery.  When choosing a surgeon and healthcare facility, you should consider not only the operation itself but also the pre-operative assessment and long-term follow-up services.

In particular, it can be helpful to find out the answers to the following questions:

• What is the surgeon's experience in bariatric surgery?
• Does the hospital have the facilities to manage complications?
• Is dietitian support provided after surgery?
• How are long-term follow-up appointments planned?
• Which healthcare team can be contacted in the event of complications?

If you are considering getting an expert opinion on sleeve gastrectomy, you can research healthcare facilities offering bariatric surgery on MediFinder and compare your options.

At what age can sleeve gastrectomy be performed?

The decision to operate is not based on age alone. In adults, overall health and surgical risks are assessed. In selected adolescent patients, surgery may also be considered at specialized centers within specific criteria.

When can you return to work after sleeve gastrectomy?

The time it takes to return to work depends on the person's recovery and the physical demands of their job. Returning to a desk job and returning to physically demanding work may not happen within the same timeframe.

Can you exercise after sleeve gastrectomy?

Yes. However, light walking is preferred in the early period. Your surgeon's approval should be obtained before starting strenuous exercise and weight training.

Does hair loss occur after sleeve gastrectomy?

Some people may experience temporary hair loss associated with rapid weight loss, inadequate protein intake or nutrient deficiencies. If hair loss is significant, you should consult your healthcare team.

Can sleeve gastrectomy be reversed?

No. The removed part of the stomach cannot be restored. For this reason, alternatives, possible benefits and risks should be carefully assessed before deciding on surgery.

Do you need to take vitamins after sleeve gastrectomy?

Usually, yes. The type and dose of vitamin and mineral supplements are determined according to the post-operative follow-up program and blood test results.

Is sleeve gastrectomy the same as gastric bypass?

No. In sleeve gastrectomy, part of the stomach is removed, whereas gastric bypass changes the connections between the stomach and the small intestine. The two methods have different advantages and risks.

Is weight loss guaranteed after sleeve gastrectomy?

No. The surgery can support significant weight loss, but results vary from person to person. Long-term success requires a healthy diet, physical activity and regular medical follow-up.

This content is for general information purposes only. The decision to undergo bariatric surgery requires an individual specialist assessment.

For a closer look at eating after surgery, see our guide Gastric Sleeve Diet: What to Eat After Sleeve Gastrectomy.