Approximately ¾ of the stomach is removed during this procedure. By volume, this ratio is about 800-2000 cc (4-10 glasses of water). The remaining stomach has a capacity of 80-120 cc (half a glass of water).

After sleeve gastrectomy, weight loss occurs with 2 mechanisms :

1. Weight loss as a result of a mechanical limitation and a decrease in stomach motions due to a reduction in gastric volume.
2. Weight loss happens as a result of a hormonal alteration because the stomach tissue that makes ghrelin is eliminated.
3. Ghrelin is a hormone produced by oxyntic cells in the upper part of the stomach called the fundus and strongly stimulates the appetite center in the brain. Each gram of the gastric fundus contains 10-20 times more ghrelin than the duodenum. In other words, 80% of the Ghrelin hormone secreted in the whole body is secreted from the part of the stomach we call Fundus, which is removed by Tube Stomach Surgery. Because the fundus area of the stomach, where ghrelin is produced, is eliminated in Gastric Sleeve Surgery, appetite reduces and weight loss happens.

• It can be performed laparoscopically (closed), so wound healing is faster, pain is less, and the hospital stay is shortened.
• The stomach's capacity is reduced, but because its functions are unaffected, numerous food categories can be taken in moderation.
• Since the fundus region of the stomach, where ghrelin (hunger hormone) is produced, is removed, appetite also decreases and weight loss occurs.
• Dumping syndrome is avoided because the pylorus valve, which allows food to pass through the stomach slowly and hence aids digestion, is intact. In comparison to other procedures, the sense of fullness lasts longer since the food exits the stomach later. After gastric bypass surgery, dumping syndrome might occur.
• Since the intestine is not touched in this surgery, risks such as intestinal obstruction, stenosis, ulcer, anemia, protein and vitamin deficiency, osteoporosis (bone loss) that can be seen in by-pass surgeries are eliminated.
• It gives very effective results for the first stage surgery in consecutive double surgeries in supermorbid obese (BMI> 50 kg/m2).
• Because bypass surgery is dangerous in obese individuals with persistent inflammatory bowel disease (Crohn's disease, for example), sleeve gastrectomy surgery is a better option.

• The expected weight loss is generally achieved with sleeve gastrectomy surgery. However, ideal weight loss may not be achieved in “Sweat Eater” patients, who are known for their fondness for sweet foods. In such patients, a detailed evaluation should be made by a dietitian and psychologist before the operation and their eating habits should be changedIf a patient's food habits cannot be modified. By-pass or duodenal switch surgery may be considered instead of a tube stomach.
• With Tube Stomach Surgery, Diabetes is improved by 40-60%, Hypertension is improved by 60-70%, and the person does not need to use medication. However, in such chronic diseases called Gastric Bypass, Roux-en-Y surgery or another version of Mini Gastric By Pass is much more effective and 90% drugs are not needed.

Although weight loss varies from person to another, most people lose roughly 15 kg in the first month after a sleeve gastrectomy. In the second month, you'll lose 8-10 kg, 5-6 kg in the third month, and 4-5 kg in the months after that. It's not a good idea because quick weight reduction leads to vitamin deficits and sagging skin. The goal should be to achieve 70-80% of the optimal weight in the first six months, and to achieve the ideal weight after two years.

Drinking a colored liquid (methylene blue or contrast) 24 hours following the operation is used to perform a "leakage" test. Despite the low likelihood of leaking, after this test, the first sip of water is taken on the second day, followed by fruit juice, compote juice, and fruit teas. On the third day, grain-free soup, ayran, and yoghurt are introduced. Every day, depending on the person's cooperation, more foods are added to the diet. After a week, you can eat boiled veggies and fruits. In the second week, you can consume soft-boiled eggs, fish in the third week, and minced meat in the fourth week Patients progressively convert to purees in the third week after surgery, followed by a liquid food diet for 1-2 weeks, and then solid foods at the end of the first month. All foods are allowed to be eaten after 6 weeks, with the exception of chocolate. Overall, food consumption is drastically reduced. The portions are getting smaller. It becomes more vital to chew for longer periods of time. The key difference between diets without surgery and diets that assist the patient lose weight is the decrease in appetite. In the first few months, this effect is substantially stronger. Some people may lose interest in meals and sweets that they previously enjoyed.

Potential dangers and unfavorable outcomes can be seen in sleeve gastrectomy surgery, as they are in practically any procedure. In this sense, the surgeon's knowledge and experience are critical. However, there are some unfavorable outcomes that might occur with sleeve gastrectomy procedures:

• Leakage formation: The probability of this complication varies between 2 and 4%. Gastric sleeve surgery is performed by cutting the stomach with titanium alloy instruments called staplers. If this stapler line breaks during cutting, it will cause leaks (leakage or fistula). This can cause inflammation of the peritoneum (peritonitis), infection and abscesses. It is necessary to check for leakage before beginning the post-operative feeding. (leakage)
• Bleeding at the staple line: This is a condition that occurs around 1% during or after surgery and often resolves on its own. To control this, a reservoir (drain) is placed in the abdomen adjacent to the stapler line. If large amounts of blood fill this reservoir after surgery, it may be necessary to insert blood. This is ,  however, quite uncommon.
• Infection: It is more common especially in obese people with diabetes.
• Emboli: It is the most serious and deadly complication seen less than 1%. It is the situation where the clot formed in the veins breaks off from where it is and comes to the lungs or other organs and clogs them. In order to prevent this fatal complication, blood thinners are started 12 hours before the surgery (1 week and 10 days before as BMI rises). It is continued until 5 days after the operation. The risk of embolism continues until the 20th day after surgery. Antiembolic stockings, which are worn around the leg, are another common way to lower the risk of embolism.
• Respiratory problems : Smoking exacerbates the deterioration of lung capacity that has already occurred as a result of obesity. To reduce respiratory distress, the patient should cease smoking at least 10 days before the procedure and, if possible, begin respiratory excisions 10 days before the procedure. Triflow respiratory exercise devices, which are available for this purpose, provide a lot of advantages.
• Incisional hernia (incisional hernia): Since the area where the cut stomach is removed during the surgery is opened slightly wider, herniation may occur here. The incision should be sutured at the end of the surgery to avoid this.
• Organ injuries: Liver, lung and intestinal injuries may develop during surgery due to their proximity to the surgical field.
• Death: Sleeve gastrectomy surgery carries a 1 in 1000 chance of death. This risk is comparable to the chance of death associated with appendicitis or gallbladder surgery, and it is within acceptable limits

Skin sagging: this is a condition that develops in most patients. Rapid weight loss, age, sports and exercises can affect these sagging. If necessary, correction operations can be performed with plastic and reconstructive surgery.

Hair loss: Rapid weight loss after surgery might cause thinning and breakage of hair strands. It is a condition that occurs rarely as a result of a protein or trace element shortage.

Vitamin-mineral deficiency: In order to prevent this undesirable situation, although rarely, after sleeve gastrectomy; Preparations containing especially B1, B12 and D vitamins should be added to the treatment, albeit temporarily. In fact, it is necessary to control the blood levels of these vitamins and trace elements with regular blood tests.

The criteria of the World Obesity Surgery Association serve as a guide in this regard. Obesity surgery is indicated for patients with a BMI of more than 35 kg/m2 and co-morbidities (hypertension, diabetes, high cholesterol, polycystic ovarian syndrome, reflux esophagitis, etc.) or a BMI of more than 40 kg/m2. Another requirement, in addition to weight, is the lack of an advanced psychological condition. Furthermore, while the age limit has been substantially loosened in recent years, it should not be less than 16 years old and no more than 65 years old.