Bariatric surgery
Gastric sleeve
The most commonly performed weight-loss operation worldwide — and one that permanently removes part of the stomach.
What this treatment involves
A sleeve gastrectomy removes approximately 75–80% of the stomach along its outer curve, leaving a narrow tube roughly the shape and width of a banana. It is performed laparoscopically, through several small incisions.
Two things change. The stomach holds far less, so fullness arrives after a much smaller meal. And the removed portion is the main site producing ghrelin, a hormone involved in appetite, so many patients report feeling less hungry — an effect that varies between people and often lessens over time.
The digestive route itself is unchanged: food still passes through the stomach into the small intestine in the normal order. That makes it simpler than bypass surgery, with fewer long-term absorption problems, but it also means the removed stomach is gone permanently.
Who may be suitable
Surgeons generally consider weight-loss surgery where body mass index is above 40, or above 35 alongside a condition made worse by weight — type 2 diabetes, sleep apnoea, high blood pressure or severe joint disease. Some guidelines use lower thresholds in certain populations.
Those numbers are a starting point for a conversation, not a qualification. A full assessment looks at your medical history, previous surgery, medication, mental health, and whether other approaches have been tried and supported properly.
Uncontrolled eating disorders, untreated substance dependence and unmanaged severe mental illness are usually reasons to delay surgery rather than proceed, because the operation makes the following year harder, not easier. Pregnancy is contraindicated for at least 12–18 months afterwards.
Whether this operation is appropriate for you can only be determined by a qualified surgeon after an individual assessment. No form, calculator or photograph can answer it.
Why patients choose it
It is technically simpler than bypass surgery, takes less operating time, and does not reroute the intestine — which means fewer long-term risks of malabsorption and no internal hernia risk from rearranged anatomy.
Because the intestine is untouched, medication absorption is generally more predictable than after bypass, which matters for people on drugs with a narrow therapeutic range.
Where obesity-related conditions are present, improvement in blood-sugar control, blood pressure and sleep apnoea is well documented after significant weight loss — though the extent varies between individuals and is not guaranteed by the operation itself.
How treatment works
Assessment before you travel
Before departure
Medical history, medication, measurements and any obesity-related conditions are reviewed by the surgical team. Some patients are advised that surgery is not appropriate, or not yet.
Pre-operative tests in Istanbul
Day 1–2
Blood tests, ECG, chest imaging and endoscopy as indicated, plus consultations with the surgeon, anaesthetist and dietitian.
Surgery
Day 2–3
Performed laparoscopically under general anaesthetic, usually taking one to two hours.
Hospital stay
2–3 nights
Two to three nights, with mobилisation encouraged early and a leak check before discharge.
Recovery in Istanbul
3–5 days
Review with the surgical team, dietary guidance, and clearance to fly given by the surgeon rather than by your booking.
Lifelong follow-up
Ongoing
Blood monitoring and supplementation continue indefinitely, with dietetic support in the first year. This is part of the treatment, not an optional extra.
What happens in Istanbul
Weight-loss surgery requires a longer stay than most treatments — usually seven to ten days in Istanbul. Pre-operative tests and consultations with the surgeon, anaesthetist and dietitian happen over the first day or two. You spend two to three nights in hospital after the operation, then remain nearby for review before flying. Flying too early after abdominal surgery carries a raised risk of blood clots, so departure is confirmed by the surgical team rather than by a booking.
Recovery
Two to three nights in hospital, with walking encouraged within hours of surgery to reduce the risk of blood clots.
Diet progresses in stages under dietetic supervision — clear liquids, then full liquids, then puréed food, then soft food — typically over four to six weeks before normal textures are reintroduced. Eating too much or too quickly during this period causes pain and vomiting, and can damage the healing staple line.
Most people return to desk work in two to four weeks and to full activity, including exercise, at around six weeks. Fatigue during the first month is normal, since calorie intake is very low.
Risks and considerations
This is major abdominal surgery under general anaesthetic. Serious complications are uncommon but real, and include a small risk of death — quoted in large studies as well under one percent, but not zero.
The most serious specific complication is a leak from the staple line, which can require emergency surgery, intensive care and a prolonged stay. Bleeding, infection, blood clots in the legs or lungs, and narrowing of the sleeve are all recognised.
Reflux is the most common longer-term problem. A sleeve can cause new reflux or worsen existing reflux, sometimes enough to require conversion to a bypass later. If you already have significant reflux, this is a reason to discuss bypass instead.
The removed stomach cannot be restored. Nutritional deficiencies — particularly vitamin B12, iron and vitamin D — are common and require lifelong supplementation and blood monitoring. Weight regain is possible, particularly where eating patterns return; gallstones, hair thinning in the first months, and loose skin after substantial loss are all common. Excess skin frequently needs surgery of its own, which is a separate operation with its own risks and cost.
This information is general and educational. Whether a procedure is appropriate for you can only be determined by a qualified medical professional after an individual assessment, including your medical history and an examination.
Common questions
Can a gastric sleeve be reversed?
No. The removed portion of stomach is gone permanently. A sleeve can be converted to a different operation later — most often a bypass, usually because of severe reflux — but the original anatomy cannot be restored.
How much weight will I lose?
We do not publish a figure, because outcomes vary enormously and any number on a clinic page reads as a promise. Loss depends on your starting point, your metabolism, any medical conditions, and above all what changes afterwards. Your surgeon can discuss realistic ranges for someone in your situation — that is a conversation, not a marketing claim.
Will I need vitamins for life?
Yes, and blood tests to monitor them. Reduced stomach volume means less food and less acid, which affects absorption of B12, iron and vitamin D in particular. Deficiencies develop quietly and can cause lasting harm — nerve damage from untreated B12 deficiency is not reversible. Follow-up is part of the treatment.
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