Obesity & Metabolic Surgery Center
The operation takes about an hour. Everything that decides whether it worked happens either before it or in the years afterwards.
About This Center
An hour is roughly what the operation takes.
Everything that decides whether it worked happens either before it or in the years afterwards, which is why this is organised as a unit and never as a theatre list. An assessment that finds the reason a previous attempt failed, whether that was an undiagnosed thyroid problem, a drug that causes weight gain, sleep apnoea nobody looked for, or an eating pattern that no operation on the stomach was ever going to reach. A choice between operations that produce roughly the same weight loss and entirely different problems, so that the decision turns on which set of long term difficulties fits your life least badly rather than on which promises the bigger number. A blood test at twelve months that catches something you cannot feel, and would not feel for years, until the damage it was doing quietly announced itself in a way that cannot be undone. None of that fits into a package of flights and a hospital night, and all of it is what a unit is for. That is the whole argument.
Free consultation
Send your height, weight and the last set of bloods
Start with your height and current weight, your highest ever weight, and the most recent blood results you hold, particularly HbA1c, liver function, vitamin D, ferritin and vitamin B12. Tell us which conditions you are being treated for and list every medication with its dose, since diabetes drugs and blood pressure drugs are often reduced within days of surgery and the plan for that is written in advance. Say whether you have ever had a weight loss operation, an intragastric balloon or an endoscopy, and what any of them showed. Tell us whether you take a GLP-1 medication now or have taken one, and for how long, because that changes the assessment without ruling anything out. Describe your reflux honestly, including how often you take anything for it, since that single answer moves the choice of operation more than almost any other.
What a unit is, beyond the theatre
Obesity is not a surgical disease that happens to be treated by other means. It is a chronic metabolic condition, and surgery is the most effective single intervention currently available for it, which is a different claim from saying surgery is the treatment. The distinction shows up in how care is organised. A unit built around this understanding contains a surgeon and also an endocrinologist, a specialist dietitian, a psychologist, an anaesthetist experienced with these patients, and an endoscopy service, and the surgeon is one voice among several and never the person selling the product. Voices, plural. Ask who else is in the room. Why that matters is easiest to see in what the other members actually do. The endocrinologist looks for the treatable causes and contributors that get missed, meaning thyroid disease, the drugs that cause weight gain, sleep apnoea and insulin resistance, and plans how diabetes and blood pressure medication will be reduced in the days after the operation, which happens fast enough to be dangerous if nobody has written it down. The dietitian establishes what you actually eat now, which a form never captures, and prepares you for a stomach that holds a small cupful. The psychologist looks for binge eating, for the use of food to manage distress and for expectations that surgery cannot meet, none of which are disqualifications and all of which change the plan.
One version of this argument is uncomfortable and worth stating directly, since it applies to a large part of the international market. An operation delivered as a package, with no assessment worth the name beforehand and no arrangement for the years afterwards, is the surgical part of the treatment sold as the whole of it.
Competently done, usually.
What is missing is everything that turns a competent operation into a good outcome five years later, and the missing part is invisible at the point of purchase. You cannot see what is missing. Nobody itemises an absence.
Surgery is one option now
Five years ago a page like this would have moved straight from the diagnosis to the operations.
Arrival of the GLP-1 medications changed the conversation, and a unit that does not discuss them with you is either out of date or has an interest in not raising them. Ask about them anyway.
That comparison now has real duration behind it. A study of health records from Israel matched 2,721 pairs of adults with obesity and diabetes, one of each pair starting a GLP-1 medication and the other having metabolic surgery, and followed them for up to twelve and a half years with a mean of six and a half. Surgery produced greater early reductions in body mass index and in HbA1c. The medication produced more modest effects that were sustained over time. That is a fair summary of where the evidence sits, and it is more useful than either the claim that drugs have made surgery obsolete or the claim that drugs are a passing fashion. What follows in a consultation is a genuine choice, and no funnel. Some people are better served by medication, particularly where the excess weight is moderate, where an operation carries specific added risk, or where the person simply does not want surgery, which is a complete reason. Some are better served by an operation, particularly where the weight is substantial, where diabetes has been present for years, or where medication has been tried and either failed or proved intolerable. Some do both, with medication used before surgery to reduce the size of the liver and the risk of the anaesthetic, or introduced afterwards at the point where weight begins to return and the alternative would be a second operation. A unit that presents all three routes is doing its job. Three routes, one conversation. Expect all three.
Which operation, and what differs
Here is the finding that reorganises this decision. Across the main operations the weight loss at the end is broadly similar, and what differs is which problems you get. A meta-analysis of 24 randomised trials covering 2,890 people compared gastric bypass against sleeve gastrectomy. In the first year the bypass gave better cholesterol figures, better blood sugar control, lower inflammation and higher rates of diabetes remission. Those advantages persisted into the middle years, particularly for cholesterol. At ten years there were no differences between the two procedures at all, and the authors concluded that the choice should be made individually.
This table scrolls sideways on a narrow screen. Swipe or drag to see every column.
| Operation | What it does, and what it commits you to |
|---|---|
| Sleeve gastrectomy | Around four fifths of the stomach is removed, leaving a narrow tube. No rerouting of the bowel, so absorption is largely preserved and the anatomy stays accessible to an endoscope. Reflux is the characteristic problem and it can worsen or appear for the first time, which is why existing reflux weighs heavily against this choice. |
| Roux-en-Y gastric bypass | A small pouch is joined directly to the small bowel, bypassing the rest of the stomach. Better early control of blood sugar and cholesterol, and it usually improves reflux instead of causing it. The costs are lifelong vitamin and mineral supplements, a risk of internal hernia years later, and dumping syndrome after sugary food. |
| One-anastomosis gastric bypass | A simpler bypass with a single join. Weight loss matches the standard bypass at one and three years. Iron deficiency is commoner, at 20 percent against 6 percent at a year in one comparison, and bile reflux is its characteristic complication, while internal hernia belongs to the standard bypass instead. |
| Revision surgery | Converting one operation into another, most often a sleeve to a bypass for reflux or for weight regain. Technically harder than a first operation, with higher complication rates, and it needs the original operative note. Anybody considering a first operation should know revision exists and is not a failure. |
The practical rule that comes out of all this is unglamorous. Since the weight loss is broadly similar, the operation should be chosen by which set of problems suits your life least badly. Significant reflux points away from a sleeve. A job or a home far from medical care points away from operations with a higher chance of needing an urgent reoperation years later. A history of taking tablets unreliably points away from the operations that depend most heavily on lifelong supplements. None of that is visible on a price list, and all of it is a conversation. Reflux is the question that matters most.
Why it is called metabolic
Metabolic in the name is not decoration.
These operations change blood sugar control within days, long before meaningful weight has been lost, through effects on gut hormones and bile flow, and not through eating less. That is why they are offered to people with type 2 diabetes at weights that would not previously have qualified, and why the field renamed itself. The name is a claim about mechanism. Not marketing.
To understand the size of that effect you need to know what happens without surgery, and a large study supplies it. Records from six American health systems covering 556,758 adults with type 2 diabetes, deliberately excluding anyone who had bariatric surgery, found that over three years only 2.9 percent achieved remission, defined as HbA1c below 6.5 percent sustained for at least three months off all glucose-lowering medication. Of those who did reach remission, 36.9 percent relapsed. Three things predicted it.
- Being on no glucose-lowering medication at the outset instead of three or more, which carried by far the strongest association.
- An HbA1c already below 7 percent rather than above 11 percent.
- Diabetes diagnosed within the past year instead of four years ago or longer.
Read that as the baseline against which surgical remission rates should be judged. It also carries a warning that applies directly to you. The people most likely to achieve remission were those earliest in the disease and on the fewest medications, which means the value of metabolic surgery is highest before diabetes has been present for many years, and falls as the pancreas loses function. Waiting is not neutral, since every year of diabetes costs some of the pancreatic function that a good result depends on, and the operation that would have worked at year two works less well at year eight. Anybody with type 2 diabetes considering this should be told what their duration of diabetes and current medication list imply about their chances, in numbers, before deciding. Waiting has a cost.
What happens before the operation
The assessment takes several days and it is the part most often compressed to nothing. Each step exists because it changes something. Nothing here is ritual.
Endoscopy and a look at the oesophagus
A camera examination of the stomach before deciding. It finds hiatus hernia, inflammation from reflux, and the changes in the lower oesophagus that argue firmly against a sleeve. It also finds Helicobacter, which is treated with a course of antibiotics before any operation is scheduled, since leaving it in place raises the risk of ulcers at a new join afterwards. This single test changes the operation in a meaningful minority of people.
Sleep, heart and lungs
Obstructive sleep apnoea is common in this group and frequently undiagnosed, and treating it before an anaesthetic reduces risk considerably, which is why it is looked for early. Where the symptoms suggest it, a sleep study is arranged before anything is booked, since an untreated airway is one of the few things that genuinely changes the risk of the anaesthetic. Heart and lung assessment is matched to your history rather than done as a ritual.
Baseline bloods, so later results mean something
Vitamin D, B12, ferritin, folate, calcium, parathyroid hormone, thyroid function, liver function and HbA1c are measured before anything is done. A deficiency found a year later is meaningless without a starting point, and many people arrive already deficient.
The dietitian and the psychologist
Two conversations that shape the years afterwards more than the surgical technique does. A pre-operative diet for two to three weeks shrinks the liver and makes the operation safer and quicker, and it is a requirement rather than a suggestion.
Surgery itself is laparoscopic, takes roughly one to two hours depending on which one, and involves four or five small incisions. Most people are walking the same evening, drinking the next morning and home within two or three days.
Brevity in that paragraph is deliberate, since the operation is the shortest and most predictable part of the whole undertaking. An hour, then years. Plan for the years.
The year that decides it
Follow-up sounds like the least interesting section on this page and it is the most important one, because the problems that follow these operations are silent.
You do not feel a vitamin D level falling. You do not feel your parathyroid glands compensating. By the time a deficiency announces itself through a fracture or through nerve damage, years of it have already passed. Silence is the problem. Blood work is the answer.
What a blood test at one year actually finds
Researchers measured parathyroid hormone about a year after surgery in 229 people who had undergone a sleeve gastrectomy or a gastric bypass, at an average of 483 days afterwards. Ninety of them, which is 39.3 percent, had a raised level, indicating secondary hyperparathyroidism, meaning the parathyroid glands were working overtime to hold calcium steady in the face of inadequate vitamin D and calcium. Alkaline phosphatase, a marker of bone turnover, was significantly higher in that group. The mean age of the whole group was 35, so these were young people. The authors concluded that routine biochemical monitoring and timely supplementation are essential to reduce long-term bone complications.
Two in five, at one year, with no symptoms.
That is the argument for follow-up stated more clearly than any brochure could state it, and it is the specific thing that a package holiday model of this surgery cannot deliver. Nobody feels a raised parathyroid hormone, in the way that nobody feels a slowly rising blood pressure or a falling iron level, and the whole category of harm this creates is defined by its silence. It is found by drawing blood on a schedule, or it is not found. There is no third option.
What good follow-up looks like is a written schedule, and never an invitation to get in touch. Bloods at three months, six months, twelve months, then annually for life, covering the same panel measured before surgery. A dietitian review at the points where eating changes, meaning the first weeks, the six month mark and the two year mark when appetite typically returns. A plan for weight regain before it happens and not after, since some regain is normal and the question is what is done about it. And an agreed route back to us if something goes wrong at two in the morning in another country. Write it down beforehand.
What can go wrong
These are safe operations in experienced hands, comparable to gallbladder removal in mortality terms, and that reassurance is worth having alongside the specifics and never in place of them. Both halves are true.
This table scrolls sideways on a narrow screen. Swipe or drag to see every column.
| Problem | When it happens, and what it means |
|---|---|
| Leak from a staple line or join | The serious early complication, usually within the first week. It is uncommon and it is treatable when recognised early, which is the whole argument for staying within reach of the unit through the first several days instead of flying home on day two and hoping. A fast pulse and breathlessness matter more than pain here. |
| Clots in the legs or lungs | Risk is raised by obesity, by surgery and by a long flight, which is an unfortunate combination. Injections continue after you are discharged, compression stockings are worn throughout, and walking begins on the same evening as the operation rather than the following morning. Timing the flight home is part of the medical plan and not a travel decision. |
| Reflux after a sleeve | Common enough to be a main reason for choosing differently, and it can appear in people who never had it. Most of it is managed with acid-suppressing medication taken daily, which many people are content with and some are not, and that preference belongs in the conversation before the operation is chosen. A minority need conversion to a bypass, which is why pre-operative endoscopy earns its place. |
| Internal hernia after a bypass | Occurs years later, often after substantial weight loss, and presents as intermittent severe abdominal pain. It is a surgical emergency and it is frequently missed by doctors unfamiliar with the anatomy, so carrying your operative note is not a formality. |
| Deficiencies and bone loss | Iron, vitamin B12, vitamin D, calcium and thiamine, all developing quietly over months to years without producing a single symptom you would think to mention to anybody. Iron deficiency reached 20 percent at one year after one type of bypass in a direct comparison. This is the category that follow-up exists to catch. |
Recovery and the first months
Hospital stay is two to three days.
Return to desk work takes two to three weeks and to physical work four to six. The diet advances in stages, from liquids for the first two weeks through puréed food to soft food and then to normal textures at around six to eight weeks, and the reason for the staging is mechanical and not nutritional. Your stomach holds a cupful. Textures come back slowly.
Several things surprise people and are worth expecting. Hunger often disappears entirely for some months, and its return at around eighteen months to two years is normal physiology and no sign that anything has gone wrong or that you have failed at something. Hair thinning at three to six months is common, relates to the speed of the weight loss and to protein intake, with nothing having gone wrong, and recovers on its own without treatment. Loose skin becomes noticeable at six to twelve months, and it is a separate matter with its own decisions attached, best considered once weight has been stable for a year, and not in the middle of losing it. Alcohol is absorbed differently after a bypass, so its effects arrive faster and harder than they used to, which is a genuine safety issue around driving and around dependency, and no mere curiosity. Two medical points belong in the first months, before anybody discovers them the hard way. Diabetes and blood pressure medication usually need reducing within days, which is why the written plan for that leaves with you. And pregnancy should be avoided for twelve to eighteen months, since rapid weight loss and nutritional shortfall are a poor environment for a pregnancy, while fertility often improves markedly and unexpectedly after surgery, so contraception is discussed with everybody for whom it is relevant. Fertility often returns fast.
Coming to Istanbul
How long you need to stay in Istanbul is ten to fourteen days, hotel nights included, and the length is set by the leak risk and not by how you feel. The first three or four days go on assessment, meaning endoscopy, bloods, the dietitian and psychologist appointments, anaesthetic review and a sleep study where indicated. Surgery follows, then two to three nights in hospital, then several more days nearby before flying. The wait is the point.
That last part is where we differ from a short package and it is a deliberate choice, and no upsell. A leak declares itself most often between day three and day seven, and a patient who is still in Istanbul when it happens is treated within hours, while a patient who flew home on day two arrives at an emergency department where nobody knows what operation was performed. We would rather you were bored in a hotel than convenient and far away. Flying is cleared once you are eating and drinking adequately, the wounds are dry and the anticoagulant plan is arranged for the journey. Clot risk after this combination of obesity, abdominal surgery and a long flight is the reason injections continue at home, stockings are worn and you walk the cabin. Interpreting is arranged in advance in English, Arabic, Russian, French and German. You go home with the operative note naming the exact procedure and the sizes used, your baseline and discharge bloods, a written supplement prescription, the medication reduction plan and a dated follow-up schedule. Check every line before you leave.
What moves the cost
This field is quoted more aggressively than any other in medical travel, and headline figures are usually built by removing the parts of the care that are hardest to see.
What actually moves the figure is clinical.
- Which operation is performed, since a bypass takes longer and uses more staple loads than a sleeve.
- Whether this is a first operation or a revision, which is technically harder, longer and carries a higher complication rate.
- Your starting weight and body shape, which change operating time, the equipment required and sometimes the theatre table itself.
- Whether sleep apnoea needs investigating and treating before surgery, and whether a machine is required overnight afterwards.
- How much of the assessment is done here rather than already completed at home to an acceptable standard.
- Whether other conditions need optimising first, meaning diabetes control, anaemia or liver disease.
- Whether a hiatus hernia is repaired at the same time, which is common and adds to the operation.
- How long the follow-up arrangement runs, and whether the supplements and blood tests are inside it or outside it.
Ask any written quotation five questions, and the last one is the one that separates units. Does it name the specific operation. Does it include the endoscopy and the full baseline blood panel. Does it cover a return to theatre and the intensive care nights if a leak occurs. Does it include the dietitian and psychologist appointments. And for how long afterwards does somebody remain responsible for your blood results, in writing, with dates. A quotation that answers those five describes a course of treatment. One that answers only the first describes an operation. Ask all five.
Follow-up once you are home
Blood tests are needed at three, six and twelve months, then annually for the rest of your life, covering vitamin D, B12, ferritin, folate, calcium, parathyroid hormone, full blood count, liver function and HbA1c.
Supplements are taken indefinitely, and which ones depend on the operation you had, which is why a prescription naming the actual preparations and doses is worth more than a leaflet listing categories. Any doctor can order these tests and any pharmacy can supply the supplements, so the arrangement is practical wherever you live, provided somebody has written down what to order and when. Any doctor can run them, and any pharmacy can supply what is on the prescription, so the arrangement works wherever you happen to live.
Five documents make that work, and you should leave with all of them.
- The operative note naming the exact procedure, the limb lengths or bougie size used, and any hiatus hernia repair performed.
- Your baseline blood panel from before surgery alongside the discharge panel, so later results can be compared against a starting point.
- A written supplement prescription with doses, naming the preparations rather than the categories.
- The medication reduction plan for diabetes and blood pressure drugs, with the thresholds at which each is changed.
- A dated follow-up schedule naming which tests at which intervals, and who to contact when something is abnormal.
Our team stays reachable for you and for your own doctor afterwards, and where a result comes back abnormal two years from now we would rather interpret it against what we actually did than have it guessed at. Send it over.
Frequently asked questions about metabolic surgery
Should I try the new weight loss injections instead?
Which operation gives the most weight loss?
Why do I need blood tests forever?
Will my diabetes go away?
I have reflux. Does that change things?
What is the difference between the two kinds of bypass?
Why can I not fly home after two days?
What happens if I regain weight?
Written by the Biruni Hospital medical editorial team.
Reviewed by Dr Yunus Emre Yavuz, Obesity and Metabolic Surgery.
References
- Pazos FPG, Gordilho RMV, Novelli EO, et al. Roux-en-Y gastric bypass versus sleeve gastrectomy for cardiometabolic outcomes, a systematic review and meta-analysis of randomized controlled trials. Obesity Surgery. 2026;36(6):3247-3258.
- Shamnad FR, Restrepo-Rodas G, Andrade LAM, et al. Secondary hyperparathyroidism in post-bariatric population, a descriptive analysis. Obesity Surgery. 2026;36(4):1747-1756.
- Thapa B, Schmittdiel JA, Arterburn D, et al. Clinical and demographic characteristics associated with diabetes remission in six integrated health care systems, a retrospective cohort study. Diabetes Care. 2025;48(10):1737-1743.
- Wolff Sagy Y, Winter EE, Abu Ahmad W, et al. Long-term health care utilization of GLP-1RA use versus bariatric metabolic surgery. JAMA Network Open. 2026;9(7):e2621305.
- Chenevas-Paule Q, Vivard J, Gignoux B, et al. Omega gastric bypass versus long biliary limb Roux-en-Y gastric bypass, a retrospective analysis with 1- and 3-year follow-up. Surgical Endoscopy. 2026;40(7):5790-5800.
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