Gastric bypass is a bariatric operation in which a small pouch is created from the upper stomach and part of the small intestine is bypassed. It works both by restricting intake and by reducing absorption. Because its metabolic effect is stronger than that of sleeve gastrectomy, it comes to the fore in patients with type 2 diabetes and significant reflux. On average 65-75 per cent of excess weight is lost, and lifelong vitamin supplementation is required.
Sleeve gastrectomy may be the first procedure that comes to mind in bariatric surgery, but it is not the best option for every patient. Gastric bypass has a stronger metabolic effect and comes to the fore particularly in patients with type 2 diabetes and significant reflux. This article gathers the questions most often asked about it by patients researching bariatric surgery in Mersin.
How Is Gastric Bypass Performed?
The operation has two stages. First a small gastric pouch of roughly 30 millilitres is created from the upper stomach; the rest of the stomach is not removed but is left in place, outside the path of food. The small intestine is then divided at a set point and joined directly to this pouch, so that food bypasses most of the stomach and the duodenum.
The operation is performed laparoscopically, through a few millimetre-sized openings in the abdominal wall, and usually takes 2 to 2.5 hours.
How Does It Differ from Sleeve Gastrectomy?
Sleeve gastrectomy works through restriction and a hormonal effect alone. Gastric bypass adds reduced absorption: because food bypasses part of the small intestine, fewer calories and nutrients are absorbed.
This has two consequences. First, the metabolic effect is stronger; in most patients blood glucose begins to improve within days of surgery, before any weight is lost. Second, the risk of vitamin and mineral deficiency is higher, so the supplement regimen is more extensive than after sleeve gastrectomy.
Another decisive difference is reflux. Reflux symptoms can increase after sleeve gastrectomy, whereas gastric bypass generally improves them. That is the main reason it is preferred in patients with significant reflux.
Who Is It For?
- A body mass index of 40 or above
- A BMI between 35 and 40 with an associated condition such as type 2 diabetes
- Significant reflux and hiatal hernia
- Patients who have had a sleeve gastrectomy and lost too little weight or developed reflux
- Patients whose eating pattern is heavily weighted towards sweet foods
Dumping Syndrome
This is specific to gastric bypass. Sugary and fatty foods passing rapidly into the small intestine cause palpitations, sweating, nausea, abdominal cramps and weakness. It is uncomfortable but not dangerous, and it in fact acts as a form of feedback that steers the patient away from sugary food. Portion control, avoiding sugar and taking fluids between meals largely prevent it.
The Vitamin Regimen
Supplements after gastric bypass are lifelong and cannot be skipped:
- Vitamin B12: absorption falls markedly because the duodenum is bypassed
- Iron: close monitoring is needed, particularly in menstruating women
- Calcium and vitamin D: for bone health
- Folic acid and zinc
Blood tests are recommended at 1, 3, 6 and 12 months in the first year, then annually. This follow-up is part of the operation, not an optional extra afterwards.
Which Procedure for Whom?
In patients without reflux and with a limited burden of associated conditions, sleeve gastrectomy generally comes first. Gastric bypass is considered in patients with type 2 diabetes, significant reflux, or an earlier sleeve gastrectomy that did not achieve enough. The decision weighs BMI, associated conditions, eating habits and the patient's capacity to keep to follow-up.
Choosing the Right Bariatric Procedure
Over his career Op. Dr. Ersan Semerci has performed more than 3,000 sleeve gastrectomy and bariatric surgery cases. Gastric bypass, sleeve gastrectomy, mini gastric bypass and transit bipartition are all among the procedures he performs.
He has kept his training in this field up to date: the Gastric Bypass and Beyond Core Training Course (2nd Bariatric and Metabolic Surgery Congress, 2017), the Laparoscopic Bariatric Surgery Course (Acıbadem University, 2015) and bariatric re-do surgery training completed in Bruges under Medtronic Medical Education (2023 and June 2025).
Op. Dr. Ersan Semerci has practised in Mersin since 2010 and currently works at Medicalpark Mersin Hospital. Consultations and operations are carried out at this hospital.
Op. Dr. Ersan Semerci has practised in Mersin since 2010 and currently works at Medicalpark Mersin Hospital. Consultations and operations in Gastric Bypass are carried out at this hospital. Patients travelling from Mersin and neighbouring provinces can book via WhatsApp.
Book on WhatsAppCan a gastric bypass be reversed?
It is technically reversible because the stomach is not removed. However, that is a separate and demanding operation, rarely needed, and it should not be regarded as a routine option.
Which produces more weight loss, sleeve gastrectomy or gastric bypass?
Average excess weight loss is somewhat higher with gastric bypass (65-75 per cent against 60-70 per cent). The difference, however, matters less than the patient's diet and adherence to follow-up.
How will my medication be affected?
Because absorption changes, the dose and form of some medicines may need adjusting. Patients on long-term medication should discuss this with their doctor before surgery.
Is there a risk of ulcer?
An ulcer can develop where the stomach joins the intestine. Smoking, non-steroidal anti-inflammatory painkillers and alcohol raise that risk markedly, which is why stopping smoking matters particularly here.
I am travelling from Adana or Antalya. How does the process work?
You can send any investigations you already have via WhatsApp beforehand. The first consultation and any missing tests are completed in Mersin; consultation, surgery and checks all take place at Medicalpark Mersin Hospital. Follow-up once you are home continues via WhatsApp.
Insufficient weight loss, weight regain and reflux after sleeve gastrectomy: how the decision to revise is made, which options exist and how the process runs.
Answers to the most common questions about appointments, the hospital, treatment scope and surgical experience are in the FAQ section on the home page.
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For Obesity and related symptoms you can book an appointment at Medicalpark Mersin Hospital. Mezitli / Mersin, Turkey, weekdays 09:00-17:00.
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