Gastric Bypass


A Gastric Bypass creates a small stomach pouch, with a content of approximately 75CC, using surgical staples. This anterior stomach is closed up entirely and separated from the rest of the stomach, resulting in a small stomach pouch. This will stop you from eating large amounts and make you feel full quicker (restriction). A thin intestinal limb (or alimentary limb) measuring 150 cm is then connected to the stomach pouch, so food from the oesophagus enters the small intestine directly, via the stomach pouch. Only 150 cm lower, the small intestine, where the gastric juices can be found (biliary limb) is connected to this intestinal limb. Since food is only digested when in contact with these gastric juices, less time is left for digestion and absorption, hence not all calories you take in are in fact being absorbed by the body. This is called malabsorption.    

For whom

A Gastric Bypass is considered the gold standard of all weight loss surgeries and in most cases turns out to be the best solution.

This surgery is preferred for patients with a mixed diet, eating too much and mainly unhealthy food (fatty food, sweets).

Since gastric bypass surgery can lead to significant improvement in diabetes or even stop the condition, it is regarded as the best procedure for obesity patients with diabetes. 80% of diabetes patients will no longer need any diabetes medication, shortly after having undergone the procedure. 


  • Good to excellent long-term results  
  • This is a laparoscopic procedure, with less discomfort post-surgery and a significant lower risk of incisional hernia  
  • Safe procedure with relatively little risk of complications 
  • Retaining quality of life (when a couple of guidelines are being adhered to)  
  • Contrary to a gastric band, no material foreign to the body is used, lowering the risk of infection  
  • A Gastric Bypass is reversible 


A Gastric Bypass is a safe procedure, with little risk of complications.

Possible complications/discomfort: 

  • Leakage (0.1 %): the stomach as well as the small intestine is cut open, with the edges stapled together to close up. The staples can come loose resulting in leakage.
  • Dumping syndrome (7-15 %): with food reaching the small intestine very fast, carbohydrates and fats can cause a reaction known as ‘dumping syndrome’. Patients can experience sweating, cramps in the abdomen, a raised pulse and drop in blood pressure. These symptoms do pass quickly and in fact help to prevent you eating highly calorific food.
  • Lactose intolerance: some patients might develop lactose intolerance post-surgery. Symptoms can be avoided by replacing any products based on milk by soy and lactose free products (Dilea). 
  • Ulcers (3 %): an ulcer could develop within the stomach-small intestine anastomosis area. This may cause pains in the upper abdomen, caused by several factors. These ulcers can be hard to cure and will mostly be treated with gastric acid suppressants. In general, patients are also advised to stop smoking.
  • Vitamin deficiencies can occur because part of the small intestine is bridged, increasing the risk of developing deficiencies in for instance iron, folic acid, vitamin B12, zinc, phosphorus, vitamin A and D. Strict check-ups by your doctor are highly advisable, including regular blood exams.
  • Hair loss: almost 1 in 2 patients will experience hair loss to a certain extent. Complete baldness will not occur and the hair loss is only temporarily. 

Hospitalisation and after care  

  • Standard hospitalisation is 3 nights.
  • You can start taking liquids the day after the surgery
  • On the second day after surgery an X-ray will be taken to ensure there are no leakages. Once cleared, you can start taking liquidised food
  • A physiotherapist will see you daily to practice breathing exercises
  • Before being discharged, a dietician will take you through the dietary guidelines
  • Our psychologist will schedule a follow-up appointment
  • Once home, a home care nurse will see you for 8 days for phlebitis injections
  • Special dressings will cover the small surgery incisions, allowing you to take a shower. These dressings will be removed during the first check-up with your doctor.
  • In order to prevent small ulcers, a 3-month course of gastric acid suppressants will be prescribed
  • One month after surgery, you will start taking a poly-vitamin to prevent deficiencies. Extra vitamin D is also advisable.
  • After 2 weeks you will be able to start with the post-surgery fitness program
  • You will normally be entitled to 6 weeks of work incapacity
  • Regular doctor check-ups are necessary throughout the rest of your life. The first year, these consultations will take place every 4 months, the second year each 6 months and after that a yearly check-up should suffice. 

Your diet after a Gastric Bypass 

The first weeks after surgery are the most important when it comes to preventing and avoiding complications. For the first 3 weeks you will be on a strict liquid diet as to not put the staples under any pressure.

Afterwards you will slowly make the switch to solid food, first with pureed food. Portion size has to be kept small, to prevent the stomach and small intestine from expanding. This will require some discipline.

Dumping syndrome can occur when you eat food rich in carbohydrates and fat. These kind of foods should therefore be eliminated from your diet.

Some patients might develop lactose intolerance post-surgery, in which case milk based products should be replaced by soy-free or lactose-free products.

Since each meal you can only eat small quantities before feeling full, you might eat too little in the first months. This might cause low blood sugar levels (= hypoglycaemia), making you feel tired, sweaty and nauseous.

In order to take in a sufficient amount of calories and avoid instable blood sugar levels, we advise you to eat small quantities throughout the day, namely 3 main meals, and 3 snacks low in calories.

Do pay specific attention to your protein intake, since protein stops muscle tissue from deteriorating. We advise you to consume 80 grams of protein daily, from meat, fish, eggs and dairy products. We also recommend one protein shake par day or high-protein products. 


Since the Gastric Bypass combines restriction and malabsorption effects, this surgery normally results in drastic weight loss. When you stick to the guidelines, 75% of excess weight will be lost. Weight loss is highest in the first 6 months, and stabilises after 12 to 18 months.

Better results will be booked when you adhere to the rules: small portions, food low in calories and high in proteins, plenty of exercise.