Dr. Bruno Dillemans

General & obesity surgeon

Gastric Bypass

The Roux-En-Y Gastric Bypass, is considered the "gold standard" of modern obesity surgery

The Roux-En-Y Gastric Bypassis a restrictive procedure combined with a modified gastric bypass that moderately limits calorie and nutrient absorption and may lead to altered food choices. The Roux-En-Y works by decreasing food intake, limiting the amount of food the stomach can hold by closing off a significant portion of the stomach and delaying the emptying of the stomach (gastric pouch).

This procedure is a combination of restriction and malabsorption and therefore has a two-way weight reducing effect.

How it works

Figure 1                                    Figure 2                             Figure 3               Figure 4


The first figure shows the esophagus, the stomach  and the small intestine.

The Roux-En-Y Gastric Bypass achieves its effects by creating a very small (around 1 ounce) stomach pouch from which the rest of the stomach is permanently divided and separated (figure 2). Below the staple line the stomach keeps obtained but no food will enter here. The stomach will still produce gastric juices and enzymes essential for digestion and absorption of nutrients.

The small intestine is cut about 18 inches below the stomach, and is arranged to provide an outlet to the small stomach, while maintaining the flow of digestive juices at the same time (figure 3). The lower part of the stomach is bypassed, and food enters the second part of the small bowel (figure 4). The operation works by reducing food intake, and reducing the feeling of hunger. The result is a very early sense of fullness, followed by a very profound sense of satisfaction. Even though the portion size may be small, there is no hunger, and no feeling of having been deprived. Most patients will experience "dumping syndrome" when they eat sweets. "Dumping syndrome" causes the patient to have crampy abdominal pain, feel faint and have diarrhea. A portion of the small bowel is bypassed causing malabsorption, which leads to more weight loss. Patients feel indifferent to even the choicest of foods.

The Gastric Bypass provides an excellent tool for gaining long-term control of weight, without the hunger or craving usually associated with small portions, or with dieting. Weight loss of 80 - 100% of excess body weight is achievable for most patients, and long-term maintenance of weight loss is very successful. It does, however, require adherence to a simple and straightforward behavioural plan.

The surgery takes approximately 50 minutes, with a 2 to 3 nights stay in hospital.

Six months and twelve months after surgery, and later on a yearly basis you need a good blood test monitored by your GP to control if do not develop any shortage in any important vitamin or mineral.

Over-eating and poor eating habits can still jeopardize your success and you are also likely to experience 'dumping syndrome' if you consume foods high in sugar or fat. The side effects include diarrhea, stomach cramps, sweating and dizziness.

Bypass clip from bruno dillemans on Vimeo.

Average weight loss

66-80% of excess weight within 2 years

Risks and complications

Like any surgical procedure there are possible risks and complications. These are rare and everything possible will be done to prevent them from happening. The most recognised and documented are:

  • Haemorrhage

  • Infection

  • Bowel perforation

  • Anaesthetic reactions

  • Anastomotic leak

  • Dumping Syndrome

  • Nausea and vomiting