Laparoscopic Gastric Bypass

Gastric Bypass

Also known as Bypass, Roux-en Y gastric Bypass

In summary

You want to eat less, and the stomach holds less food, and therefore eat less, and the body cannot absorb all the calories you eat.


Dr Draper does not perform Gastric Bypass surgery and this information is provided for educational purposes.


Major rearrangement of the GI tract so that fat and sugar are less well absorbed

The gastrointestinal tract absorbs nutrients starting in the small bowel (small intestine) essentially. The fats and sugars in our diets are the main source of calories. Fats and sugars are mostly absorbed in the earlier parts of the small bowel (proximal small intestine). The bypass operations rearrange the gastrointestinal tract so that the fats and sugars you eat are diverted away from the proximal small bowel and so are only poorly absorbed and therefore decrease your body’s calorie intake. The various bypass operations do this in differing ways.

The Roux-en Y Gastric Bypass (RYGB) is the classic form of this operation. In this form of the bypass the stomach is made very small by stapling off the majority of the stomach, which is then left in place but out of the “food circuit”. The small intestine is then stapled or sewn to the stomach so that food passes out from the small stomach into the bowel. The bowel is joined further down the way so that the secretions etc from the bypassed portion of bowel can be cleared away. In the end we have bypassed about 100cm to 150cm of small intestine and reconnected everything so that food passes all the way though: most things are absorbed properly, but calories are poorly absorbed. The way the bowel and stomach are arranged at the end looks something like a Y and is named after this and the French surgeon who invented it, Roux.

Eating fats and sugars causes dumping syndrome

Dumping Syndrome is perhaps best described as food being dumped in the wrong part of the gastrointestinal tract. Or the food being in the wrong place at the wrong time. It is a collection of symptoms and effects that are caused by the way the gastrointestinal tract has been rearranged combined with the way you eat.

The stomach and bowel push food along at a speed that optimises absorption of nutrition. After a bypass these very precise mechanisms are disrupted so that food goes along at the wrong speed, and usually a bit too fast, especially if certain foods are eaten. As the food leaves the stomach, it goes too fast and the pancreas and numerous other organs secrete the wrong amount of hormones at the wrong time. This is usually barely noticeable. But if you eat a large meal of just one food type, especially fat or sugar, the error the guts make is large. This will give you dumping syndrome. So eat small and mixed up meals with a little bit of food from all food groups and types, and you will avoid dumping syndrome.(See Bypass Eating Rules)

Dumping syndrome is caused by a number of mechanisms, and there a number of different dumping syndromes. The form of dumping syndrome that effects people with a RYGB for weight loss is usually due to eating habits. The eating habits that resolve the dumping syndrome also improve weight loss, so the eating rules are well worth following.

The symptoms of dumping syndrome are numerous and varied depending on which type is occurring. Basically, if you eat the wrong foods, you will experience a combination of diarrhoea, abdominal bloating, abdominal pain, sweatiness, a strong desire to lie down shortly after a meal, flatulence, malodorous flatulence, belching and many others. If you have had a bypass and experience these symptoms, then follow the eating rules and tell your surgical team, and hopefully they will resolve. However, some forms of dumping syndrome require revision surgery.

The upshot with dumping syndrome is that is you eat well dumping syndrome will usually resolve. It will discourage you from eating the wrong foods and so facilitate your weight loss.

Smaller stomach results in smaller meals

The volume of the stomach with gastric Bypass is very small. In some operations it is possible to make the stomach a precise size using a measuring device. But in other operations, particularly revision surgery, the volume is more approximate. The volume we are aiming for is around 150ml.

This means that the meals you eat must be very small and eaten very slowly.

Decreased hunger

The Gastric Bypass decreases hunger by a number of mechanisms, and most people have an overall decrease interest in food.

Often used for revision surgery

Gastric Bypass is the operation surgeons use for a wide range of problems in the gastrointestinal tract and has been around for many years. It is probably the Gold Standard operation for weight loss, although many surgeons would argue this point. (Gold Standard means it is the best operation, and that all other operations are compared to it.) The bypass is used when the patient must lose the greatest amount of weight, and for revision surgery. It is used in revision surgery because if you are having your second or third operation, you don’t really want to be facing further surgery at some time, and so you need to go for the best option. Also, in revision situations the Bypass is often the safest and most feasible operative choice. Revision surgery is required in 2 main situations;

Inadequate weight loss

Gastric Bypass achieves the greatest amount of weight loss on average and so is a good option in revision surgery if the indication for the revision surgery is poor weight loss. As a general rule, if you fail to lose enough weight with your first operation, for whatever reason, you really ought ot consider stepping up to the next level of surgery.

As an option for revision after Slipped Band

Gastric Bypass is one option after a slipped band, especially if there was poor weight loss before the band slipped.

Excess weight loss and malnutrition can sometimes occur

There are a number of nutrients which are poorly absorbed, in particular Vitamin D, but also B vitamins and Iron. So nutritional monitoring is important. And, if you don’t eat enough healthy food, excessive weight loss is possible.

Largest amount of weight loss

We should see about 80% excess weight loss after a gastric bypass. This is greater than any other operation commonly performed in Australia (exceptions include the Bilio-Pancreatic Diversion (BPD), Duodenal Switch (DS) and other operations).

Highest risk

Compared with gastric band surgery and Sleeve Gastrectomy the risks of gastric Bypass are the greatest at around 5% major complications and 1 in 200 death rate. It should therefore be undertaken with full understanding of why it is being chosen above the other options. The main risks are of leaks from the various suture lines and staple lines of which there are 6 in total. But also risks from infections etc

Malabsorption, dumping and malnutrition can occur

These are explained above.

Not adjustable or reversible

The Gastric Bypass cannot be reversed completely. But it can be modified if the weight loss is excessive or inadequate. The volume of the stomach can be made smaller, for example, if the meals remain too big and the stomach size is the cause. Certainly it cannot be adjusted without surgery. However, the amount of weight loss achieved can be improved by following the eating rules better in most cases.

Complex surgery

From the description and diagram it is clear Gastric Bypass is complex surgery. The more complexities in an operation, the more that can go wrong, or cause minor but wide reaching consequences. So this makes Gastric Bypass less appealing for many people. So choose the operation that is the safest and simplest operation that will help you achieve your weight loss goals. Gastric Bypass is simpler than BPD or DS and is therefore more popular in Australia than these other options.

Weight loss takes 6 to 24 months

As with all weight loss operations the weight loss usually takes 6 to 24 months.

Bypass Eating Rules

Chew well and eat slowly
Small meals
Avoid fats and sugars (dumping syndrome)
Nutrition dense foods (malabsorption)
The details of the eating rules will be explained to you by the surgeon and dietitian, and will be available on this website soon.

2 weeks off work
4 night stay in hospital

“I just need the operation with the biggest amount of weight loss”

Dr Draper does not perform Gastric Bypass surgery and this information is provided for educational purposes.

Any surgical or invasive procedure carries risks. Before proceeding, you should seek a second opinion from an appropriately qualified health practitioner.

Watch Live SurgeryDo I Qualify for Weight Loss Surgery?

Please Contact Melbourne Bariatrics on  03  9770  7189  for more information or to make an appointment
to Top