Gastric Bypass Surgery

Roux-en Y gastric bypass (RNYGB) is considered the “gold standard” weight control operation. It combines restriction with malabsorption which results in durable and significant weight loss. The Adelaide Bariatric Centre is one of the few clinics in Adelaide that offer the gastric bypass as a laparoscopic or keyhole procedure (not "minilap" which is another term for open or a large incision). Keyhole procedures results in a superior recovery compared with a traditional open or minilap operation. 

The gastric bypass has regained popularity in Australia

1. It is the most common laparoscopic bariatric operation performed in the USA. This was because gastric banding was only approved in the USA after 2001.
2. It results in significant and sustainable weight loss. Median weight loss at 12 months is 60 to 70% excess weight. Approximately 50% excess weight loss is maintained after 15 years.
3. It is particularly effective in the treatment of obesity related diseases especially type 2 diabetes.
4. The operation can be done with an acceptable mortality (0.3%) in a high risk group. Quality of life is good with minimal gastrointestinal side-effects. Macronutrient malabsorption does not occur however micronutrient malabsorption such as B12, calcium and iron are predictable problems that are easy to treat with supplementation.
5. It is often the preferred option for revisional weight loss surgery ie patients who have had a gastric band or gastric sleeve but have re-gained their weight and are considering further bariatric options. Surgeons at Adelaide Bariatric Centre have experience in converting gastric bands and sleeve gastrectomies to gastric bypass as a laparoscopic or keyhole procedure.

The operation is truly a bypass of the stomach. The stomach is bypassed so that food eaten goes into a small gastric pouch and then into a loop of small bowel (the jejunum).

THE GASTRIC BYPASS

How does it work?

Weight loss is achieved through the following mechanisms:

1. Early satiety is induced by the small gastric pouch.
2. Patients become intolerant to sweets as the rapid presence of sugar in the small bowel leads to unpleasant symptoms called “dumping”. Hence there is a tendency to avoid sweet and fatty foods.
3. Most importantly the operation results in suppression of appetite. This is thought to occur due to the rapid entry of foods into the small bowel which evokes a hormonal effect that induces satiety. It is thought that a similar hormonal response is responsible for the 75% cure rate of type II diabetes following gastric bypass.

What is achieved from the operation?

First and foremost the operation achieves weight loss. Significant weight loss will then have an effect on the physical and psychological consequences of obesity. These effects however are not as predictable as the weight loss.

For most patients gastric bypass will result in the loss of 50-70% of excess weight which means you will still be a little overweight but will have lost enough weight to reduce your obesity related risk profile to that approximating the normal population.

An operation that would reliably get the average patient to their ideal body weight would cause many people to lose too much weight and also result in severe nutritional deficiencies. To date gastric bypass is the only operation to be shown to reduce mortality from obesity. Approximately a 75% cure rate can be expected for most obesity related co morbidities such as Type II diabetes mellitus, elevated blood pressure, sleep apnoea, lipid abnormalities, and joint pain etc.

The operation allows the average patient to lose 75% of their excess weight in 12-18 months. After this most patients re-gain some weight. This weight gain occurs for a variety of reasons such as poor compliance with diet and exercise and physiological adaptation of the body to the operation. At 5, 10 and 15 years the weight loss stabilizes at approximately 50% of excess weight. Adaptation and maintenance of good eating and exercise habits are critical in limiting any weight regain.

Choosing to have a gastric bypass is a complex decision that should involve your surgeon. Your individual dietary habits and associated medical conditions may also influence this choice. Patients who are “sweet-eaters” may have more success with a gastric bypass than a purely restrictive procedure because of the possibility of dumping.

What is life like with a gastric bypass?

You will be less hungry and also feel satisfied after eating small meals. The amount of food you eat is approximately 25% of your previous meal. When going to a restaurant you can eat an entrée sized meal and feel satisfied. The key point being that a small meal satisfies you hence the experience is different to dieting and therefore sustainable in the long term.

Sweet and fatty foods are poorly tolerated and best avoided. These foods will cause “dumping” due to the rapid presence of high osmolality fluid in the small bowel. Symptoms are nausea, dizziness, palpitations, sweating and abdominal discomfort. To avoid dumping, high sugar and fat content foods should be avoided and food should be eaten dry and not mixed with fluids. This of course assists with weight loss.

Apart from a commitment to “healthy eating” no other foods are specifically banned.

Multivitamins and calcium supplementation must be taken by all. Vitamin B12 injection is needed third monthly. Iron supplements may be needed pending biochemical results. These requirements are life long and critical to good health.

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