Gastric Bypass
Roux-en-Y Gastric Bypass

During this surgery, the surgeon creates a pouch similar in size to an egg, therefore restricting the volume that can be eaten.
This pouch is detached from the main part of the stomach. The lower part of the small bowel is then cut, moved up to and attached to the pouch.
The bowel that has been bypassed is then attached to the small bowel, thereby allowing the digestive juices from the pancreas to be mixed with the food coming from the small pouch.
One Anastamosis Gastric Bypass

This can also be referred to as the Mini Gastric Bypass (MGB).
A small elongated stomach pouch is created. This pouch is detached from the main part of the stomach. A loop of small bowel is then lifted up and connected to the pouch allowing the digestive juices from the pancreas to be mixed with the food coming from the small pouch.
The bypass works in two ways
- It restricts the amount that can be eaten and the by-passing of some of the small bowel means that there is a reduction in the amount of calories, protein, vitamins and minerals absorbed.
- To try to prevent vitamin and mineral deficiencies, you will be required to take a daily vitamin and mineral supplement for life.
What are the Benefits and Drawbacks of having a Bypass?
Benefits:
- You can expect to lose 60 – 70% of your excess body weight after 2 years.
- Average initial weight loss is quick.
- Evidence suggests that gut hormones can be altered which affects appetite.
- Has a high-resolution rate of diabetes (75%).
Drawbacks:
- Has a higher mortality rate (1;250 chance) and more serious complications than other operations.
- It will be necessary to take multivitamin and minerals for life. You may need to take extra supplements based on your dietary intake and blood tests.
- ‘Dumping syndrome’ can occur after eating foods with too much sugar or fat, with symptoms including nausea sweating, faintness, vomiting, and potentially diarrhea.
- It is effectively irreversible. For example, if it were deemed a medical emergency, if could be reversed.
- Medication needs to be reviewed to ensure adequate absorption.
- Increased risk of reflux can occur with OAGB.
- You may not lose or maintain weight loss if you do not stick to healthy eating and lifestyle guidelines.
- It is recommended you avoid alcohol for 1 year after surgery. It may be limited after this, as the side effects of alcohol can occur more rapidly after the bypass, and it contributes to calorie intake and potentially less inhibition with food choices.
Please note: Lifelong vitamin and mineral supplements are expected with both the Gastric Bypasses and the Sleeve Gastrectomy, and you will need regular bloods tests to monitor your nutritional status.
Sleeve Gastrectomy

During this surgery, the surgeon removes ¾ of your stomach, leaving a small narrow tube.
It works by reducing your stomach size and therefore restriction the amount of food that can be eaten.
It can also affect the hormones which regulate your appetite, making you feel less hungry.
What are the benefits and drawbacks of having a Sleeve Gastrectomy?
Benefits:
- You can expect to lose 50 – 60% of your excess body weight after 2 years.
- It can be converted to a full bypass if needed
- Evidence suggests that gut hormones can be altered which affects appetite.
- Compared to the bypass, less likely to suffer nutritional deficiencies unless the diet is unbalanced. However, with such a relatively new procedure, please note this may change as new evidence is collected.
Drawbacks:
- It is a relatively new procedure as a ‘standalone’ treatment, so longer term data is not yet available.
- It is non-reversible as 75% of the stomach is removed from your body.
- You may not lose or maintain weight loss if you do not stick to healthy eating and lifestyle guidelines.
- Its effects on appetite may only be temporary
- It is recommended you avoid alcohol for 1 year after surgery. After 1 year, if you decide to start drinking alcohol, please limit.
Patients undergoing a Sleeve Gastrectomy or One Anastamosis Gastric Bypass will require a pre-operative endoscopy to rule out Gastric Reflux disease.