What is single loop gastric bypass surgery?
Single loop gastric bypass surgery or mini gastric bypass surgery (MGBP) alters the pathway of your food from the stomach to the small bowel.
During your surgery, Dr Ozmen will divide the stomach into two parts and form a new, narrow stomach pouch. As the new stomach is much smaller it holds less food. The larger part of your stomach remains in your body but is no longer in contact with the food you eat. However, it continues to produce digestive juices which assist in your body’s digestive process.
Dr Ozmen then uses a 2 metre loop of bowel and creates a new bypass point surgically attaching it to the lower part of the stomach pouch. This new pathway means that your food bypasses 2 metres of the small intestine going directly into the small bowel.
Single loop gastric bypass surgery is a restrictive and malabsorptive procedure.

How does single loop gastric bypass surgery assist in weight loss?
Single loop gastric bypass surgery is a restrictive and malabsorptive procedure. This results in you losing weight in a number of ways.
Firstly, the reduced size of the new stomach limits the amount of food you are able to eat and while you are eating gives a feeling of fullness sooner. The other factors causing weight loss occurs due to the food’s new pathway which bypasses some of the small intestine and reduces the amount of calories and fat your body is able to absorb and the surgery causes changes in hormone levels that cause your appetite for food to be suppressed.
How much weight is generally lost with single loop gastric bypass surgery?
Studies have shown that expected weight loss from single loop gastric bypass surgery is similar to that of Roux-en-Y gastric bypass (RYGB) surgery. Typically, this will mean an expected 30-40% of your excess weight within 6 months and up to an average 70% in 1 year, however, some patients will lose less than 70% and some more.
After your body adjusts over time, long term excess weight loss reduction is estimated at approximately 50 – 60%.
What are the other health benefits (other than weight loss)?
Evidence shows that weight loss surgery provides patients with mental health as well as physical health benefits. For obese patients, these benefits includes remission of type 2 diabetes, prevention of coronary conditions, prevention of stroke, reversal of sleep apnoea, improved fertility and improved joint health.
What are the benefits of single loop gastric bypass surgery compared to other bariatric surgery options?
Studies have shown that single loop gastric bypass surgery provides similar weight loss results and overall health improvements to that of the more complex procedure of Roux-en-Y gastric bypass (RYGB).
The surgery is less technically complex, and has less potential for herniation of the bowel.
The single loop technique allows for a quicker operation and is also reversible or able to be revised to a Roux-en-Y gastric bypass procedure.
What are the risks and potential complications of single loop gastric bypass surgery?
There are general surgical risks associated with Single loop gastric bypass surgery is a comparatively new procedure and therefore there is as yet no long term data available and less research when compared to Roux-en-Y gastric bypass.
Due to the lower complexity of this surgery, there are generally less risks and complications associated with single loop gastric bypass surgery, however, some of the potential risks particularly related to this surgery include:
- The new pathway created allows for bile reflux. Persistent bile reflux may result in ulceration which could potentially have a long term risk of stomach or oesophageal cancer. However, patients who are experiencing ongoing reflux symptoms would be able to have the procedure reversed or revised to a standard RYGB.
- Due to the bypass of a large portion of the small intestine, your body needs ongoing vitamin and mineral supplements to counteract nutritional deficiencies following your surgery.
What is the cost of single loop gastric bypass surgery?
Single loop gastric bypass surgery is an elective procedure that is currently performed mainly in private hospitals. A portion of the cost of surgery will be covered by some private health insurance policies and you may also be eligible to access your Superannuation funds due to the overall resultant health benefits from weight loss surgery.
Please call our Sydney GI Surgery team to discuss your needs and for an accurate assessment of the cost involved.
Preparing for weight loss surgery
As with all surgical weight loss procedures, Dr Ozmen will commence you on a 2-3 week low calorie pre-operative diet. The purpose of the diet is to shrink your liver prior to your surgery to promote better keyhole access and ensure that your surgery is safer.
Recovery
There is a faster recovery time from single loop gastric bypass surgery due to the shorter operation time and as Dr Ozmen performs all bariatric surgery laparoscopically (by keyhole) your recovery time is further minimised. All patients recover differently and Dr Ozmen will discuss your specific risks with you prior to your surgery, however in general, recovery for single loop bypass surgery will usually require between 1-2 days in hospital before returning home. Normal activities can usually be resumed after 2 weeks, with full recovery anticipated in 4 weeks. After your surgery you will be required to adopt a strict diet consisting of clear liquid and smooth foods in the first 6 weeks following surgery. The food will gradually increase in consistency with the introduction of more solid foods. Once you have fully recovered from your surgery, you will be able to eat most food types (although in smaller quantities).
Life after single loop bypass surgery
The faster operation time and lower complexity of this procedure together with the achieved weight loss and improved quality of life following surgery is seeing single loop gastric bypass surgery becoming a more common option for surgical weight loss. The procedure has the additional advantage of having lower risks and being able to be reversed or revised. As the surgery is a malabsorptive procedure, you will need to include daily vitamin and mineral supplements to your diet to maintain good health.
Dr Ozmen advises that all bariatric surgery procedures including gastric bypass should be used as tool for weight loss. Success in achieving and maintaining your weight loss goals will need your ongoing commitment to changes in lifestyle that include a healthy, balanced diet and regular exercise. Without ongoing lifestyle changes, the regain of weight is common after any weight loss surgery.
As part of helping to ensure you realise your weight loss outcomes, Dr Ozmen will provide access to dieticians who specialise in weight loss surgery after care to assist you in adopting a healthy and sustainable eating plan.
