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Weight loss surgery

One Anastomosis Gastric Bypass
(Mini Bypass)

The OAGB is also known as the ‘single loop bypass’ and the mini-bypass. It is a minimally invasive procedure performed with a laparoscopic technique.

There are basically two main steps to this operation:

  1. The surgeon creates a small tube-like stomach pouch which is detached from the rest of the stomach.
  2. This gastric pouch is then connected up to the intestine, bypassing up to 200cm of the total length of the small bowel.

This technique differs from the Roux-en-Y gastric bypass, which has an extra join between the small bowel.

The OAGB typically results in 30 to 40% weight loss or up to 80% excess weight loss over a period of about 18 months. The most rapid weight loss is usually in the first 6 months. This weight loss is achieved through both the restrictive effect of the small pouch and the metabolic effect of bypassing the small intestine.

The OAGB has a good complication profile with a low  complication rate of around 5%. A small proportion of those patients may require revisional surgery for bile reflux or malnutrition. A significant advantage is that the OAGB does result in a lower incidence of small bowel obstruction from internal hernia formation.

  • Technically easier to perform and a shorter operating time than the RYGB
  • Considered reversible
  • Significant weight loss
  • Maintain good quality of eating
  • Lower risk of internal hernia
  • Risk of stomach ulcer
  • Risk of micronutrient deficiencies
  • Risk of dumping syndrome
  • Risk of bile reflux
Request an appointment for more information.

Dr Benedict Mackay’s approach is designed not only to perform your surgery but equip you with the tools and information to achieve sustained, long term weight loss.

One of Australia’s most highly trained and qualified bariatric surgeons, Dr Benedict Mackay combines impressive experience with a deep knowledge of modern surgical techniques and a commitment to achieving the very best outcome for patients.

Dr Benedict Mackay
BSc, MBChB, MRCS (England), FRACS
General, Upper GI and Bariatric Surgeon

Professional Associations

Benefits of weight loss surgery.

Weight loss surgery works by increasing your sense of fullness after eating. Reference: 1,2

Expected weight loss in one year is about 20 – 33% of your overall body weight.Reference: 3

People having keyhole surgery have a shorter time in hospital, fewer complications and less time to make a full recovery.Reference: 4,5

An overall Improvement to your quality of life.

Bariatric surgery has been linked to improvements in type 2 diabetes, reduced blood sugar, reduced use of medications, and even resolution of the condition.


Supporting you on your weight loss journey.

If you have any questions, please get in touch.