One Anastomosis Gastric Bypass

One Anastomosis Gastric Bypass

The laparoscopic one anastomosis gastric bypass is a variant of the Laparoscopic Roux en Y gastric bypass. It is also known as the mini gastric bypass (MGB) or omega loop gastric bypass. It is significantly increasing worldwide in terms of popularity because of it's excellent results. It has excellent short and long term weight loss.

The operation involves the formation of a long narrow gastric pouch (40ml size). The stomach pouch then is joined to the small bowel so that 1.5 to 2m of the small bowel is bypassed. As there is no second anastomosis there are fewer complications. At one year the average excess body weight loss is 75%.

As this operation has more "power" in terms of weight loss compared to the sleeve gastrectomy, it is a good choice for people with BMIs above 50.


  • Weight loss is as good, if not better than the Roux en Y gastric bypass
  • Has a lower rate of complications than Roux en Y gastric bypass
  • Has inbuilt "dumping syndrome" that reinforces healthy eating, as the bad foods i.e. fat and sugar cause diarrhoea and pain
  • Good quality of eating healthy foods
  • Excellent at resolving or markedly improving Type 2 Diabetes even before the patient is discharged from hospital the second day after surgery


  • Like the other operations, life long vitamin and mineral supplementation is required
  • A small number of patients can have diarrhoea after surgery
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