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Roux-en-Y Gastric Bypass (LRYGB)

Eating after Gastric BypassEating after Gastric Bypass

Pre-op diet Food basedYour Liver Shrinkage diet prior to surgery (Diet Option)

Eating after Gastric BandSlimfast Liver Shrinkage Diet

Roux-en-Y Gastric Bypass (LRYGB)In this procedure, the surgeon creates a small gastric pouch in the same position and the pouch is the same size as that seen with the gastric band. On this occasion though, the stomach is cut through so that the pouch is no longer attached to the rest of the stomach. The small bowel is then divided 50-80cm (20-30 inches) from its top and the cut end brought up to and attached to the gastric pouch. In this way, food enters the pouch, bypasses the initial part of the small bowel (duodenum) and enters further down than normal (into the Jejunum). The divided end of the bowel is re-attached 80 – 100 cm (30-40 inches) below where the other end is joined to the gastric pouch. This ensures that the food does not stimulate the secretion of certain hormones and the gastric and pancreatic juices required to digest the food properly enter the small bowel further downstream.

As with the gastric band the main effect will be that you will generally be able to eat small amounts only but there is no significant reduction in the amount of calories and protein you can absorb, even though most of your stomach and upper part of the small bowel is bypassed. However, there is a 30% chance that you may develop vitamin and mineral deficiency unless you take daily supplements - you will therefore daily need to take tablets containing iron, calcium and certain vitamins, as well as, have 3-monthly vitamin B12 injections.


  • Helps improve health problems as shown in table 1 and 2 (Page 6 and 7)
  • The average excess weight loss after a gastric bypass procedure is generally higher than a purely restrictive procedure e.g. gastric band
  • You can expect to lose roughly 70 – 80 % of your excess weight after two years - it is unusual for a patient not to lose the expected amount of weight
  • Weight loss starts from the time of surgery
  • Studies show the large amount of weight loss helps to improve qualify of life


  • It will be necessary to take regular iron, calcium multivitamin and B12 supplements
  • A condition known as dumping syndrome can occur from eating too much sugar or large amounts of food. While it isn’t considered a serious health risk, the results can be very unpleasant. Symptoms can include vomiting, nausea, weakness, sweating, faintness, and, on occasion, diarrhoea. Some patients are unable to eat sugary foods after surgery
  • Whilst it is possible to reverse the procedure, it is technically very demanding
  • You may develop internal hernias

Health improvements after banding vs. bypass

Health Problem Gastric band Gastric bypass
Cured of diabetes (Off all medication) 48% 84%
Diabetes improved 80% 93%
High cholesterol improved 78% 95%
High blood pressure (Off all medication) 43% 68%
High blood pressure- improved 70% 87%
Sleep Apnoea- improved 68% 94%

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