Laparoscopic Gastric Bypass

First performed in 1967, still the gold standard, against which other operations are compared

LRYGB: Who is it for?

Because it forces dietary change on patients, gastric bypass is still the most reliable weight loss operation. It is also the most effective operation for patients with metabolic illnesses. A typical patient would be:

  • Higher BMIs; BMI >45 kg/m2
  • Older, with low basal metabolic rate
  • Inactive, sedentary, with low calorie expenditure
  • Suffering from severe metabolic illness: Poorly controlled T2DM, BP, cholesterol etc
  • Lacking dietary discipline and know they are unlikely to change
  • Sweet tooth: unable to not eat chocolate, sweets, ice-cream etc

LRYGB: The Procedure & Recovery

  • Laparoscopic (Keyhole) surgery: 5 or 6 small incisions
  • General Anaesthetic
  • Two night hospital stay
  • Two week recovery time
  • A small gastric pouch, 20ml in volume, is formed from the upper stomach
  • The first 2m of the small bowel, are re-configured into a 'Y' shape (Roux en-Y)
  • One arm of the 'Y', joins the small gastric pouch to the small bowel
  • Ingested food no longer enters the stomach or duodenum, which is bypassed.

LRYGB: Mechanism of Action

Reduced appetite and early fullness

  • Food bypassing the stomach causes a change in gut appetite controlling hormones
  • Patients become less hungry, sometimes disinterested in food
  • Patients feel full sooner

Reduced portion size

  • In the short term patients eat a few mouthfuls of food
  • In the longer-term, patients will eat a child sized portion


  • Dumping is a patient response to eating sugar or high fat containing foods
  • Anxiety, sweating, abdominal cramps, nausea, diarrhoea and overwhelming tiredness
  • Can be a useful deterrrent for patients, who find it hard not to eat sugar

LRYGB: Weight loss & impact on metabolic illness

LRYGB is the most reliable operation, for weight loss. It forces dietary change on patients


A person who is ten stone over their ideal weight, can expect to lose 7 to 8 stone and sometimes more. The weight loss will result in:

  • Remission or much better control of type 2 diabetes mellitus
  • Remission of gastro-oesophageal reflux
  • Improved blood pressure control
  • Remission of Obstructive Sleep apnoea
  • Improved mobility and a better quality of life

LRYGB: Diet and Lifestyle

LRYGB does restrict a patient's diet and lifestyle

  • More textured foods, such as red meat maybe difficult to eat
  • Foods that swell, such as pasta and rice, may be difficult to eat
  • Eating out, can sometimes be challenging, if the menu is restrictive
  • Sugar containing foods, cause dumping

​Alcohol is absorbed, much more rapidly

  • Patients become drunk very quickly
  • Alcohol dependency, can be an issue
  • This limits partying; patients can become very 'cheap dates'

Smoking is prohibited, because it can cause life-threatening ulcers

LRYGB: Maintenance and Aftercare

Two years aftercare is essential

  • For support, with the recommended diet, moving from pureed to solid foods
  • To learn how to eat with the bypass, to ensure the best long-term outcome
  • To learn how to prioritise protein, to ensure the only weight lost, is fat

Severe vitamin and mineral deficiencies can occur, these are prevented by

  • Taking mulit-vitamins, as recommended
  • Additional Iron if needed. Vitamin B12 injections or a spray if needed
  • Regular specific blood tests looking for mineral or vitamin deficiency annually

LRYGB: Risks and complications

The risks of LRYGB are low, if an experienced surgeon performs the surgery.



  • Is a risk with any major operation, but with LRYGB overall is below 1:1000

Peritonitis (severe intra-abdominal infection) can occur if one of the joins leaks

  • This is uncommon, risk below 1:200
  • Will usually occur in the first 48 hours after surgery, while in hospital
  • Would need further surgery and a prolonged hospital stay to fix it.

Bleeding can occur

  • ​1 in 100 patients bleed after the surgery
  • Mostly this is minor bleeding and may not need further intervention
  • It might be necessary to re-operate to control any bleeding
  • Very occasionally a blood transfusion, will be needed.
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