Laparoscopic Roux-en-Y Gastric bypass

Laparoscopic Roux-en-Y Gastric bypass (with or without silastic ring)

Gastric bypass surgery provides the most robust long term weight loss and has the best outcome with resolution of diabetes. After the surgery, most diabetic patients are able to cease their diabetic medications within hours of the operation. Bypass also has the most dramatic effect on lowering triglycerides and cholesterol. The bypass procedure is extremely effective at treating gastro-oesophageal reflux disease, in fact it is becoming common to perform a bypass in patients with severe debilitating reflux who have failed medical therapy and even prior operations for reflux. It is also a salvage procedure for those who have had complications with prior bariatric procedures.

How is the Operation performed?

There are two components to the procedure. First, a small stomach pouch, approximately one ounce or 30 milliliters in volume, is created by dividing the top of the stomach from the rest of the stomach. Next, the first portion of the small intestine is divided, and the bottom end of the divided small intestine is brought up and connected to the newly created small stomach pouch. The procedure is completed by connecting the top portion of the divided small intestine to the small intestine further down so that the stomach acids and digestive enzymes from the bypassed stomach and first portion of small intestine will eventually mix with the food.

What is the mechanism of weight loss?

There are various styles of gastric bypass, the most common is the Roux-en-Y gastric bypass. This procedure is the most common procedure worldwide and is gaining popularity in Australia due to its strong longer term effect on weight loss. The procedure takes about 2 hours for a primary procedure, and generally requires one or two nights stay in hospital.

The gastric bypass works by several mechanisms. First, similar to most bariatric procedures, the newly created stomach pouch is considerably smaller and facilitates significantly smaller meals, which translates into less calories consumed. Additionally, because there is less digestion of food by the smaller stomach pouch, and there is a segment of small intestine that would normally absorb calories as well as nutrients that no longer has food going through it, there is probably to some degree less absorption of calories and nutrients.
Most importantly, the rerouting of the food stream produces changes in gut hormones that promote satiety, suppress hunger, and reverse one of the primary mechanisms by which obesity induces type 2 diabetes.


  • Produces significant long-term weight loss (60 to 80 percent excess weight loss)
  • Restricts the amount of food that can be consumed
  • "Dumping syndrome" if foods high in sugar or saturated fats are consumed
  • Good operation for sweet eaters
  • May lead to conditions that increase energy expenditure
  • Produces favourable changes in gut hormones that reduce appetite and enhance satiety
  • Typical maintenance of >50% excess weight loss
  • More successful then gastric band in keeping the weight off long term
  • Faster improvement with glycaemic control in diabetics


  • Is technically a more complex operation which potentially could result in greater complication rates
  • Requires adherence to dietary recommendations, life-long vitamin/mineral supplementation, and follow-up compliance
  • an lead to long-term vitamin/mineral deficiencies particularly in vitamins B12, iron, calcium, and folate

Ideal patients:

  • Patients with diabeties.
  • Patients with high triglycerides or cholesterol.
  • Patients with reflux disease/GORD.

Expected Weight Loss following Gastric Bypass

Approximately 60-80% of excess weight can be lost if the general rules pertaining to lifestyle modification are followed postoperatively. Some weight regain is commonly seen at 18 months but sustained weight loss in the order of 50% of excess weight loss is generally seen at 5 years and beyond.
Most weight loss is seen in the first 12 months. Sometimes it can be precipitous which is not of concern as long as vitamins and adequate protein, 60-80g, per day are taken.
Sometimes patients plateau for periods and do not lose weight. This may last from a few weeks to longer but weight loss resumes as long as the correct lifestyle modifications are being followed.