The Roux-en-Y Gastric Bypass – often called gastric bypass – is considered the ‘gold standard’ of weight loss surgery and is the most commonly performed bariatric procedure worldwide.
Gastric bypass surgery shrinks the size of your stomach, so you can't eat as much as you used to. The surgeon will also re-route, or bypass, part of your digestive system so you don't absorb as much food.
There are several types of gastric bypass surgery:
Roux-en-Y gastric bypass: This is the most common gastric bypass surgery done in the U.S. Surgeons can do it through a small cut, which has a quicker recovery time than more complicated surgery. First, the surgeon makes a small stomach pouch by stapling part of the stomach together or by vertical banding. This limits how much food you can eat. Next, the surgeon attaches a Y-shaped section of the small intestine to the pouch. That creates a bypass for food, so it skips part of your digestive system. As a result, you absorb fewer calories and nutrients.
Extensive gastric bypass (biliopancreatic diversion): This is a more complicated type of gastric bypass. The surgeon removes the lower part of the stomach. He then connects the small pouch that remains directly to the last part of the small intestine, completely bypassing the first two parts. It works for weight loss, but it's not widely used because it can leave you short on nutrients.
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.
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 fewer 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 type2 diabetes.
Produces significant long-term weight loss (60 to 80 percent excess weight loss).
Restricts the amount of food that can be consumed.
May lead to conditions that increase energy expenditure
Produces favorable changes in gut hormones that reduce appetite and enhance satiety
Typical maintenance of >50% excess weight loss
It is technically a more complex operation than the AGB or LSG and potentially could result in greater complication rates
Can lead to long-term vitamin/mineral deficiencies particularly deficits in vitamin B12, iron, calcium, and foliate
Generally has a longer hospital stay than the AGB
Requires adherence to dietary recommendations, life-long vitamin/mineral supplementation, and follow-up compliance