Gastric bypass is one type of weight loss surgery. In gastric bypass, what we do is we cut your stomach and make it into a small pouch. The pouch then becomes about the size of a small egg. In addition, we also cut your small intestines and reroute them, and reconnect them to that small pouch. This way, when you eat you're going to eat food and you're not going to nearly be able to eat as much as you could before.
You're going to eat food, it's going to fill that small gastric pouch and then the food's going to go directly into your small intestine, and your food is actually not going to be fully digested and therefore, the calories aren't going to be absorbed for several centimeters, about 100 centimeters until we again, connect your intestines later down.
Then you'll start absorbing the calories in the food that you eat, so for this reason, we say that gastric bypass has a malabsorptive component. In terms of weight loss after gastric bypass, it's pretty drastic. We say that a patient loses about 70% of their excess body weight within a year, so that could be about 100 pounds for you of weight loss after a year.
Some things that you need to know about gastric bypass is you definitely need to make sure that you eat enough protein after gastric bypass, because of the malabsorptive nature of the surgery. In addition, you'll need to take a multivitamin, Vitamin B12, and many times, iron and calcium as well. So you need to follow up with your surgeon regularly, to make sure that you are eating healthily and getting the vitamins and the nutrients that you need. That's a basic overview of how gastric bypass surgery works.