One of the common side effects of gastric bypass surgery is gas. While it is under publicized, gas remains one of the main side effects of the disorder. Flatulence is seen in many cases because of the bowel changes that one undergoes when one gets the surgery. By the time the food reaches the colon, the bacteria and enzymes go nuts trying to digest the food. This creates a lot of unpleasant side effects like gas and farting. While it is not talked about much because it is so embarrassing, it should be investigated to see if the person really wants to put up with it after surgery.