Gastric bypass surgery is typically performed on an obese individual. This bariatric type of surgery is performed to help the individual lose weight and live a healthier lifestyle. While gastric bypass surgery can be a life saving procedure, there is always the possibility of some complications of gastric bypass surgery. Complications may include gallstones, abdominal pain, diarrhea, and hernia. The complications may occur but are not too common. The positive results from the gastric bypass surgery tends to outweigh the possibility of any of these complications.