Understanding how excess weight can affect a person's overall health is vital to understanding the need for bariatric surgery. Being overweight means having extra body weight from muscle, bone, fat, water or a combination of these, while obesity is having a high amount of excess body fat. 

Bariatric surgery, also known as weight loss or metabolic surgery, refers to procedures, like gastric bypass, that limit the amount of food a person takes in or affects how a person digests food and absorbs nutrients. It is one of the most common bariatric surgery procedures. It is very effective in treating obesity and obesity-related diseases, such as diabetes, high blood pressure, sleep apnea and high cholesterol. 

In gastric bypass (also known as Roux-en-Y gastric bypass, a French term meaning "in the form of a Y"), the bariatric surgeon staples a person's stomach to create a small pouch in the upper section, then divides the small intestine into two parts and attaches the lower part directly to the small stomach pouch. The surgeon then reconnects the upper part of the small intestine to a new location farther down on the lower part of the small intestine. This procedure is difficult to reverse but can be done if medically necessary. Gastric bypass surgery allows a person to feel full sooner, absorb fewer calories and digest food fully. Bariatric surgeons perform gastric bypass through open, laparoscopic or robotic surgery.