Prior to having gastric sleeve surgery, patients are put on a highly limited diet to assist shrink their liver. Then, a few days prior to the procedure, they switch to an all-liquid diet. A section of the patient’s stomach is removed during gastric sleeve surgery, limiting its capacity to around 25% of its previous size. The patient’s ability to eat has decreased, and the food they do eat takes longer to digest. A special diet must be followed after gastric sleeve surgery to allow the stomach time to recover, and then a healthy diet must be continued for the rest of their lives in order to maintain their weight. Rapid weight reduction results from the bariatric surgery patients’ “all liquid” diet, the period of time required for the stomach to recover, and the decreased stomach size.