The following procedures and tests will be done before surgery: routine standard tests required to be involved in the obesity surgery program (history and physical, blood work, ECG, nutritional assessment, psychological assessment and sleep study). During preoperative evaluation participants will be started on a medical weight loss diet with instructions provided by the program's endocrinologist, nurse practitioners and dietitians with the weight loss goals as stipulated by insurance companies and have a series of additional laboratory tests (blood work) done to test the hormonal response to weight loss.