 The study will be designed to compare two cohorts of patients that will undergo laparoscopic RYGB. Cohort 1 will include ESRD patients on HD who meet the NIH guidelines and preoperative requirements for RYGB. Cohort 2 will include non-ESRD patients who meet the NIH guidelines and preoperative requirements for RYGB. Laparoscopic RYGB will be performed in ESRD patients who meet the guidelines recommended by the National Institutes of Health consensus statement . This includes patients who either have a BMI40 kgm2 or have a BMI35 kgm2 and have a significant morbidity attributed to their obesity i.e. sleep apnea, hypertension, and diabetes mellitus. All patients will undergo a complete pre-operative evaluation inclusive of dietary instruction, assessment of surgical risk, psychosocial evaluation and compliance evaluation. This evaluation will be conducted through an existing infrastructure at the investigators Bariatric Surgery Center. Patients will be required to be on hemodialysis or able to be converted to hemodialysis for the perioperative period. All procedures will be performed by the same team of surgeons, experienced in both laparoscopic RYGB, organ transplantation and general surgery in ESRD patients. The risks involved with Roux-en-Y gastric bypass surgery will be discussed with the patient. These risks are inherent to the procedure, however the procedure is being conducted for medical appropriate reasons and therefore the benefits to the procedure outweigh the risks. At the present time, it is believed, without any justification, that this procedure is more risky or too risky in the ESRD population. A primary objective of this study is to investigate this question. 