Obesity is an important public health issue worldwide. In the United States, the percentage of overweight and obese adults increased from 47 and 15%, respectively, to 69 and 36% in the last 40 years. Medically supervised attempts at weight loss are fraught with failures and recidivism. Surgical approaches to this important issue are both durable and effective. The gold standard approach to the surgical treatment of obesity and the attendant medical comorbidities is the laparoscopic roux-en-y gastric bypass (RYGB) and the laparoscopic sleeve gastrectomy (LSG). The mechanisms by which these two operations work and the associated side effects are not completely understood. It is established that the RYGB induces changes in both the fatty tissue mass (FTM) and lean body mass (LBM) post-operatively. This is associated with decreases in bone mineral density, basal metabolic rate, and potentially the ability to maintain weight loss. There is only incomplete information on the influence that the LSG has on body composition. This study proposes an evaluation of the changes in body composition that occurs following these two disparate operations. Using serial measurements by the BodPod and collecting information on the patients' dietary intake, exercise habits and comorbidity resolution, this study will help to better define the influence that the LSG has on body composition. It is hypothesized that the addition of a malabsorptive component will result in increased speed weight loss and overall weight loss which will have a negative impact in the preservation of lean tissue mass for the patient. This information can then be used by bariatric surgeons to better cater the surgical procedure and post-operative plan to the patient's body make up and medical comorbidities.