Bariatric surgery is considered an effective long-term intervention for the treatment of obesity and associated complications. While bariatric surgery has been shown to result in a large sustained weight loss, the degree of weight loss and maintenance thereafter varies greatly. The Heads Up Surgical Demonstration Project (Heads Up) is a 5 year project examining weight loss after an intensive medical intervention (IMI) and the 2 most widely used bariatric surgeries (roux-en-y gastric bypass or RYGB and sleeve gastrectomy or SG). Baseline data are collected prior to surgery and follow-up data are collected at 6 months and annually thereafter. A recent meta-analysis revealed that RYGB resulted in greater weight loss and is more effective in resolving obesity related comorbidities than SG, although SG has been shown to result in a reduction of perioperative complications and reoperations1. Full elucidation of the mechanisms leading to variation in success for weight loss interventions is crucial to understanding the most effective and reliable treatments for obesity and associated comorbidities.