Obesity is an epidemic - more than 40% of the United States population suffers from obesity and, as such, it has a high burden of weight-related conditions and diseases.  Metabolic and bariatric surgery has proven to be the most effective and durable treatment of severe obesity.  Technological advances including applications of laparoscopy, robotics and endoluminal techniques have rapidly advanced this field.  Data and outcomes examining treatments have also improved and, as providers, we have a wide spectrum of therapeutic options to treat patients. As techniques and outcomes change rapidly, access to a comprehensive yet focused resource regarding bariatric surgery is currently limited.  The third edition of this manual is designed to present a comprehensive and state-of the-art approach to the current and future status of metabolic and bariatric surgery.  Sections will address the evolution in specific treatments available to patients, initial evaluation, and selection of procedures for individual patients, the latest surgical and endoscopic techniques being employed to treat patients including data on outcomes, and future directions for therapy.  In particular and unique amongst references, a major focus of this text will be on both the bariatric and metabolic bases of therapies and outcomes.