Obesity has been predicted to become the number one health problem worldwide in the next decade. Important progress has been made to discover the causes of obesity. In this volume, recent advances in the etiology of obesity, including its pathophysiology and the current nutritional treatment of obesity as well as medications used to treat obesity, are reviewed. Special attention is given to bariatric surgery. This surgical option for the treatment of obesity including reconstructive surgery associated with massive weight loss is discussed in detail. Several nutritional strategies and diets are also reviewed. The psychosocial aspects of obesity, cognitive behavior therapy and interpersonal therapy for people suffering from binge eating disorder that help sustain the benefits of bariatric surgery over long term are also discussed. This publication gives physicians and healthcare workers, including nurses, social workers and psychologists, valuable information for dealing with their patients and making them aware of the latest advances in obesity research.