Obesity in childhood and adolescence has reached epidemic proportions in all industrialized countries around the world. Its impact on individual lives as well as on health economics has to be recognized by physicians and the public alike. Among the most common consequences of obesity in the adolescent are hypertension, dyslipidemia, back pain and psychosocial problems. Therapeutic strategies include psychological and family therapy, lifestyle/behavior modification and nutrition education. The role of regular exercise and exercise programs is emphasized. Surgical procedures and drugs used in adult obesity are still not generally recommended for obese adolescents. This book aims to increase physicians´ knowledge and understanding of obesity in childhood and adolescence as well as to further public awareness of the health burden and economic dimension of obesity at a young age. Several chapters deliver insights into the basic understanding of which factors contribute to or prevent the development of overweight and obesity in young people. Other contributions provide tools for the clinician to manage the care of the child and adolescent with overweight/obesity. In addition, knowledge from the latest scientific studies on the molecular biology of obesity is also presented.