Dr. William H. Dietz is the director of the Division of Nutrition and Physical Activity at the federal Centers for Disease Control and Prevention in Atlanta. Prior to his appointment, he was a professor of pediatrics at the Tufts University School of Medicine and director of clinical nutrition at the Floating Hospital of New England Medical Center Hospitals. His work in the field of pediatric obesity includes the first study to demonstrate the relationship between television viewing and obesity, the earliest report that overweight was increasing among U.S. children and adolescents, and the first suggestion that critical periods exist for the development of overweight in children and adolescents. His research has focused on the epidemiology of childhood obesity, the clinical consequences of childhood and adolescent obesity, optimal dietary therapy for overweight children and adolescents, and the implications of reduced energy expenditure for the development of overweight in children and adolescents. He is the author of over 150 scientific publications and the editor of three books, including \"A Guide to Your Child's Nutrition.\" He received his B.A. from Wesleyan University, his M.D. from the University of Pennsylvania and his Ph.D. in nutritional biochemistry from Massachusetts Institute of Technology.