William H. Dietz, M.D., Ph.D., is Director of the Division of Nutrition and Physical Activity at the Center for Chronic Disease Prevention and Health Promotion of the Centers for Disease Control and Prevention (CDC). Prior to his appointment to the CDC, 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 in Boston, Massachusetts. Dr. Dietz received a bachelor of arts degree from Wesleyan University in Middletown, Connecticut, and his medical degree from the University of Pennsylvania in Philadelphia. Following an internship at Children's Hospital of Philadelphia, he spent 3 years in the Middle America Research Unit of the National Institute of Allergy and Infectious Disease in Panama, studying insect-borne viruses. After completing a residency at Upstate Medical Center in Syracuse, New York, he received a Ph.D. in nutritional biochemistry from the Massachusetts Institute of Technology (MIT).

In addition to his academic responsibilities in Boston, Dr. Dietz was a principal research scientist at MIT/Harvard Division of Health Science and Technology, Associate Director of the Clinical Research Center at MIT, and Director of the Boston Obesity/Nutrition Research Center funded by the National Institute of Diabetes, Digestive & Kidney Diseases (NIDDK) and was a member of the NIDDK Task Force on Obesity. He has served as councilor and past president for the American Society for Clinical Nutrition and past president of the North American Association for the Study of Obesity. In 1995, he received the John Stalker Award from the American School Food Service Association for his efforts to improve school lunches. Dr. Dietz also served on the 1995 Dietary Guidelines Advisory Committee. In 1997, Dr. Dietz received the Brock Medal of Excellence in Pediatrics from the New York Academy of Medicine and, in 1998, he was elected to the Institute of Medicine of the National Academy of Sciences. In 2000, he received the William G. Anderson Award from the American Alliance for Health, Physical Education, Recreation and Dance, and was recognized for excellence in his work and advocacy by the Association of State and Territorial Public Health Nutrition Directors. In 2002, Dr. Dietz was made an honorary member of the American Dietetic Association and received the Holroyd-Sherry award for his outstanding contributions to the field of children, adolescents, and the media.

Dr. Dietz's work includes the first study to demonstrate the relationship between television viewing and obesity, the earliest report that overweight was increasing among children and adolescents in the United States, 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 more than 150 publications in the scientific literature and the editor of three books, including A Guide to Your Child's Nutrition.