Walter C. Willett, M.D., Dr.P.H., is the Fredrick John Stare Professor of Epidemiology and Nutrition and chairman of the department of nutrition at the Harvard School of Public Health, as well as a professor of medicine at Harvard Medical School. He is one of the leaders of the influential Nurses' Health Study, as well as the author of Eat, Drink, and Be Healthy: The Harvard Medical School Guide to Healthy Eating.