Cathy Nonas, M.S., R.D., C.D.E., is director of the VanItallie Center for Nutrition and Weight Management, an arm of the New York Obesity Research Center at St. Luke's-Roosevelt Hospital Center in New York City. The Obesity Research Center is one of four federally funded centers for investigating the causes and treatment of obesity in the United States. Julia VanTine is a health journalist whose most recent books include "Maximum Food Power for Women" and "Energy for Everything: Rejuvenation for the Mind, Body, and Soul,"