Food is measured in calories. People sometimes count calories and cut calories, and this week’s Please Explain is all about what calories are, how they’re measured, how we burn them, and if they differ from food to food. Joining us are: Dr. Kelly D. Brownell, Dean of the Sanford School of Public Policy and Professor of Public Policy at Duke University. And Russell Rising, Research Associate in the Metabolic Laboratory at the Obesity Research Center at St. Luke's-Roosevelt Hospital.