Satisfying our hardwired instincts has been critical to our survival for as long as we have been human. That's why we eat when food is available, choose the most calorie-dense foods, and hate the feeling of hunger. Today, these same drives are leading millions down the path of obesity. But Dr. Susan B. Roberts, an internationally recognized nutrition researcher at Tufts University, shows how to turn our food instincts into an engine for permanent,...