4:30 PM ET and Sunday at 7:30 AM ET. (CNN) -- "To eat, or not to eat?" For many people these days, that really is the question. For the past four decades, we've been told to stay away from red meat, dairy and cheese -- foods high in saturated fats -- because saturated fat is bad for the heart. But investigative reporter Nina Teicholz says that isn't the case. "When the dietary recommendations came out in 1961 saying that saturated fat causes heart disease, that was based on total cholesterol," Teicholz said. "But our understanding of heart disease has evolved...