That right there is, I think, the heart of the whole issue. That and the fact that it's human nature to be very reluctant to change your mind on what you believe to be true and in fact, have probably believed to be true for the majority of your life, even in the face of overwhelming evidence to the contrary. How many posts have we all seen here titled: "Help! I'm afraid to eat fat!"? While doctors and scientists are supposed to be objective and analytical, they are still human (yes, I know some would disagree with me on that). Face it, most people find change threatening or at the very minimum uncomfortable, especially when it is being forced on them and not their idea. Changing your mind on what you have believed for a very long time to be true is still change.