They know that a diet high in animal and dairy fat causes heart/circulitory disease. That was deduced from a study more than a 1/2 century ago of a small, relatively isolated community in Scandinavia, IIRC, that had a significantly high incidence of early and severe heart problems. Their diet consisted mostly of high fat dairy products and beef. Yes Cheese Cake and Filet Mignon kills. Of course, the answer is moderation. Even with the majority of our population overwieght and eating a poor diet, our life expectancy continues to go up every year. An interesting fact, the average American is 26 pounds heavier today than they were 60 years ago. That's a lot of extra lard that some of us are carrying around.