There are populations that eat a high fat diet and have CHD. There are populations that don't. Maybe the premier example being the Masai who's diet consists almost entirely of animal fat. They have almost no heart disease. If you look at a chart of national per capita fat consumption and coronary heart disease rates, it is pretty much a scatter graph. Even in a fixed population, studies have shown that as fat consumption goes down, CHD rates continue to rise, and vice versa. I don't have a nice graphic of that close at hand, but here's one to make you pause. We are always told about the "French Paradox" in which the French eat a lot of fat and have low incidence of CHD. It isn't really such a paradox. From the UN sponsored MONICA study. Notice any trends?