Here's an excerpt from a great interview with the author:
Eating less animal fat hasn't made us healthier or thinner. We have reduced the amount of animal fat we eat, but statistics show the total amount of fat in our diet has increased. Vegetable fats have been replaced by animal fats, which has resulted in a huge increase in polyunsaturated fat in our diet (which can depress your immune system). We've also added man-made trans fats to the mix, which everyone now agrees are not good for us.
It's difficult to blame obesity on one thing. But it is definitely not consumption of animal fats. I think there are many causes -- the way we eat, alone, in the car, walking down the street, the constant snacking. Increased consumption of low-fat, fat-free "foods" results in us eating more sugars and carbohydrates. These products don't satisfy our hunger and leave us wanting to eat more. Eating good animal fat does, so you eat less.
Yes. Yes, yes, yes! I am so excited about this book! Go read the article. Lots of good stuff there.