If you only read one book in your lifetime, read Good Calories, Bad Calories: Challenging the Conventional Wisdom on Diet, Weight Control, and Disease, by Gary Taubes. This meticulously researched book takes the prevailing low fat diet recommendations apart bit by bit. Rather than present a full review of this book I am simply going to recommend it.
Gary presents a well researched and resourced account of the history of the low fat diet and the bad effects on our health and mortality.
Read Good Calories, Bad Calories; it might save your life or at the very least suggest to you a way of eating that will reduce your risk of succumbing to a disease of Western Civilization.