Know Your Fats: The Complete Primer for Understanding the Nutrition of Fats, Oils and Cholesterol by Mary G. Enig

This is quite simply the best book available on lipid chemistry in nutrition that is accessible to non-scientists. It lists and describes the actions of fats in our diet, and the role fats play in our body chemistry and health. Dr. Enig takes us all the way from chemical formulas and molecular diagrams to descriptions of various kinds of oils and fats used in cooking, as well as the sources and makeup of different types of oils and fats.
Dr. Enig pulls no punches in discussing misunderstood or misused research, and this honesty is welcome and refreshing, not to mention possibly life saving. It is so tiresome trying to wade through the hype and PR noise around nutrition. Like medical research, the food business is about Big Money, and truth seems to be a stranger to that part of our society. More and more, one must become an informed advocate for one's own health and welfare. This book is an important tool for the enlightened consumer.
The book is well written in a very clear style with no extraneous scientific jargon. It is well referenced and cited, which I like in a book that discusses scientific research. These days people have much more access to original research papers than ever before.
If you get only one book on fats in your diet, this should be it. The research and information is solid, free of fads and commercial influence.