Want to learn more? Here is a good collection.
Why We Get Fat: And What to Do About It -- by Gary Taubes. This is the short and readable version of "Good Calories, Bad Calories". It's a real eye opener.
The Art and Science of Low Carbohydrate Living -- by Stephen D. Phinney, Jeff S. Volek. This book is where I learned the most about the ketogenic diet and it's effect on the body. Without it, this calculator would not exist. Highly recommended!
The Ketogenic Diet -- by Lyle McDonald. This is not the typical diet book, it teaches you everything you should know about this diet. Lyle McDonald is an expert in dieting and training has a lot of experience.
Good Calories, Bad Calories: Fats, Carbs, and the Controversial Science of Diet and Health -- by Gary Taubes. This is probably the main reason why the ketogenic diet became so popular recently. It thoroughly debunks the 'fat is bad' myth and backs this up with more scientific references than you will ever care to look up yourself.
The Art and Science of Low Carbohydrate Performance -- by Jeff S. Volek, Stephen D. Phinney. This is a follow up book after Low Carb Living, and while it is a small book it is so packed with information that you'll probably have to read it multiple times. Fantastic for anyone who wants to exercise as well.
Fat Chance: Beating the Odds Against Sugar, Processed Food, Obesity, and Disease by Robert H. Lustig.