The Hacker's Diet, if I recall correctly, puts forth the notion that "a calorie is a calorie." Whether this is correct or not is an on-going controversy, but I happen to think that it is an incorrect understanding. 300 calories of extra virgin olive oil and 300 calories of SweeTarts do not affect your body or your weight the same way.
User `fb03` recommended this yesterday on another thread. What a wonderful book! Although it doesn't say anything you didn't already know - to lose weight, eat less - it is really well written, and puts the whole process into perspective. A lovely book for engineers who want to stop being overweight.