The "calories in/calories out" argument is based on the assumption that the human body is a closed system. This is simply not the case, and touting it as a diet strategy is irresponsible. You might lose weight if you lower your caloric intake by only eating 1 McDonalds cheeseburger a day instead of 2, but in the end you are still eating crap food "product", and you won't be as healthy as you could be by focusing on the _quality_ of your food as opposed to the _quantity_.