Calories in, calories out is a valid model. It's just not a very useful one. The reason that some foods are better than others even though they have the same nu

Calories in, calories out is a valid model. It's just not a very useful one. The reason that some foods are better than others even though they have the same number of calories is that some foods give you the feeling of being full, which causes you to eat fewer calories later (e.g. protein). Or some foods might cause you to feel fatigued, causing you to burn fewer calories later (sugar crash). But don't kid yourself, if it's a given that you eat X calories and burn/lose Y calories, then you'll gain weight proportional to X-Y. Choose foods that make it easy to keep that number close to zero.