A calorie is a measure of energy based on how much something can be burned. Your body isn't a steam engine, it doesn't burn the food you put into it. It breaks it down for various different purposes using various different chemical processes. Yes, some food goes into giving you energy, but some also goes to healing wounds or growing your fingernails or hair. Some of it goes into fueling bodily functions like the menstrual cycle or the digestion process itself. Certain things require certain types of food, for instance the brain runs mostly on carbs and sugars. Not every excess calorie turns into fat, some of it is excreted as waste or is used to raise your body temperature (hence why you sometimes feel warm after a big meal). A fire burns anything you put into it and turns it directly into energy. Your body doesn't work like that. Different people digest different things in different ways. You don't need to count every calorie and use up the excess, your body is smart and will store what it needs. Listen to your body and not oversimplified calorie labels.