there are many other factors in this. your body requires food for energy to function. so weather your exercising or just sitting there you are still going to need energy just to make your organs work. Also depends on your metabolism. if you dont do anything all day long you dont need many calories to support that. now if you are active you will need more. If you sit around all day and eat alot thats when the balance gets nocked off. your intake is higher than what your burning so your body stores it as fat. you process whatever you eat. and your body takes what it needs for energy and whatever is left is stored as fat. if you dont have enough fuel it turns to its reserve tank, and starts burning fat, and well muscle if its really low on fuel.