My understanding is that the Calories in each bit of food are intended to be "the amount of energy you absorb" (on average, I guess? in the same way that averag

My understanding is that the Calories in each bit of food are intended to be "the amount of energy you absorb" (on average, I guess? in the same way that averages are used for how many you burn when exercising). So a better synonym than "energy" for Calories as used in nutrition might be "usable energy" (excluding the energy content of the food that you poo out).