This is the hard thing about the "calories in/calories out" statement, it's accurate for a specific thing: the calories of energy in a burnable form available to your body/the direct burned calories as a combination of RMR and exertion.
The issue of course is that we use it in the context of different kinds of food and a simplistic assumption about how effective we are at converting a calorie in each into a burnable form.
2000 calories of energy from custard will be processed, stored and used differently than 2000 calories of energy from chicken.
The issue of course is that we use it in the context of different kinds of food and a simplistic assumption about how effective we are at converting a calorie in each into a burnable form.
2000 calories of energy from custard will be processed, stored and used differently than 2000 calories of energy from chicken.