> but a pure thermodynamics view assumes if you eat an extra 1000 calories that it will be stored as fat, does it not?
Replace "will" by "might", and you're there. Thermodynamics just say the energy must go somewhere, but whether it's your fat cells or your excrements (or maybe some other channel I'm not aware of right now) is a matter of medicine.
body heat
whole point of having high metabolism is your body simply gets rid of excess energy by heating up(100W on average?). Its burning calories while you sleep.
Replace "will" by "might", and you're there. Thermodynamics just say the energy must go somewhere, but whether it's your fat cells or your excrements (or maybe some other channel I'm not aware of right now) is a matter of medicine.