It’s all thermodynamics. You are nothing but a big bag of hot water ( you are 70% water ) with thermostat set at 98.6 Deg. F. Figure it out. Calories are the fuel. It doesn’t matter what the calories are, carbs, protein or fat.
“It’s all thermodynamics.”
That is simply untrue. The law of thermodynamics refers to a CLOSED SYSTEM. We are not. One might as well argue gas mileage is independent of engine efficiency and aerodynamics.
Dr. Jason Fung - ‘Therapeutic Fasting - Solving the Two-Compartment Problem’:
https://www.youtube.com/watch?v=tIuj-oMN-Fk