Preaching to the choir, I've been paleo for three months and lost almost 40 lbs. I'm just talking about the physics involved: caloric energy used vs. caloric energy consumed. If you could measure them perfectly, there would be a loss.
Again, how do you know?
Below someone says diet follows the laws of thermodynamics. That's hogwash. While our bodies certainly follow all laws of physics, that has nothing to do with diet.
We are perfectly capable of expelling unconsumed dietary energy.