hi cc,
in the case of exercise, we create heat energy, which of course we lose, as we sweat. are you saying that we create more heat energy, from burning fat, than we do from burning carbs ?

whenever i have seen chemical equations for catabolic transactions, heat is shown only as an output.

one thing that we also need to realize is that all chemicals in the body are eventually burned as fuel, or excreted as waste. so all that energy that we intake, must be accounted for, at some point. so even if our body does not break catabolize the essential fatty acid at time of ingestion, it will at some point, get rid of it, so that potential energy is still there.

but i do not believe in the calorie concept, as far as health goes. i just chuckle a bit at what i find to be a rationalization for eating more of it. the bottom line is that we all need to find the correct amount of anabolic/catabolic nutrients that our body ultimately desires.