[crpatino]

I think you are ignoring the elephant in the room.

Active people have higher BMR because they build up bigger muscles. Not talking about bodybuilders - though that is the extreme of a continuous, but anyone who does regular exercise builds up some lean mass.

Off course, if you ever stop your body will pick up the signal and decide to not sustain the extra muscle anymore. If no change in diet follows immediately, you will pick up body fat pretty quickly.