[tester89]

I have seen this claim, but what I don't understand is, then how does the body actually fuel the exercise.

Surely someone who sits at home for a all day would burn fewer calories than someone who exercises?

I can understand, that if someone does exercise for 1 day and then quits, that day the body may compensate for the extra energy requirement by reducing its own metabolic activity, but I assume that couldn't last if someone exercised regularly.