I hear this term quite a lot - "if you exercise it will boost your metabolism". The implication generally being that if you do some exercise not only will the exercise burn some calories, but you will also continue to burn more calories throughout the day.
This doesn't make much sense to me. We store calories so that we have some reserves to draw on when needed. If we burn a load of calories, the body wouldn't just think "oh ok, I'll just off load some more for the hell of it". I'm sure it would be the opposite, it would see you exerting yourself and think it would need to hold on to the calories to be used when you exert yourself again.
So, what does boosting your metabolism actually mean?