[arghnoname]

I ran 15 miles on Monday at a pretty relaxed pace (took 2.5 hours). My watch, while probably not perfectly accurate, nevertheless suggested I burned approximately 1640 additional calories during this time.

This is 1/4 as much as 10 hours and is a significant proportion of my basal metabolic expenditure.

On a more typical day, I may run closer to an hour and be closer to 600-700 calories. I'd still call this significant.

You can burn significant calories exercising, but the exercise is probably kind of unpleasant.

[ekianjo]

Good. What I mean is that it is a lot more effort than cutting down on an extra snack. Running a hour for 600 calories does not sound like its very effective since its just about the calories of 2 cookies.