I too enjoy running and even at my heaviest (105kgs or 231lbs) I could happily run 5kms - sorry don't know how much that is in miles.
I would'nt say I run that fast now, but I love it.
I found even eating like a pig running helped me maintain my weight and when I did Atkins and ran together I was losing a kilo a week consistently.
Unfortunately I am currently off the Atkins wagon and trying to climb back on.