just run. do push ups, sit ups, whatever. run to lose fat. there will be a certain amount of fat you will be able to lose, though, but still, it's the best you can do.

and for weights, don't overdo it. i was using heavy dumbells for both punching power and increased shooting range in basketball, and it was alright, but i overdid it and i couldn't move too good, even when my muscles didn't hurt.