Well I think the less you carry around a course the better you'll do in terms of the finishing time. I can't give you any science or stats though...just personal experience. I don't think your build makes much of a difference...you see all types running and all types running well. Having some natural ability helps but good old fashioned hard work...ie lots of training/drinking less and eating well can get you a long way. I'm no natural athlete fior sure!

so with all this talk about weight loss, bearing in mind my lack of running experience as i'm a bit green on these things.
How important is your weight? i mean, if i'm lets say 7lbs (old money) heavier than i was a year ago, would it really slow me down much?
also do certain types i.e tall and thin or short and stocky or? whatever build have a better natural ability to certain types of running?