Until last summer I was seriously hardcore about running. 60-mile weeks, marathon, college track and cross... I weighed about 145lbs. Last summer I basically switched over to primarily biking with running as crosstraining. Bike to work and back every day, MTB on the weekends. Running when there is light and I have time. I'm still in decent shape, but I weigh about 160 right now.
I only watch what I eat in that I try not to eat bits or dirt, glass, or metal.