Allow me to introduce myself wrote:
I'm 5 foot 8 and a half inches, I currently run 75mpw (average) on doubles and I weigh 125 (after a 4 or 5 mile am run, where I usually weigh myself). I will be averaging 90mpw in about 7 months, by that time, would it be normal for me to be 118-120lbs?
Some extra info:
I do eat a very clean diet (mostly high carb low fat), and I probably have about another inch to grow according to the doctor. I do about 2 hard workouts per week. I am a sophomore in college, and my PRs are 14:40 and 31:0x.
I plan to do marathons post college, so any advice in that direction would also be great.
It's not unhealthy... until it is very unhealthy. It's a fine line (and different for everyone). But if you do get too thin and then get sick/injured, it is a long road to recovery. Do yourself a big favor and hold on to an extra few pounds.