I am a 17 yo female, been running since I was 12, pretty mediocre times (19:36 5k, 5:36 1600). I have had a series of stress fractures and other injuries over the past 2-3 years that have hindered my progress a lot and contributed to unwanted weight gain (despite lots of cross training). I currently weigh about 170 at 5'9", have the muscle mass that looks more like a rower or rugby player or something. So my body fat percentage isn't that high - probably between 20 and 25 percent - but still too high. I want to lose quite a bit of weight to help me run pain free. I stop menstruating around 140 lbs and under (used to be anorexic). How much weight should I be aiming to lose? How much time could I take off my mile if I got down to 145ish and trained consistently? (The 5:36 was at 165 lbs on 10 miles per week running) thanks!