I, a 15-year-old boy, clocked in at roughly 17-18% body fat with a weight of 146 pounds and me being roughly 5 foot 10-5 foot 11. Could this be holding me back from running faster in cross country? My PRs are 18:48 for a 5k and 18:39 for a 3 mile, but I have the speed for a 2:08 800m. Should I be aiming for a lower body fat or does it really not even matter?