Just out of curiousity if/how long until i see results?

So im 12. Weigh 102 which according to my height is the 62% for my bmi or whatever. I just joined cross country and ive been doing it about a week. we never run less than 2 miles. Im also a competitive dancer. bout 7 hours a week. so my question is well since i use to dance only 3 hours a week and not do so much running and ive also stopped eating junk food COMPLETELY do u think i culd possibly loose weight? just out of curiousity like i said but ya...