First, I have to say how great it is that you're on the track team and doing that kind of sports. Not many girls at your age are that involved in discus or javelin. I wish I had more time for
sports and physical activity but it's not that easy at my age. I have to emphasize it again - losing weight would be the wrong thing for you. Maybe you just have to change your eating habits a little bit - try to avoid fat and coordinate your eating schedule. That will probably do the trick.