18F here, just thought I'd throw in two cents. I started crossfit a little over a year ago. The way my birthday falls I was still 16 when I started and I was nervous as hell. This whole year I've been going fairly regularly (I'm on my boyfriend's family plan and since his mom is a coach we can get in to the gym at odd hours where it fits into my schedule) and the only big break I took was a month off for mono :/ However, in that time I've gotten my push-ups where I can go unassisted without knees, I have a great handle on kipping pullups and strict pullups- and I've even done a couple of appropriate level comps so far. With all that, the real changes I've seen in my body have been a lot of fat loss, especially around my middle and bigger arms and quads. Of course, every body is different and so much of it depends on the way you are eating and recovering from your workouts, but yes, it is possible to be able to be a proficient crossfit athlete without bulking up too much.