Why do teenage guys have to be so shallow?

I'm a junior in high school. I'll tell you right now i'm not skinny at all. I'm a very big girl. But i'm also proportionate. I'm not gorgeous, but not hideous either - semi pretty. But none of the guys at my school would even give me a second look and not get to know me. My school is comprised of mostly white, rich families. Why is it that so many teenage boys are shallow enough not to even look at me? I just asked a kid to our homecoming dance who isn't even attractive or skinny himself and he said no. What's up?