I guess I'm a pretty average weight for my height and age - almost 18, 5' 11", 140 lbs. I do have a high metabolism, but that doesn't play too big of a role on my weight. What's funny is, I can tell if I need to eat something when my pants begin to slip (even with my belt on) and my ribs start to show.
Of course, I also skip/skimp breakfast on a regular basis.