skinny is nice but there is such a thing as too thin.
Dude, some people just don't work that way. My brother and I are as skinny (or skinnier than, sometimes) as many girls our age. Just "eating something" won't help, sorry. Anyway, that's not even close to anorexic (I realize you didn't say that but I figure that's what you're implying) or anything - if it was, I would also be considered anorexic, but I'm perfectly healthy.