Boring question #88: Those men/women who are attracted to anorexic women, what makes them physically attractive?

Seeing that not many men (at least that are seen) are anorexic this question will focus on anorexic women. To those men (and maybe a few lesbians who like anorexic women) what physical attributes make anorexic women attractive? For instance, is it that skin-stretched-over-a-skeleton look, knobby knees and elbows, being able to count each rib, thin skin that you can see veins under, etc?