I actually don't think most of do look ill. On the very lowest scale of healthy bmi probably, but not ill. You can see definite muscle definition, which disappears in anorexics (ask me how I know?), and I'd say that the most gaunt facial features amongst them have been enhanced by contouring.
Granted, they are all of a particular body type, but to be snide about them not being paid enough to eat? Not really on. Like I said, I would be slaughtered (rightly so), were I to go on about plus size models being walking adverts for why not to eat McDonald's, and looking like they're five minutes from a heart attack.