When I compare these pictures of someone suffering with anorexia to Cheryl I can see that she is not as extremely thin as the poor unknown woman. She is not a big step away from being extremely thin though. Her back and ribs are similar to the other woman's.
Cheryl is not just slim at the moment she is thin. I agree that many people are too heavy at the moment but arguing that Cheryl's present figure (as opposed to her healthy, slim figure of ten years ago) is 'normal' is wrong.
It's not even 'normal' for her.
Cheryl is held up as an aspirational figure to us. She has wealth, beauty, a fabulous lifestyle, beautiful clothes. Unless we notice her face, her figure, her clothes she can't maintain her profile and without her profile she doesn't have a career. If she wants us to notice her appearance she can not complain if people express opinions.