I'm sorry, but in the first photo of a younger Cheryl that Polly attached to her post, Cheryl is not 'slim'. Judging by her face, arms and midriff, she looks to be carrying about the same amount of body fat as I was very recently, with a BMI of 27-29. That is not slim, nor is it healthy.
I'm not getting the continued use of the word 'skeletal' by Rousette, either. She looks thin to me, but the only reason I can think of as to why it says 'unhealthy' to me in any way is because I'm not used to seeing so much of the bone structure in her face (which is completely a normal amount for many other people), and also because she seems to have changed her make-up/had her teeth done/something that makes her look far more like what I can only describe as a Spanish TV show host. It's just a different look she seems to be going for, in some ways.
I also accept that I have no idea of her eating habits, no idea what kind of work she has had done recently that might have dramatically changed her overall look in a way that some people might immediately associate with 'oh she must be starving herself/ill', and also no idea exactly how thin she looks IRL, given that photos (and outfits!) can give very misleading impressions.