I thought it was more about her facial expression being happy and cute, with the implied joke we’re subverting being that girls take notifications of medical obesity well (happy) but notifications of something less bad for their health much worse (skull). I did not see the meme as trying to say that specific anime girl is medically obese.

I get where you are coming from too, though.

Fatphobes think everyone is unhealthy who does not have the proportions of anorexic women but without the anorexia (female), or isn’t a dehydrated musclebound hunk (male).