I absolutely agree, Anna. In this article, I'm talking strictly about congratulating someone for losing weight when you know it was a deliberate, healthy effort (I'm not counting eaing disorders, of course), which is the case with Adele, Rebel Wilson, and me. I wouldn't dream of randomly congratulating someone for losing weight when I don't know the circumstances. That would be sort of like asking a woman if she is pregnant, which in my book, is a no-no.
Out of curiosity, when you say you try not to comment on someone's appearance unless it's something they chose, does that mean you wouldn't compliment a person's eyes or smile? Personally, I don't mind those kinds of complimets, but I prefer to be complimented for personal achievements and not acts of nature.