If your friend said you'd lost too much weight and that you used to be perfect, would you consider that rude?

Depends how skinny they got. If they were healthy and went anorexic skinny i would also be worried. I see where it can come off negatively with the word perfect but its a word my bf and grandmother would always say. Youre perfect.

Yes! I've seen it happen to relatives. I thought maybe the friend was envious, at least subconsciously.

No