“You’re so skinny. Or fat. Or short. Or whatever.”
We are actively living in the cancel culture, when saying things like that is just inappropriate to the end of the world and back. So, if you didn’t know it by now, don’t EVER express your opinions about someone’s appearance like that.
If you’re truly eager to say what you want to say about a person’s appearance(although you should try to shut up), at least make sure it’s accompanied by a compliment. Or, as an alternative, try your best in showing how imperfect you are as well. Don’t want to do that? That’s perfectly fine. Don’t do it to others then!