I'm going to call a girl in my class fat
Why would you call her fat?
She's fat and doesn't seem to see it.
It's rude to to say things like that to classmates. It just makes other people, not just her, want to stay away from you.
I mean, if you're fat, you're fat and that's that.
No matter how much someone weighs it doesn't give you the right to call them out.