I told my friend to eat less if she wants guys to like her
Have you said this to her before?
Of course, I warned them that would happen.
I don't think they need to hear it a second time, then! You shouldn't be telling your friend how to live their life in the first place. Let them make their own decisions!
Sounds like you have a lot of thoughts about the way I've spoken to my friends.
Telling someone nobody will love them because they are fat is a horrible thing to say. There are many people attracted to all sorts of body times.