I've never heard anything like that.
If I did, though...I've been sensitive since childhood about comments about my food. I just hate people commenting on it!

Usually it's well meaning enough, and I'm the one who ends up being rude.
For example I have had cashiers at the grocery store ask "having a movie night?" when they noticed I was buying popcorn and soda (back when I bought those things!). I shrugged non-committally, and refrained from saying what I really wanted to which was "None of your business! Why can't you just ring up the stuff and leave me alone?!"

If a server said I was eating a lot or asked "are you actually going to eat that??"...I know myself and I know I'd probably look at them like I wanted to kill them, and would definitely storm out.