Someone who eats a lot and loves eating is called .........
(Not a Teacher)
Gastronome, glutton, foodie, or gourmand fit the bill here.
If you feel like insulting someone, you could call them a pig or hog.
Of course in different cultures you may not find the exact usage, but I might have searched.
This reminds me of an Iranian video I found teaching English conversation. In one of the set pieces, the guy opens up with, "You're getting fat."
I almost keeled over laughing. It's just so tactless to say stuff like that in polite conversation. Honestly, you need to be pretty close to someone to even broach that subject. You'd say something like, "I noticed you've been gaining a lot of weight lately. Is something going on?"