Is it a another myth or the inconvenient truth?

I heard from "ze wize grandpa" that too much can cause one to stop growing. Now i know, it sounds like a myth, YET the last year i have not grown a single centimeter, and people, i eat like a frickin horse! (Extra large family pizza with ease!) So, my friends, true or false??? O.o (btw, im 14, 15 next wednesday.. and yes.. i have a girlfriend, she has needs, so to speak.. haha)