OK, I'm not a highschooler and I'm not a guy ... I'm your great grandmother!! Anyhow, can you pick up your burger and just sort of suck the meat and cheese and mayo out of it and leave most of the bun behind? That's not quite as conspicuous as trashing the bun before you start to eat, and you just might get away with it not being noticed!

Good for you, taking control of your eating habits before they get too out of control. I wish you the very best of luck in your future!