in grade 8 i used to do the same thing! every single day i ate in the bathroom because i thought if people saw me eating, they'd think i was fat, or gross. It was a stupid assumption, since everyone ate at lunch time. Near the end of the year i understood that, but still couldnt stop, becuase if one day i just randomly ate in class, people would stare. Not because its gross, because they all knew i hated eating infront of people and it would be a big deal.
Don't worry about whatever your peers think. It was a stupid idea, and i understand now. It's not worth it.
its ok to sit alone. it shows youre independant enough not to care what ppl think. its NOT ok to eat in the bathroom.. you have the same rights as everyone else. take a breath, smile, and sit alone. then go to the library :p thats what I do when all my friends go home for lunch :) ooooorr you could go sit with someone and be brave? :)