Hiding it from others; A few more tips

Don't raise suspicions with anyone. Don't call yourself fat in front of others.
Go to the kitchen often, even just to get water and sit it there for a few minutes if no one else is in there. It will seem suspicious if you don't go in there often. (My parents say that's the only reason they know "know" I eat, cause I go back a forth a few times between lunch and dinner. I only get water or a small snack sometimes though:)
If people do start to ask questions, the worst thing to do is get angry. They will say you are being defensive and then it is obvious you are hiding something.
Do you share a computer with someone? Delete the history often!
If you do happen to purge, do so when people are still at the table or eating together. If you run water right after you eat, it becomes obvious. The rest of the time at the table just say you are full.
Another If You Purge tip, wear a glove and hold it on with the other hand so you don't swallow it. This prevents those burns on your hands that you can get.
Wearing make-up when you are in front of others is a good idea if you are starting to get pale.
Don't wear Too baggy of clothes, it becomes a bit obvious. wear between "these fit great" and "these are way too big"
Black is slimming but also bad in this case. wear brighter colors if you are up for it. Brighter colors make people think you are really happy and also they aren't as slimming and can distract people from noticing your ever shrinking body.
DOCTOR! Drink a ton of water ( I suggest Smartwater because it adds electrolytes) before you go in or a lot of water and a Gatorade. only 50 calories for a Gatorade.
If you can afford it, go for a tanning membership and go once or twice a week. Even if you are pale, you won't be for long. Most memberships cost around 30 dollars a month though.