Stick your finger down your thoat, gag yourself with your tounge (dont recomend you could choke on it), or the toothebrush trick, I used to do all of the above.
THAT SAID DON'T DO IT! ITS NOT WORTH THE PHYSICAL AND EMOTIONAL PROBLEMS ATTACHED WITH IT!!!
Trust me if you think your depressed now wait until the weight comes off and then you gain the littlest bit back, you will be devestated.
If your depressed go to a therapist, they can help you with your depression without giving you any sort of drugs (unless you need them then they send you to a psychiatrist) and are covered by most insurance companies.
Even if you eat alot you can still be in shape by working out. There is no reason anyone can't work out unless you have a disabillity.
I'm a real big guy (6'3 320) who used to make himself puke and it did nothing but make my depression worse and make me paranoid that people were talking about me.
I wasn't always this big,I was recently put on medication that made me blow up :-[ , but after getting some help my depression is now under control.
Even though I'm big I'm in some what in shape, I'm a professional wrestler who played two varsity sports in high school (lacrosse and football) and never used my size as an excuse to not work out.
My advice is just work out and if you feel like you must eat alot eat a few small meals throughout the day. Mentally you will feel like your eating what you used to, but it will be spread out evenly (most of the wrestlers that I know do this they eat around 5-8 small protien enriched meals a day and it keeps them in amazing shape.
Sorry I know you didn't want to hear that but as a fat kid I felt I had to give some advice.