As bleak as fastcoach's response may seem, I would have to agree.
From personal experience I know it is possible to loss vast amounts quickly, but there is alot of research and realistic planning that need to be in place first. You have to prep your mind and body for it.
For example if you cold turkey from a 1800 cal a day lifestyle to a fast of 0-200 cal you have to know your body is not going to like that.
there is a price to be paid for the pounds lost.
Metobolic rate change
bowel disorders (bacterial imbalances)
You have to be aware or these things and know how you are going to deal with one or all of them.
Research. Curezone is a wonderful tool for information.
Good luck to you with meeting your goals. Both short and long term.