I went from 100kgs (around ~220 pounds) to 70kgs (~150) in the space of 3 months. I didn't change what I ate whatsoever (My average day involves at least one meat pie & a considerable amount of chicken).
The only thing I started doing is working out. 1 hour a day, 4 days a week, doing entirely weight training (my father in law was a body builder, so I took a lot of advice from him, but a trainer should be able to get you on to a similar routine).
I'll admit that i'm not fit, I sometimes puff making it up the stairs to the gym, but physically I look awesome and am quite strong. Sport and cardio is good, but if you want to drop weight fast, lifting weight is the way to go. None of this Low Weight/High rep crap either, that will actually make you bigger, not smaller. I'm not up on the whole technical side of things, but those low-weight reps will result in big puffy muscles (that's why bodybuilders do it), Higher weights will increase muscle density but not so much size, and that's the kind of muscle building that burns calories.
It could just be me and not work for most, but my wife moved to a very similar routine to mine and dropped a lot of weight as well as putting on what I consider a sexy level of muscle.