Just weighing in to say good luck to all contestants. Do this smartly, not too fast, and you'll all be winners. I lost over 40lbs in the past year and a half (lost them during one year and been maintaining for half a year now). Going back on a diet now, I want to shed those final extra 20lbs too.
What worked for me is the GI (glycemic index) diet. It is probably especially effective for people with a lot of excess weight, because most people who are obese are also insulin-intolerant. If anyone's interested, I can post the basic principles here.
Another thing that works for me is exercise. I work out 3-4 times a week, rain or shine. Bought myself a gym subscription and been using it religiously. I actually enjoy the break in my daily routine and look forward to it. Now, I'm your typical couch potato by nature, the one that always tried to avoid PE in any possible way, but in this decade I discovered the actual joys of exercise, and more specifically running. I couldn't really run when I started losing weight, but very very gradually, I moved from walking to running (doing just slightly more running every week). I'm still not a very good runner
and I'm up to about 4k of running at a time (I add 3 km walking), but it feels sooooo good! I can't wait for my next run, they truly are addictive. I never in my life thought I would be able to run more than 200 meters, but here I am jogging away, so I can honestly say, it is for everyone. Just do it gradually and read up about it before you start to avoid injury.
Again, best of luck to everyone!