I've lost around 30 pounds since February by eating lean protein (and sometimes whatever I want), fresh fruit and vegetables. I've been hovering at 200 for the last month, but am getting ready for another push to lose 15 more pounds. You can use one day a week to treat yourself to one meal a week of whatever you want. You'll find you can't eat it all after a couple of weeks, but you will be satisfied and not feel so cheated. Also, it helps when you have friends over or attend an event. It takes the guilt away.
I wish you good luck on your program and hope you find something that works for you. Keep in mind, if what you do now is not sustainable; you'll pile the pounds right back on. For the long run, try to find a plan that you can live with and will be a lifestyle, rather than a diet. Diets don't work.
When we want a metabolic boost, there is a great recipe floating around out there that is called the "Cabbage Soup Diet". It is endorsed by the American Heart Association and is one of the most adaptable I've found. It has a base of low sodium chicken broth and of course the veggies. You can make every meal different by adding new ingredients each time you prepare it. I make up a two gallon pot of the cabbage, tomatoes and celery, then add zucchini squash or broccoli or other non starchy veggies for different meals. You can also add hot sauce or other spices to keep it interesting. The key is to minimise the starchy foods. You can have a half a cup of potatoes, brown rice or pasta; but not with every meal. Just once a day.
http://www.aboutcabbagesoupdiet.com/This approximates what we've done at home. We've only gone the complete course of this diet once, but find it very useful when trying to loose a lot in a few days. Most important, you'll still want to moderate what you eat after this contest; provided you want to keep the weight off. So, lean protein including; beef, pork, fish, chicken are all good. Restricting the white foods like rice, potatoes and pastas to a minimal level will assure continued results. So, you'll not have to deny yourself, because there are some great meals with those ingredients. Just a little more prep time for the fresh stuff. The quick frozen veggies are very good too. We usually only do up to five days on this program, just to get a kick-start.
By the way: Another way to approach this kind of contest is to go by percentage of body-weight lost. That way, no matter how large or small, it's based on percentages rather than pounds lost.
Good luck and hope this helped!