i looked at your profile, and heres some quick advice:
When a was a personal trainer, I had clients with your body type. I would honestly say that you should give yourself a year to reach your goals (and Im just assuming what they may be, I dont know for sure), which is relatively quick, considering how many years it took to get to where you are at right now. (Which, BTW, is not as bad as you think it is.)
I don't know what your personal goals are, but remember, its not about weight, its about how you feel about how you look.
I would say go for a weight loss of roughly 6lbs per month for about 6 months, then forget worrying about weight. That'll knock off 30-40lbs, which would be great. Then concentrate on LOOKING better instead of the scale. Screw the scale.
Watch your nutrition, exercise regularly, and keep a journal. I would even advise you to take a picture of yourself in your skivvies once a month so you have something to compare it to.
Again, most important thing to remember is that its a lifestyle change. Diets don't work, you have to be 100% committed, even when you have a bad month. Your body isn't gonna be thrilled right away with the change, and is gonna put up a fight, but will thank you later.
Remember everyday that you exercise and watch your nutrition is a day you can go to bed happy knowing you did something to get to your goals.