I too am over weight (obese) according to the doctors... 117kg. I was at the last straw and decided to try a nautropath, it was the best thing I've ever done. She put me on a detox for weeks (don't think this is easy, you've got to want to do it). I finished that 1 week ago and had lost 5kg, although that was not the purpose of the detox, it was mainly to get the body and it's organs prepared and working how they should. I am now on the weight management program and have lost in 1 week another 2 kg. I feel fantastic, I have heaps of energy and am walking 1.2 km per day. Prior to this I was a couch potato, I was a size 24 and not being able to exercise because I was so big. It was an excuse of course and I just didn't have the energy. I would highly recommend seeing a nautropath.
Have you tried weight watchers? That has been a success for many people. Also, cut out all soda, and drink more water. Try eating multiple small, healthy meals a day instead of just 3 meals a day. That gives your body a better chance for keeping a good metabolism. Also, make sure to switch up your exercises between cardiovascular fitness and weight training.