Trade Your Diet For a Weight Loss Cure!

I am pushing 60 years old, been on a diet most of my adult life and have been over weight the entire time. I tried the Low Cal, Low Fat, Low Carb, the Zone Diets with little or no success. I even did the Optifast program where I don't eat for 3 months (I did lose about 60 pounds) but soon as I started eating my low fat diet the weight came right back. As I am getting older the excess weight is taking its toll on me and adversely affecting my health. I even have type 2 Diabetes now and faced with blindness, amputations, liver and kidney failure. What to do, what to do?