Need Diet plan after Hysterectomy ?

I had a Hysterectomy 10 years ago and i am doing great. There are things to contend with but i do. and I am not sorry for one minute that i had it .The only question i have is how do you lose the weight i have tried diffrent diets but i still cant get passed the last 20 pounds .and before long i am right back where i was when i started the diet.I was a very thin person before and i cant understand why i cant lose the weight. Anyone have any sugestions?[/b]