My personal opinion (sadly based on many years of experience), is that diets don't work because they are, by design, temporary. There is a start date and when/if you get to your goal, there is an end date. Once you reach that end date, MOST people go back to what they know and the way they used to eat. They gain the weight back (and then some!) and the cycle starts all over again! As Janie1234 said, the worst is when you feel deprived on a diet, you will normally wind up overeating on whatever it was you felt you were missing.
Good luck Karen! Let us know if you discover the "Holy Grail" formula!
Carrie