I did WW years ago, lost about 20Lbs then put it back on. I just couldn't curb the cravings, and although I lost weight I didn't really lose fat - I just lost "weight."
I usually recommend everyone read "Good Calories, Bad Calories." The author addresses a lot of issues, including why people don't end up losing that last bit of weight regardless of caloric intake or exercise. I bet you can find it at the library. I did.