The diet that works for cookie monsters, who can resist anything except really good cookies. It's very simple. Eat only cookies in December. The rest of the year you won't want to see anything resembling a cookie. You will probaby gain about 5 pound in December but lose 10 over the rest of the year. It really works, I kid you not.
Disclaimer: If you're more of a potato chip or salty snack monster, this diet obviously won't work for you. Sorry.