Hi Jano, welcome to the SB BOARDS.
In a nutshell, SB is loosely based on the GLYCEMIC INDEX. The one site I refer many people to in helping explain a bit better in detail is below:
http://www.prettyimpressivestuff.com/sugarbusters
You can find this book just about anywhere, and another book I recommend to those interested is by Michael Montignac called EAT YOURSELF SLIM, as he's the one who wrote a book about this WOE first and SB took his ideas and made a US version after that.
Also, SB is a very healthy WOE, and one you could follow the rest of your life. It is NOT a low-carb diet as many, so some unknown reason thinks it is.
Don't be afraid to ask questions, we'd be happy to help!
GOOD LUCK!
Debbie