I like (so far anyway) using a hybrid Keto/Paleo diet... The keto allows me to eat higher fat, due to burning fat rather than carbs, but also limits how many carbs you can have a day if you want to stay in Ketosis... (30g carbs/day or so)
It's essentially the same a Paleo diet, just allows you more food options as long as you keep down the carbs.
Ketosis diets are the principles that the Atkins and South Beach diets are based upon. These diets, however, are made for relatively sedentary people who may do some light exercise here and there... However for bodybuilding it's important not to stay in this state indefinitely. Carb "refeeds" are a must...
Here is a good post on the subject, pretty straightforward and easy to understand
CKD - Cyclical Ketogenic Diet