This is something from Jason Ferrugias Blog:
Low carb diets suck for gaining muscle - No matter what anyone may tell you, you need carbs to grow, there is no way around it. I took some bad advice years ago and tried desperately to gain size on a no carb diet and I got nowhere. I had even tried this approach with clients and they experienced similar results. As soon as I brought the carbs back, I started growing again as did all of my clients. Sure there are different levels of insulin sensitivity and some people tolerate carbs better than others but the bottom line is you need some carbs to grow.
This may only be 100 grams per day on non training days and 250 grams on training days or it may be 300 grams on off days and 600 grams on training days. That is highly individual and is something you need to experiment with to find out what works best for you. I will say this though, the fatter you are the less carbs you can tolerate. If you are above 15% bodyfat you need to be very careful with carb consumption and need to limit the times you eat carbs to post workout and breakfast.
Another guy who seesm to know his stuff is Justin Harris. Here is a link to a page of his log where he talks about carbcycling:
http://asp.elitefts.com/qa/training-...=53491&tid=139
They recentlly had an interview with him on t-nation.
Basically carbcycling works by eating more carbs on your weightlifting days and less on your off days where you should also do your cardio. How much on ondays and how much on offdays is something you have to find out by yourself as it is very individual.