While I tend to agree with Feo, Lualu, and Marie, in the first year of NB I did juice quite often. Even against the wishes of my practitioner. My liver just seemed to be snoozing most of the time and I felt like the carrot juice really helped me. Maybe it helped me because I was deficient in something in the juice, I'm not sure. I only did it every other day for six months or so, and I don't do it anymore. I've never been one who's had problems tolerating lots of carbohydrate so I think it can also be an individual thing.
Dr. Wilson does recommend carrot juice and a little bit of wheat grass juice and he's been at this for thirty years, so I wouldn't be worried too much if you feel like it could help you. As long as one isn't diabetic, I think it would be okay for a certain amount of time.
It is a bit unnatural, but I think sometimes the benefits out weigh the risks. Also I think Paulette made some good points.