I did a 30 day and a 50 day juice fast and hope to go 60 to 75 days in my next one.
One one gets through the first few days, all hunger pretty much leaves and it is quite easy...easier for me than dieting certainly.
Both times I lost a lot of weight which I needed and interesting it did not seem to yoyo back on fully. For instance, I lost 60 pounds on one and though I did gain some back when went back to eating like I used to, gained 1/2 of it back over the course of the next ten years instead of gaining it all back plus more.
I had never in my life lost weight without gaining it ALL back and plus gaining some more so this is a big breakthrough as it seems to change the setpoint which is huge as far as weight loss. (setpoint theory = one always goes back to around the same weigh their setpoint is at despite what they eat).
I went on it for cancer (that did not return) but it also fixed my knee (note I was not just juice fating but doing Dr Richard Schulze 's whole incurables program plus more)l.
I had a torn meniscus cartilage in my knee they told me would never stop hurting without arthroscopic surgery which I had refused due to having several risk factor for future problems. I was not even thinking about my knee when on it so it was nice it seems to fix that too.
I think the fact that most of what is consumed is raw accounts for a lot of the healing and that it is going right to healing and repair unlike taking smoothies or juice with food or pulp.
Juice fasting with 100 % raw foods really helped Dave the raw food trucker heal colon cancer, kidney disease and long time diabetes as well as lose about 225 pounds. He has done long fasts up to 100 days maybe longer.
I posted some of his earlier videos here. I heard him speak in person not long ago and he is glowing and inspirational.