I asked this question a few months ago in the Master Cleanse Forum and a woman answered me and said that all of her celulite dissappeared after 20 or 21 days on the MC. I've only done the Master-Cleanse for 7 and 10 days, but during those cleanses I noticed a reduction in cellulite. I'm sure that you'll lose some, and not gain any. Anyway... I hope more people answer your post this time, I'm really curious too.

I am responding to an old post, but if anyone is searching for an answer to the cellulite problem by fasting, here is some encouragement. I just finished a Water Fast of 11 days. It was great. During the hardest part of the fast when I felt tired and did not feel very well--this was when my body was doing the most cleansing and healing--I was able to be at a friend's house completely alone. I was able to really rest, and allow my body to do its work. I was there for 5 days. I started out 30% bodyfat, 30lbs overweight and with a few health complaints. Among them were very upset digestion, bloating, a shot nervous system, a heart that seemed to pound in my chest constantly, and CELLULITE. This is after baby #5, who is now 2. On the sixth day of the fast I noticed that my legs (about covered with cellulite) were sort of slightly swollen or welt-like over all the areas of cellulite. These areas were also tender to touch and hot. Well, it seemed as though my body had turned its attention to all those hardened fatty-deposited areas and was clearing it out quickly! I was right, 'cause over the next week the cellulite has nearly gone. On day 7 my energy picked back up because it seemed that most of my healing issues had been taken care of. I continued to fast until day 11 and broke the fast. I had lost a solid 10 lbs. Now my legs are basicly smooth--the hardened cellulite is gone, my legs feel light and refreshed, including my gluteus, which was also afflicted with the horrible stuff. I am so happy with the results! Now I am continuing to exercise, including running which feels great since my fat is not bouncing around on me, and my joints feel great of course from the fast cleaning me out.
Bottom line is if you let your body rest your fast will work better and quicker. I would have fasted longer but I had to get back to mothering. I will fast again in about six months when I can arrange to rest during the fast. It's so productive! Your body will cleanse and heal when you fast, according to its own priorities.
Prior to my fast I had done 2 Hulda Clark style Liver Cleanses ( I do a much more simplified version) and they were super effective. I could tell they worked because before doing them I tried to take milk thistle and had miserable cold symptoms, so I quit taking the herb. After one Hulda Clark style cleanse I was able to take milk thistle no problem! I also did 3 months on the Colonix (Dr Natura) and Toxinout, to cleanse while I waited for my fasting date. I think this helped my fast to work better and faster and be more comfortable. Awesome! I am so happy! So is my husband! I recommend reading the book Fasting Can Save Your Life by Herbert M Shelton . It was so encouraging and enlightening when I was fasting. Can be ordered at healthscience.org. Happy fasting.