This topic has come up many times and the answer really is that it is not healthy and not a good practice.
Here is a thread that covers the topic:
Master Cleanse/Lemonade Diet/etc
Suzanne wrapped up that thread nicely with the following:
The details of that diet scare me.
Feeling the effects of malnourishment are certainly not signs the body is being cleansed. It means you are doing something wrong.
There's no such thing as mucoid plaque. The term was created by an herbalist that wanted to sell his colon cleansers, after he went into the forest for a few weeks and came out with a vision. (At least that's how he claims it came to him) It's man-made hype. Ask any gastroenterologist and they'll tell you they've never seen "mucoid plaque" and they've actually been in there Go here to read more http://en.wikipedia.org/wiki/Mucoid_plaque
The biggest medical experts out there agree that the body naturally cleanses itself as long as you eat a healthy diet. The body does not accumulate toxins (myth), and does not need detoxing. Get 35 grams of fiber (preferably from food, not supplements) and drink 8 glasses of water daily, and that's all your body needs. Someone designed our bodies very well
Since the original post in this thread has been answered, and since we do not provide support for this type of unhealthy practice, I'm going to close this thread. I hope I don't offend anyone in particular. It's just the nature of the internet to create buzz around fad diets, which makes them believable to many. But that doesn't make them safe, healthy, or make their claims true.
I am going to close this thread because we cannot support unhealthy practices like master cleanse.