It is a detox method recommended by the practitioners of alternative medicine to flush out toxins from the body. The ingredients include two glasses of organic apple juice every two hour for two days and eating only fruits and vegetables. There are many such recipes which are followed.
As a practitioner of modern medicine, I normally don't recommend them because I am not sure of usefulness . But I am not averse to them since the anti-oxidant contents of fruits and vegetables is very beneficial apart from their other benefits.
I will like to mention here that I have been following a diet regimen in which I consume fresh fruits in the breakfast and dinner on Mondays and Thursdays. I also take some nuts and milk along with them. I have been following this regimen for so many years. I find this regimen very conducive to my health.
I have heard that such detox diets may have some undesirable effects too but I am not sure about them. I think that the undesirable effects may include nausea, vomiting, diarrhea or abdominal cramps.