The Master Cleanse system has been around for many years but success varies greatly on your genetics. Because it's liquid only you don't have a lot of energy to exercise. Also the detox part of it can cause flu like symptoms, diarrhea, constipation, and general aches and pains so the liquid only portion isn't really the biggest hurdle.
Yes, many people have tried the master cleanse which is a ten days diet. It is also called lemonade diet or the cayenne pepper. It works differently for different people. It has been said to be tough but it works for the majority who do it without stopping.