diets would you consider extreme and unhealthy?

People that do only the one part of the master cleanse. i.e. distilled water, lemon juice, maple syrup, cayenne pepper. When they do it for more than 3 days, it can be very unhealthy since your body isn't getting minerals like sodium and potassium which are pretty much necessary for your heart to beat!!

I had a friend who did this for 10 days and he lost weight alright, he lost muscle!! He also had decreased brain function....