I think it was back in the early 80's I did a 10 day water fast. Yes, that's right.....only water for 10 days.
I had read a book called "Help Lord, the Devil Wants Me Fat" by C. S. Lovett.
Our bodies truly are amazing. Similar to a submarine, that is made to operate using 2 different forms of energy, (one for when top side, and the other for when totally submerged) ...so are our bodies equipped to operate using 2 different forms of energy supply. Food burning process, or fat burning process. When the body has been deprived of all food for 3 days in a row, it automatically switches over to it's less potent energy, but none the less, sufficient fat burning process. When that happens, after the 3 days strictly on water, the body no longer hungers for food. BUT you have to have put absolutely nothing in your body that requires being processed through the digestive tract in order for the body to switch 100% over to the fat burning process. Even the slightest ingestion of any substance that requires digestion, then the fat burning process is ceased...and you would need to start over again.
Granted, the fat burning process provides less energy, and so this is not something you would want to do if your job requires physical strength.
I was a home maker at the time I did this and was able to allow my body the rest and relaxation it needed for this process.
This was a very spiritual time for me.
Lovett's book takes you through the whole process, explaining everything and how it works...and how to slowly bring yourself back into the food burning process. This is very important.
So for real cleansing, physical and spiritual, a complete water fast will do it.