It's a good thing that you didn't choose some drugs.
It is suggested to change the method first and step by step. Extend some cycles, from three days to three weeks, but not just drinking water. Plan implementation. First of all, you can eat fewer meals, such as some snacks, such as potato chips and chocolate. Striving for a vegetarian diet for three weeks can reduce your digestive burden. Three weeks is also reasonable, and there is plenty of time to adapt. Avoid bringing discomfort to the body. Eating more fruits and vegetables will help to eliminate the garbage in the body, strengthen the metabolic rate and ensure the nutrition needed every day. Fruits and vegetables are rich in fiber and can help you clean your intestines. Try not to eat meat or food in the meantime. You can do it once every quarter. Believe in your body, you will be healthy and in excellent condition. You can also choose the juicing method and eat as many fruits and vegetables as possible. These are all natural green nutrients.
You are torturing yourself by saying that you only drink water for three days, unless you really want to experience it, but it is not recommended for you at present.
I hope I can help you. If you have any other questions, please contact me.