Water fasting under medical supervision is an excellent way to detox your body, but it does not work as a way to permanent weight loss. This is because when you do without food, your body switches into starvation mode... that's probably what kept our ancestors alive during times of famine. So the body protects itself by going into energy-conservation mode and therefore burns off even less fat than before the moment you start to eat again. Fasting for weight loss doesn't work, because the moment you eat again, you will put on weight, big time. It is also very dangerous to fast without food, hence the proviso that it should be always done ONLY on the advice and ongoing supervision of a qualified medical doctor. It is too easy to do your body permanent damage by fasting.