It helps draw more toxins out as the fat is metabolized. Trying to increase glutathione levels is helpful for removing toxins from the body. There are a number of tests like the Ion Panel Test and Mycotoxin tests that require preparation like this to identify metal and mold levels. Generally dry fasting 12 - 16 hours is a good start. Muslims do this during Ramadan and have for a long time. While lacking a microscopic perspective, I suspect that most of them feel better.