Elizabeth Preston analyzes claims of the popular liquid diet:
Apparently, a body that’s becoming healthier looks a lot like one that’s unwell. Symptoms of detox may include fatigue, headaches, nausea, hives, decreased bowel movements, increased bowel movements, strangely colored bowel movements (“Did you just drink some of our beet juice?”), dry mouth, runny nose, and canker sores. I should ignore those symptoms, drink herbal tea, and be reassured that I’ll soon be skinnier. Sorry, healthier.
The science doesn’t hold up:
[Y]our body does its own cleansing via your kidneys and liver. The wastes and unwanted materials those organs filter out leave you via the toilet—not through your sweat glands or the soles of your feet or water blasted up your colon. And depriving yourself of calories doesn’t make the process go any faster. If anything, it’s the opposite, because fasting slows your metabolism.