But can fasting remove these? "Theoretically, yes," he says. "When fat is mobilized, anything that is fat-soluble should be mobilized, too -- should, that is," Dillard tells WebMD.
Although there are no studies of juice fasts/diets, water fasting does have some scientific evidence behind it -- "but very scant," admits Strychacz.
In the book Triumph Over Disease, Jack Goldstein, DPM, outlines his true story in overcoming ulcerative colitis by sticking to strict water fasting and a vegetarian diet. Goldstein is one of very few people who has tested his own tongue scrapings, urine, feces, even perspiration during a water fast, Strychacz says. "He found that the contents [during a fast] are different than normal -- that toxins like DDT do get removed."
Strychacz would like to conduct a study of fasting's effects on atherosclerosis. "Look at Dean Ornish's low-fat diet. He claims not only to arrest but actually reverse atherosclerosis. That's huge. I would argue that if a low-fat diet will reverse it, then what about a no-fat diet?"
Some still consider fasting -- in any form -- to be "out there." "When I review diets that are not based on science, the question I ask myself is: Would I feed them to my family? In this case, the answer is a clear no," says Susan Roberts, PhD, chief of the Energy Metabolism Laboratory at the Jean Mayer USDA Human Nutrition Research Center on Aging and a professor of nutrition at Tufts University in Boston.
But the psychological or spiritual effect can't be discounted, says Dillard. "People love the idea of cleansing, of purification rituals, going to the Ganges, to the spa. It has powerful psychological, religious, spiritual meaning. That has its own positive effect on health. But we need to separate that from saying this is science or good medicine."
Just don't look at water fasts or juice diets as a weight-loss solution. As with the Atkins diet, restricting carbohydrates causes you to lose weight -- but you'll gain it all back, says Dillard. "You're losing water in your system."
Juice diets do prevent your body from going into a state called ketosis, he says. Ketosis means your body has no carbohydrates to burn for energy, so it has to burn stored fat or whatever else is available, he tells WebMD. "You feel bad, even smell bad. That's what makes you feel like hell during a [water-only] fast. But is that because the toxins are coming out? No! You're going into ketosis. It's known physiology."