Cons: Colonic irrigations done improperly can seriously injure the large intestine, so avoid them, says Grotto. Even “safer” plans (those that promote eating only select, nutritious foods) may cause fatigue or dizziness if they don’t supply adequate calories. If severe calorie restriction is sustained for more than a few days, the body may sense impending starvation and release stress hormones that cause fat stores to break down rapidly—a response that, ironically, may increase circulating toxins. “When fat is metabolized very quickly, the process may free up toxins at a rate that overwhelms the body’s capacity for dealing with them,” says Peter Pressman, M.D., an internal-medicine specialist at Cedars-Sinai Medical Center in Los Angeles. Finally, the enhanced energy that detox dieters often report may be the result of surging stress hormones too. (Evolutionarily, it makes sense: a “fight or flight” response drives hungry animals to seek out food aggressively.) An adrenaline-charged drive is short-lived, and with prolonged calorie restriction, the body powers down to conserve energy, ultimately slowing the metabolism.
Our Verdict: If you’re a healthy adult, living on vegetables and water for a few days isn’t likely to do you harm—or much good. “People who operate on the mode of ‘live today, detox tomorrow’ are fooling themselves,” says Grotto. Optimizing your body’s natural detoxification systems, he says, is best achieved by consistently practicing healthy behaviors: consuming nutrient-rich foods, drinking plenty of fluids, getting adequate sleep and exercising regularly.