Because… Juice fasts and restrictive diets can make you lose muscle because such plans are low in protein—the key nutrient for muscle building and maintenance. Because muscle is calorie-burning tissue, you can end up with a slower metabolism, or calorie-burning capacity, meaning you'll be more prone to weight gain than you were before. On top of that, you'll likely feel hungry and tired without sufficient protein to help stabilize your blood sugar and tame your appetite. No wonder extreme diets almost always fail in the long term.
And Ian K. Smith, M.D. agrees. Dr. Ian is a Harvard graduate, founder of the SHRED Lifestyle, and the author several best-selling diet books. He explains that the liver, kidney, lungs, skin, and gastrointestinal system remove toxins that accumulate in the body. But following a detox diet full of natural foods can enhance the body's ability to cleanse. He adds, however, that dieters should make no assumptions about health when choosing a detox diet. "Detoxes have gotten very trendy, and many of them are unhealthy and quite dangerous."