Juice detox diets can be tempting -- they promise quick weight loss, and drinking nothing but fresh fruit and vegetable juice sounds like a healthy way to do it. Nobody will argue the value of fruits and vegetables in your diet, but juice detox programs have dubious value. The weight loss claims are usually exaggerated, and even if they aren't, weight loss at that rate leaves you at risk for gallstones. A healthier and more permanent method is to incorporate fresh produce into a reduced-calorie diet and lose weight on the slow-but-steady plan.
Juice detox programs vary, but most involve consuming nothing but fresh fruit and vegetable juice for a period of seven to 10 days. Programs vary even within this parameter, with some programs allowing unlimited juice consumption, while others strictly specify how much of each juice to drink and when to drink it. While increasing your consumption of fresh fruits and vegetables -- even in liquid form -- is a boon to your health, juice detox diets generally don't lead to real weight loss, and detoxing is usually unnecessary anyway.
Your body has a natural, built-in detox system -- your liver and kidneys. These organs clean toxins from your body so they can be excreted in your stool and urine. If they are properly functioning and intact, they do the job just fine and need no assistance. Juice detox programs do flush out your body, but in a different way -- the large influx of fluid has a diuretic effect, and you'll urinate more. The high fiber content of the fruit and vegetables will stimulate your bowels, and you'll have more frequent bowel movements. This combination of fluid loss and increased bowel motility may indeed make you lose a couple of pounds, but it won't be from fat. The lost weight is simply the result of lost water and lean muscle, and you'll regain most of it when you begin eating normally again.
Fat loss occurs when you burn more calories than you consume, no matter where those calories come from. Carbohydrates are your body's primary fuel source because they're easy to burn -- stored fat is much harder to burn on demand, so it usually takes time to burn it off. Juice is almost entirely carbohydrates, which means your body will have a constant influx of energy, and unless that energy is needed, it can be stored as fat as easily as any other food. Most juice detox programs are very low-calorie, but the ones that allow unlimited juice consumption can still provide more calories than you need -- some juices can have 100 calories or more per cup. If that's all you're allowed to have, theoretically, you could still consume more calories than you need if you quench every hunger pang with a big glass of juice.
If your juice detox program limits you to a very low calorie consumption, you are at risk for low blood sugar, which can cause headache, nervousness and fatigue. In severe cases, you may experience dizziness, hallucinations or seizures. The "flushing" effect of the juice can leave you dehydrated, and the sudden increase in fiber consumption can cause bloating, gas and abdominal pain. You're better off using exercise and a sensible eating plan to lose weight, but don't discount the fruits and vegetables. Eat them whole instead of juicing them, and you'll get the full fiber benefit and fill your belly at the same time.