Juice Fasts: A Quick Path to Better Nutrition or a Potentially Risky Fad?

People who sell ready-made juice cleanse products and high-powered juicers – and those who spend their money on them – claim that drinking nothing but juice for a few days can lead to weight loss, detoxification, and a number of other health benefits.

A documentary released a few years ago centered on a morbidly obese man who went on a 60-day juice fast and allegedly became much healthier and even reduced the symptoms of his autoimmune disease. The movie brought juice fasts into the mainstream, for people of all health conditions and backgrounds.

Unfortunately, though, this is where things get dangerous. While adding extra vegetable juice to your diet is probably not going to hurt you, you also need to eat a well-balanced diet to ensure you get the fiber you need to keep your digestive system working properly and to prevent other medical concerns.

Problems with Juicing

Juice fasts ask you to drink a lot of juice and forgo other foods for the duration of the fast. The typical juice fast has you drinking 16 ounces of pre-made or home-pressed juices up to four times a day – meaning you might drink 64 ounces of juice or even more each day during a fast.

Under the most recent Dietary Guidelines for Americans, teens should have no more than 355 mL, or 12 ounces, of 100 percent fruit juice daily. This is meant to supplement a diet rich in whole fruits and vegetables. While there is no recommended amount of juice approved for adults, 12 ounces is a good target. It is enough to help you reach some of your vitamin goals without causing issues for most people.

The problem with drinking so much juice stems from the fact that juiced fruits and vegetables lack protein, healthy fats, and, most importantly, fiber. Fiber plays a number of key roles in the body, including helping keep your gastrointestinal system running smoothly.

When you take the fiber out of fruits and vegetables, you can eat a lot more of them. This means your intake of the vitamins in these foods also increases. You may think “More vitamins! Great!” but more is not always better. For example, greens are high in vitamin K, which interacts with the blood thinner warfarin.

Another issue is that, in addition to getting more vitamins, you also get significantly more sugar. Juices made with fruits have a lot of fructose and little fiber to help keep your blood sugar steady. This can cause spikes and crashes, as well as lead to an increase in triglycerides.

If you have any preexisting health conditions, it is important to talk to your doctor about adding juicing to your diet. If you plan to use juices in place of a meal on a regular basis, you should talk about your plan with your doctor or a registered dietitian even if you are healthy.

The Juice Fast Myth

The proponents of juice fasting claim a cleansing effect, leaving you feeling thinner and detoxed after consuming only juice for three to ten days – or even longer. They claim drinking only juice gives your body a break from having to digest meat, grains, and whole foods.

However, this claim is not based in what we know about the body and what we see regularly in our colon and rectal surgery practice. In reality, fiber helps your body digest everything you eat. It keeps your bowels moving, and keeps you regular. Your digestive system doesn’t need a break, and a juice fast is a quick way to cause yourself loose stools and other gastrointestinal issues.

When it comes to the detoxification claim, that’s also far from what modern medicine tells us about how the human body works. Your liver, kidneys, and intestines do an excellent job of filtering what you eat and drink, and your skin, nose, and lungs filter other things you’re exposed to. Your body detoxifies itself constantly through your bowel movements, urination, breath, sweat, and other functions, no matter if you are on a juice fast or not.

What to Do Instead of a Juice Fast

While having fruit and vegetable juice every once and a while isn’t bad for you and can even help you get some much-needed vitamins, it should be a part of a well-balanced diet. Eating whole fruits and vegetables every day is key in keeping your body working properly. A high fiber diet can prevent all types of gastrointestinal issues, from constipation to hemorrhoids, and even reduce your risk of colon cancer. We recommend trying to eat at least two fruits and four vegetables each day.

If you want to have 6 to 12 ounces of juice occasionally, it is unlikely to hurt you. However, don’t lose track of the fact that you could be drinking the equivalent of as many as four oranges in just a couple of minutes. With moderation in mind, juice can help you boost your vitamin intake on days when your diet hasn’t been the greatest.