Does Juice Fasting Actually Work?

Juicing is promoted for everything from weight management to internal cleansing or "detoxing," but are there any real health benefits?

Embarking on a juice fast means consuming nothing but freshly made fruit and vegetable juices for a given period of time, usually anywhere from one to three days, though websites promoting seven-day, ten-day and even longer fasts can be found online.

Why do people go on juice fasts? The most common reasons people give include removing environmental toxins from the body, kick-starting a weight loss diet, or simply to break old eating habits and start anew. If you are thinking about fasting for one of these or any other reasons, consider the pros and cons.

The Advantages

With juicing, you can control and sometimes mask the flavor of healthy veggies you donít especially like by blending them with sweet and compatible fruits or berries and seasonings. You barely taste the kale or spinach when itís blended with banana, mango, and gingerroot.

Some people consider juicing a convenience because theyíre short on time or donít feel like preparing vegetables. But fresh fruits and veggies still need to be prepped for juicing, and your juicer or blender needs to be cleaned after each use, so convenience is questionable unless someone else is doing the juicing (and the cleaning up) for you.

The Pitfalls

"A glass of freshly made juice can be a great way to add nutritious fruits and vegetables to your diet," says Alissa Rumsey, a New York City-based registered dietitian and spokesperson for the Academy of Nutrition and Dietetics. "But itís not the nutritional equivalent of whole fruits and vegetables, and itís not a miracle food thatís going to make you skinny or cure whatever ails you."

As for claims about cleansing, most health experts agree that juicing won't rid your body of toxins. As Rumsey points out, your liver, kidney and digestive system do a good job of that, and under normal circumstances, they donít need any help.

It's also important to note that mechanical juicers separate fruit and vegetable fiber from the juice, and the fiber is usually discarded. That means you are missing out on the many benefits of whole-food fiber, which include blood sugar regulation, cholesterol reduction, and satiety, or a feeling of fullness after you eat. Satiety helps prevent overeating.

A meal of juiced fruits and vegetables also lacks balance. You're getting a rush of carbohydrates with little to no protein or fat, which can lead to a spike in blood sugar levels. Your body doesnít feel the same level of satisfaction from drinking a meal that it does from chewing and eating a balanced meal in normal stages. While youíre juicing, thereís a good chance youíll end up a lot hungrier than you would be if you ate the equivalent in whole fruits and veggies. As a weight loss plan, this is how juicing can backfire.

"After a couple of days of juice fasting, you may feel lighter or less bloated," Rumsey admits. "But thatís only because youíve lost a lot of water weight, as you would with any other calorie-controlled diet."

When the fast is over, she adds, most people revert back to their old eating habits, often eating even more food than usual to make up for what they craved on their self-imposed "cleanse." Thatís due to the lack of balance as well as calories, and one reason why itís better to eat some solid foods in the form of lean protein, whole grains, and healthy fat, along with a glass of juice.

Overall there donít appear to be many health benefits from drinking your daily dose of fruits and vegetables. And there is a small but very real chance that juicing can make you sick, especially if taken to an extreme. Juicing provides you with very concentrated amounts of nutrients and other substances found in fruits and vegetables, and in one documented case, a man who juice fasted for six weeks ended up hospitalized with temporary loss of kidney function. This was because he regularly consumed large amounts of concentrated oxalates, substances found in spinach and other leafy greens, beets, berries and other foods that can be toxic to the kidneys when consumed in large quantities. The man later regained just partial kidney function.

Getting Your Juice On

If juicing appeals, consider pureeing fruits and vegetables in a blender, rather than using a juicer. This way, you'll maintain the fiber and you'll have the option of creating a healthier balance of nutrients by adding fats and proteins such as nuts, nut butters, avocados, seeds, tofu, yogurt or non-dairy milks such as coconut or almond milk. If added ingredients make your juice-like drink too thick, you can always dilute it with water.

"A day-long cleanse isnít likely to hurt you," Rumsey assures. "But the best way to 'eat clean' is to rely on whole fruits and vegetables in their natural forms, pair them with other whole foods, and avoid processed, sugary, and salty foods."

Alissa Rumsey RD, CDN, CNSC, CSCS, reviewed this article.


Rumsey, Alissa RD, CDN, CNSC, CSCS. Email to author, November 19, 2015.

Getting JE, Gregoire JR, Phul A, Kasten MJ. "Oxalate Nephropathy Due to ĎJuicingí: Case Report and Review." Amer J Med. September 2013;126(9):768-772.

Yeong-Hau H. Lien. "Juicing Is not all Juicy." The American Journal of Medicine. September 2013;126(9):755-756.