To Juice Or Not To Juice?

I used to really crush juice cleanses. For three days when we’d do this giant collective effort at my office (usually around this time of year, bathing suit season just around the corner). And everyone would be complaining and starving and all “ughhh I feel so miserable” and I felt totally and completely fine. I never actually lost any weight, and they weren’t fun, and they cost me half my paycheck… but I felt fine.

The problem, however, arrived on Saturday post juice cleanse, when I’d go out with my friends like a normal non-juice-cleansing human and have two cocktails. Then a few more. Maybe one more. Then a few hours later I’d find myself eating handfuls of shredded cheese straight from the bag over the kitchen sink. Cleanse = blown. Then I’d give up any attempt at cleansing and or whatever I was into at that point, because why bother? “I’ll just start something different on Monday.” Rinse and repeat.

Are we at the point, collectively, that we can all agree juice cleanses are a crock of shit? I’m not sure. But what I do know, is that there’s some straight up scientific evidence pointing to the negatives of juicing. And who better to break it down for us, than a registered dietitian and functional medicine nutritionist?

Meet our friend, Megan. You’ll soon get to know her a lot better on our pod when the episode airs, but for now she’s gonna jam on a topic that’s pretty hot around this time of year. You know, all that “Spring cleaning the body” messaging. Take it away, Meg!

To Juice or Not to Juice?

Our culture has normalized extreme eating, advertising the need for juice cleanses to “detoxify” or “re-set” the body. Although fresh juices can be a wonderful addition to a balanced diet, the body was not designed to thrive on juice alone. You may be surprised to hear that going on a hiatus from solid foods is not the best method to promote natural detoxification!

1. What is juicing?

Juicing extracts the liquid from fresh fruits or vegetables, which contains much of the vitamins, minerals, and phytonutrients (“phyto”=plant). The process strips away all of the fibrous, solid matter.

2. What are the differences between juices and smoothies?


  • extract liquid from fruits & vegetables
  • lack fiber
  • provide quick absorption of energy


  • blend whole, intact fruits & vegetables
  • contain fiber
  • provide slower absorption of energy & increased satiety

3. Why is fiber important?

Fiber is a central component of a healthy diet! It is a type of carbohydrate that is not broken down by the gut, so it does not contribute any calories to your meals. Fiber provides roughage to cleanse the digestive tract, slows the absorption of sugar into the blood stream, and helps increase your level of fullness.

It is naturally present in whole grains, beans, legumes, and whole fruits & vegetables. For example: 1 cup of chopped, raw carrots contains ~3.6 grams of fiber, but 1 cup of carrot juice does not contain any. Most consume a diet that is below the recommended dietary allowance (RDA) for fiber:

  • Women: 25 grams/day (19-50 years old), 28 grams/day (during pregnancy), 21 grams/day (>50 years old)
  • Men: 38 grams/day (19-50 years old), 31 grams/day (>50 years old)

4. Does the body absorb more nutrients from fruits and vegetables if you juice them rather than eat them in their whole form?

By stripping away the fiber, the body absorbs the energy from juice more rapidly than it does from whole fruits and vegetables. However, there is no substantial evidence to support that the body absorbs more nutrients from juice rather than a whole fruit or vegetable.

5. Does a juice cleanse really work to detoxify your body?

Juice cleanses provide a break for the digestive system, which can become bogged down by overconsumption of processed food. But, despite popular opinion, juice cleanses do not eliminate toxins that are already present in the body. In order to release the toxins stored in your tissues and fat cells, you need a combination of antioxidants, amino acids (building blocks of proteins), and fiber.

The liver is our most important organ of detoxification. Through 2 pathways, the liver works to remove toxic compounds circulating inside of the body.

  • Phase 1: Toxic chemicals & heavy metals (from air pollution, plant pesticides / insecticides, chemically-treated water, medications, cosmetics etc.) are broken down through a series of chemical reactions.
    • Required Nutrients: B vitamins, folic acid, magnesium, iron, glutathione, antioxidants.
  • Phase 2: Converts fat-soluble compounds to water-soluble compounds to allow for excretion through urine or bile.
    • Required Nutrients: amino acids, sulphurated phytochemicals (e.g. cruciferous vegetables, garlic).

Without protein and fiber, the liver is unable to complete phase 2 of its detoxification pathway. When your intake is restricted to juice, the body is not provided with all of the nutrients it needs to support liver function, so the natural detoxification pathways are actually inhibited rather than enhanced!

6. Are there specific times during which juice fasts may be necessary?

Although fiber is important for the general population, there are times when it is necessary to eliminate roughage from the digestive tract. When I work with patients who have a high level of inflammation in their gut (this could be due to Crohn’s, Ulcerative Colitis, diverticulitis, etc.) they are typically restricted to a “clear liquid” diet, or juice fast, for a short period of time to allow the bowel to rest and recover. During this time, I work with patients to add special liquid protein sources so that they do not become nutritionally deficient. Even in these cases, the goal is to eventually reintroduce fiber to promote long-lasting gut health.

7. Is there a food safety hazard to juicing?

Actually, the answer is yes. Unpasteurized juices can contain harmful bacteria. If you choose to juice, I recommend choosing organic produce to eliminate pesticides and toxins present on conventionally grown fruits and vegetables. It is also important to consume fresh juice within 48hrs of preparation (preferably the same day!), as bacteria can grow if the juice sits out for too long. Be sure to thoroughly wash the juicer with soap and water after each use.

Final notes:

Remember that when you drink a juice you are not consuming a whole food, the fruits and vegetables grown in nature have been processed and stripped of their fiber. Try to choose produce in its whole form whenever possible, as this will help promote balanced blood sugar levels and increase your level of satiety. Eat a variety of both raw and cooked fruits and vegetables to optimize your nutrient intake.

The caveat is that if you have a difficult time consuming whole fruits & vegetables (particularly greens), juicing can be a great way to add fresh produce to your diet. I know that a message of moderation is not one that the extreme dieter wants to hear, but juice is best consumed in the context of a balanced diet complete with protein, whole grains, and fat. Remember that fiber and protein are vital for the liver to detoxify your body and are completely lacking in juice.

About Megan Fahey

Megan is a Registered Dietitian and Functional Medicine Nutritionist specializing in eating disorders. She completed her Masters of Science in Nutrition and Dietetics at Bastyr University in Seattle, WA, one of the country’s leading schools of integrative medicine. Megan is an active member of the Academy of Nutrition and Dietetics (AND), the Integrative and Functional Nutrition Academy (IFNA), and the International Federation of Eating Disorder Dietitians (IFEDD).
Megan Fahey RD, PLLC, is her private nutrition practice, founded to help clients heal their relationships with food through nutrition intervention and psychological exploration. Megan offers programs in Westchester and Fairfield Counties, traveling to work with you and your family in the comfort of your own kitchen. She is a certified Health at Every Size® Facilitator and have extensive experience developing and implementing detailed nutrition care plans.
In addition to seeing private clients, Megan works at Monte Nido & Affiliates in residential eating disorder treatment for adolescents. Prior to her current position, she held the role of Clinical Dietitian Specialist at Western Connecticut Health Network. Visit Megan’s website, and connect with her on Instagram and Facebook.

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