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Juice fasts have been popular for decades, with various trends coming and going, and sometimes staying. But is juice fasting good for you? This article examines 3 popularly touted juice fast benefits to give you the pros and cons of juice fasting.
Like with most trends in the health world, juice fasting has its fair share of avid devotees and skeptics. Deciding whether to try a juice fast can certainly be confusing with all the deferring opinions.
That’s why we wrote this article: so that you can make a more informed decision, or at least have more realistic expectations, before embarking on a juice fast for three or more days.
What Are Juice Fasts?
A juice fast refers to when a person limits their dietary consumption to only fruit or vegetable juice for a set period of time. Most juice fast regimens allow unlimited amounts of water to drink and sometimes tea, depending on the type of tea.
Serious juicers will usually invest in juicer machines, which facilitate extracting juice from the rest of the fruit or vegetable. Thus, you may be able to throw in whole fruits and vegetables without peeling or cutting them. The machine does all the work of separating out fibers, pulp, and skin.
If you don’t have a juicer, a blender can work as well, but you’d have to manually segregate any fiber, skin, and pulp if you only want pure juice. You can use a fine mesh strainer for filtering, though this process may become tedious if you want to juice regularly. (Personally, I would rather blend and consume the whole fruit than undergo the hassle of extracting pulp and fiber in this case!)
Many companies or juice stores now sell bottled juices as well, if you want the convenience of pre-made fruit or vegetable juices. However, the cost is expectedly a lot higher than making juice yourself.
The Most Popular Purported Juice Fast Benefits
Why do people engage in juice fasts? Here are the most popular juice fast benefits that proponents list:
Weight loss is a very common driver behind juice fasting, often propelling certain juice fasts to become diet fads or trends. In fact, I know many people who have tried juice fasts in a quest to lose weight fast. We will discuss later whether juice fasting works for this purpose or not.
Detoxing is also popularly listed among juice fast benefits, i.e. purging your body of “toxins” that have accumulated inside either through your diet or environment.
Perhaps related to the notion of detoxing is the common belief that certain juice fasts can cure certain health or medical conditions, including cancer.
Vitamins and Minerals
Since fruits and vegetables are chock full of vitamins and minerals, many people believe juice fasting provides a rainbow of important nutrients. This belief is not so much a main driver for people to engage in juice fasts, but is a common justification for the healthiness of juice fasting, i.e. that people won’t become malnourished while on a juice fast.
So, though technically not a motivating reason for juice fasting, we’ve included it for the sake of discussing the pros and cons of juice fasting and juice fast benefits.
Research on Purported Juice Fast Benefits
Let’s examine some research or medical opinions on the purported juice fast benefits that we listed above.
We found no formal studies documenting sustained weight loss from juice fasts. Short-term weight loss is definitely common, as this study showed participants lost weight during a 3-day juice fast, but studies are lacking on weight loss maintenance.
Although, if you think about pure logistics, most people’s ability to lose weight during a juice fast makes sense. The average American consumes about 3,800 calories a day per the United Nations’ estimate, even though the minimum requirement is 1,800 calories per day (give or take per personal factors).
To equal that average consumption of 3,800 calories a day, a person would have to drink a lot of juice during a juice fast. As an example, where one cup of apple juice contains about 110 calories, a person would have to drink over 34 cups of juice in one day to reach 3,800 calories. Most people would not drink that much juice day after day.
Although research supports that total caloric intake correlates to weight gain, research also supports the difficulty of maintaining weight loss. Also, any quick pounds you shed from juice fasting is likely to be water weight rather than fat loss, particularly if your juice fast only lasts a few days.
The latter likely accounted for my experience with juice fasting. When I joined my friend in her juice fast over a decade ago, I lost around 10 pounds from the fast, but regained the weight afterwards. She also regained any weight that she lost from the fast.
Thus, unless you stick to a lengthy, multi-week or -month juice fast, you’re unlikely to lose weight in the form of actual body fat. You also have to remember the very real possibility of regaining the weight with your body’s quest to resort to its former weight.
No formal, peer-reviewed studies support detoxing as a result of juice fasting, yet it’s one of the most popular benefits proponents list among juice fast benefits.
Skeptics of juice fasts will argue that your body has sufficient mechanisms to detox without the need for fasting.
Research supports sweating is one of your body’s primary ways of eliminating toxins like lead, mercury, and arsenic. Urinating out toxins is the other main way.
Given that water is important in ensuring proper organ functioning, and in transporting toxins through your body, you could argue that juice fasting promotes detoxification by likely increasing a person’s water intake during a fast. However, this argument credits increased water intake more so than juice intake specifically.
Thus, segregating the specific components of juice versus water in the ability to aid detoxing is difficult without further evidence.
No formal, peer-reviewed studies have specifically documented juice fast benefits on various illnesses or medical conditions. However, proponents of juice fasting continue to promote juice fasts’ ability to cure minor or major medical conditions.
Fruits and vegetables undoubtedly offer many beneficial vitamins, minerals, and antioxidants. Thus, we could surmise that ingesting these beneficial substances should improve our overall health. The question becomes whether these health benefits are enough to fight any major medical conditions.
This study concludes that consuming fruits and vegetables can reduce the risk of cardiovascular disease, cancer, and mortality generally. However, other research is inconclusive on whether fruits and vegetables can actually treat or prevent conditions like cancer, diabetes, poor bone health, and heart disease.
This study showed that a three-day juice fast improved the gut microbiota (i.e. more beneficial bacteria and less harmful bacteria) in participants. However, their gut microbiota basically returned to their prior compositions after the fast when participants resumed former eating habits.
Your gut’s bacterial composition is, indeed, very important to overall health. Thus, the popular push for consuming more probiotics like yogurt and kombucha in recent history. However, as the study showed, you do have to continuously foster a healthy gut environment for it to last.
Thus, we can reasonably assume that fruits and vegetables (or their juices) can benefit our health and perhaps even provide a convenient way to “reset” our gut health, but viewing a temporary juice fast as a silver bullet for conferring lasting health or curing major illnesses would be inaccurate.
Vitamins, Minerals, and Antioxidants
Science has long supported that certain fruits and vegetables can be great sources of vitamins, minerals, and antioxidants. Thus, drinking vegetable and/or fruit juice should naturally provide you with these substances. (Though if you’re into antioxidants, you should not only check out our article, 6 Incredible Health Benefits of Green Tea, where green tea is chock full of antioxidants, but also Top 4 Inspiring Apple Cider Vinegar Health Benefits, which explains apple cider vinegar’s enhanced antioxidant properties!)
However, the main question in undergoing a juice fast is whether these vitamins and minerals are enough for your body during a prolonged fast. For instance, you may not consume enough fat during a juice fast for you body to absorb fat-soluble vitamins.
Thus, although you may be consuming more of the substances fruits and vegetables offering during a juice fast, you may be depriving yourself of healthy substances found in other types of food by limiting yourself to only juice during an extended period. The latter practice could actually harm your body.
We will touch on more of this subject in the next section.
Risks of Juice Fasts
Oxalates are compounds found in certain fruits and vegetables that bind to calcium inside our bodies, which can result in kidney stones.
Leafy green vegetables like spinach are particularly high in oxalates. Research confirms raw vegetables contain the most oxalates versus cooked vegetables. (See our article, Make Green Smoothies Healthier + Low-Sugar Guaranteed | Recipe, for a low-oxalate smoothie option.)
Because juice fasts rely on raw fruits and/or vegetables, if you are on a juice fast for an extended period of time, be aware of the risk for kidney stones.
Lack of Dietary Fiber and Other Nutrients
This study shows how blending fruit into juice results in the final juice containing more nutrients than simply extracting the juice through juicing (i.e. extracting juice, but excluding pulp and other components). Thus, excluding parts of the fruit that you may otherwise consume if eating whole fruits can reduce the fruit’s nutritional value.
If you use a juicer machine, the machine also removes most of the fiber content from the fruit by excluding pulp and fiber. Research shows that fiber promotes beneficial bacterial growth in your gut, among other health benefits.
Thus, consuming only the juice from fruits not only diminishes the overall nutrient content of the fruit, but when you couple excluding other types of foods with a juice fast, then you may lack even more nutrients overall while juice fasting.
Lack of Protein
Fruits and vegetables are not typically high in protein. Research supports the importance of consuming protein for good health, including for proper muscle and organ functioning. Also, eating protein helps maintain the muscle mass that you have.
Consuming an inadequate amount of protein can result in muscle loss. Thus, keep in mind that weight loss during a prolonged juice fast may consist of muscle loss.
So long as you don’t engage in very prolonged juice fasts (i.e. weeks or months in duration), then I don’t see the harm in doing a juice fast every now and then. However, you should recognize the reason you want to fast to avoid any potentially unrealistic expectations or outcomes.
For instance, expecting to lose a lot of weight in three days and to maintain the weight loss is unrealistic if most or all of that weight is water weight.
Also, for anyone who doesn’t maintain a relatively clean and healthy diet, a juice fast may help “reset” your gut biome and other health meters temporarily, but resorting to your old dietary and lifestyle habits after the fast will eventually erase any juice fast benefits.
In that respect, a juice fast could be a good “kickstart” into a new dietary regimen if you plan to eat clean thereafter and perhaps crave a more dramatic opening sequence.
However, if you don’t plan to change your eating habits after your juice fast concludes, then you’re unlikely to see any lasting juice fast benefits. So, just take any magical claim of weight loss or detoxing in one to three days with a grain of salt.
Please comment below with any thoughts you have on juice fast benefits or if you have any experience with a juice fast. Inquiring minds want to know!