Water fasts versus juice fasts: how are they different, and what are the pros and cons of each?


(1) Video lecture

(2) Article

  • What is a water fast?
  • What is a juice fast?
  • The advantages of water fasts
    • The benefits of fully switching off digestion through a zero-calorie approach
  • Raw strength can also be a disadvantage
  • The advantages of juice fasts
    • Greater physical strength during juice fasts
    • Greater length of juice fasts
    • Societal acceptance
    • An introduction to water fasting
  • Combining water and juice fasts
  • See what works for you!

Video lecture (10:00)

Many clients come to me assuming that a water fast will feel similar to a juice fast. The two, however, are very different, and this often comes as a surprise to them! This video and newly expanded article take a look at how water fasts differ from juice fasts, and discusses the pros and cons of each.

What is a water fast?

The essence of a water fast – and what distinguishes it from any juice fast – is that the liquid you drink contains zero calories. Although this primarily means water, certain water fasts also allow herbal teas, especially when the reasons for fasting are physical (as opposed to spiritual).

What is a juice fast?

To a greater or lesser degree, all juice fasts involve the drinking of liquid which contains calories. This can take a variety of forms, such as fruit juices, vegetable juices, clear vegetable soups or a combination of all of the above. A whole range of protocols exist, ranging from approximately 200 calories per day to no caloric restriction at all.

(Note: traditionally, the word ‘fast’ has always referred to a zero-calorie intake. In this sense, a ‘juice fast’ should be called a ‘juice diet’ or ‘juice cleanse’. Following modern usage, though, I shall continue using the term ‘juice fast’ here.)

The advantages of water fasts

In understanding how water fasts are different from juice fasts, it ultimately all comes down to a single factor: strength. A water fast provides a deeper, stronger cleanse/detox and more powerful healing than any juice fast. It’s that simple.

There’s no question that juice fasts can offer a strong potential for healing. Low-calorie protocols like the Buchinger fast have even been applied as alternative cancer therapies. However, as much as the calories in such juice fasts benefit the body with high-quality nutrition – something which in itself should not be underestimated – they can never compete with water fasts in terms of raw cleansing because juice fasts never allow the digestive system to fully switch off.

The benefits of fully switching off digestion through a zero-calorie approach:

(1) Ketosis during a water fast is always stronger than a juice fast because the body doesn’t have to process incoming carbohydrates, which work against the body establishing ketosis in the first place. Stronger ketosis means stronger cleansing because toxins are released from fat cells. Even a ketogenic diet doesn’t help much in this respect, because any intake of calories means that the body doesn’t have to burn its own fat, where toxins are stored.

(2) Because of zero calories ingested, it means you expend zero energy for digestion. It is estimated that up to 30% of our daily energy requirements is consumed simply through digesting food, so bringing this to 0% means that a lot of extra energy is available for cleansing.

(3) Perhaps most importantly, it is only by totally eliminating food intake that the immune system is able to reach full strength and spread fully throughout the body. (For details about how this takes place, please see my article ‘A stronger immune system‘.) As a result, there is a clear quantum leap in efficacy between the lowest-calorie juice fast and any water fast.

Raw strength can also be a disadvantage

For those who don’t already have some fasting experience, as well as those who carry a high toxic load with a suppressed or weakened immune system, water fasting can sometimes prove to be too strong.

In such cases, physical detox symptoms can become totally debilitating with low energy levels, headaches, nausea and body aches. Emotionally, too, a water fast can be too strong – especially when combined with heavy detox symptoms. But even if your body feels fine, the simple lack of any sustenance or taste during a water fast can be hard to bear psychologically, especially for those without much fasting experience. It can feel too relentless, without food providing any degree of comfort at all.

Ultimately, the main danger of a water fast’s strength is in the increased likelihood of breaking off the planned fast’s original length. (For clinical dangers of a water fast, please see my video-article: ‘Is water fasting safe?‘) In this sense, a ‘stronger’ water fast can actually become weaker than a juice fast if you lack the stamina to complete it.

Check out the webshop on waterfasting.org

The webshop offers downloadable fasting plans and guides to help make your water fast a success.

The advantages of juice fasts

Greater physical strength during juice fasts

If the main advantage of a water fast is its cleansing and healing strength, then the main advantage of a juice fast is the higher level of physical strength experienced during the fast. Given that calories are going into your body during such a fast, you’ll simply have more physical energy. Not only does this make it much easier to get through the day physically (and especially so if you have to continue your job during your fast), but on an emotional level too the higher energy levels can help significantly.

If your body is feeling stronger, your motivation to continue the fast is also likely to be stronger. Calories equal comfort. In this respect, the only potential downside of a juice fast’s calories concerns the risk of wanting more and more ‘comfort’, which can lead to things spiralling out of control. For some people the clearer, black-and-white parameters of a water fast – ie. that you’re consuming nothing but water – is easier to maintain than the ‘grey zone’ of a calorie-restricted protocol. Similarly, some people also find that a water fast’s complete destimulation of the digestive system allows hunger to switch off more effectively.

Greater length of juice fasts

Even if it comes at the price of lower levels of cleansing and healing, the increased levels of physical strength also present another advantage. Juice fasts can last much longer than water fasts. Whereas only a tiny minority of people ever contemplate undertaking a 40-day water fast, many more are likely to consider a juice fast. In my experience, for instance, clients with no fasting experience feel comfortable considering a 1-3 day water fast, whereas they are generally happy to try a 7+ day juice fast. In principle, many juice fasts can easily last a month or two, especially those based on fruits, in which the overall caloric intake isn’t much lower than that of a healthy everyday diet.

Societal acceptance

Another advantage of juice fasts is the fact that they are accepted by society, whereas water fasts are still (mistakenly) considered extreme or dangerous. This may not seem important, but when you feel physically or psychologically challenged by a fast, the support of those around you can really lift your spirits. In contrast, having to deal with the concern and resistance of others only drains your limited energy further.

An introduction to water fasting

Juice fasting also provides a very smooth path towards water fasting. The vast majority of my clients, for instance, come to me after having already experimented with juice fasting. I too reached the point of considering my first water fast only after feeling comfortable with juice fasts. It is a completely natural progression. From the full calories of an everyday diet, the restricted calories of a juice fast just seem much more attainable than the zero calories of a water fast.

Juice fasting provides also the perfect introduction to water fasting for those who are initially unable to water fast. For those few people whose toxic load prohibits water fasting, juice fasting can be used to cleanse more gently: until the stronger cleanse of a water fast no longer risks excessive detox symptoms. For those who simply find 24 hours without food too daunting, juice fasting can boost the self-confidence necessary to try a water fast.

Combining water and juice fasts

Many people ask whether it’s okay to do a water fast before or after a juice fast. The answer is a most definite ‘yes!’ In this respect, there are several ways to combine the two types of fast.

One popular method is to insert a short water fast into a longer juice fast. For instance, a 24-36 hour water fast can easily fit into the middle of a week-long juice fast. In order to maximise the benefits, you might consider beginning the juice fast at a comfortable caloric intake, and then reducing it day by day until reaching the water fast. Over the last few days of the juice fast, you can build back the calories again, so that the transition back to your everyday diet is relatively seamless.

Juice fasts work well immediately before any water fast. As discussed above, juice fasts permit an initial degree of cleansing before the water fast takes it to the next level. Although this usually smoothes out detox symptoms, sometimes the opposite happens, with the immune system eager to jump into overdrive once calories are reduced to zero.

Juice fasts work particularly well after extended water fasts, especially when someone has a serious health issue. Any refeeding program should focus on vegetables and fruit, and a juice fast provides the gentlest way of delivering the nutrients of these food groups without the risk of overwhelming digestion.

If you return too quickly to a normal diet, you risk encountering both digestive problems as well as ‘refeeding syndrome‘. This is a potentially fatal complication caused by the change from ketosis back to your everyday metabolism. After an extended fast, the body cannot be rushed in this process.

If you have any doubts, I offer a downloadable 67-page PDF which covers refeeding for any length of fast.

See what works for you!

I hope this article has given food for thought about water fasts, juice fasts and some possibilities for combining the two. By and large, there are no rights or wrongs here. Mostly, there are only rights! Really, the most important thing is to experiment and see what works for you. Enough theory: so stop reading and try it out for yourself. Your body will love you for it!

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2 responses to “Water fasts versus juice fasts: how are they different, and what are the pros and cons of each?”

  1. Great article. I’m 63 yrs of age and have been fasting off and on since 1979. That said, the advice given is excellent, to the point where I have incorporated the “juice water juice ” regimen ; simply varying the length of days. I find that at my age, my fasts do not exceed 15 days in duration. Its what works for me ! Thanks again, Jack K , Michigan. USA

    1. Tallis Barker, D.Phil. Avatar
      Tallis Barker, D.Phil.

      Hi Jack,
      Glad you found the article useful, and all the more so coming from someone who has as much experience as you do!
      All the best,

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