Water Fast Coaching and Articles

Dr. Tallis Barker, D.Phil., Nat.Dip., NA.Dip., Naturopathic Water Fasting Consultant & Coach

14–40 Day Water Fasts: Healing Power, Benefits & Risks

Why would anyone fast for two weeks—or more?
For those seeking the deepest levels of physical, emotional, or spiritual healing, a 14–40 day water fast may offer what shorter fasts cannot. Once your body has fully adapted to ketosis, longer fasts allow for profound detoxification, immune recalibration, trauma release, and sometimes even the reversal of chronic illness. However, they also require care, preparation, and guidance.

In this article, you’ll learn what happens in extended fasts, how to prepare and refeed, and how to distinguish between a true healing crisis and signs that it’s time to stop.

Note: Extended water fasts of 14–40 days are powerful but demanding. They should never be undertaken without expert supervision, especially if you have chronic health issues, take medications, or are unsure of your body’s limits. Always consult your doctor before beginning any prolonged fast. This article is for educational purposes only and does not replace medical advice or personalised coaching.

To address chronic illness, deep trauma, or long-standing toxic load—levels that shorter fasts usually can’t reach.

Yes—if done without guidance. Extended fasts can deplete fat, protein, or electrolytes if pushed too far.

A temporary flare-up of past symptoms as the body clears deeply stored illness. It can be intense but is often part of the healing.

If true hunger returns, or signs point to electrolyte imbalance, it’s time to break the fast safely.

Very slowly and intentionally, with light plant foods. The longer the fast, the longer the refeeding process should take.

CONTENTS:

  • Introduction
    Why extended fasts are rare—but sometimes necessary—and what makes them so powerful.
  • Benefits of Extended Water Fasts (14–40 Days)
    How deeper fasting supports chronic illness reversal, detox, and complete healing.
  • Physical, Emotional, Spiritual Healing
    What happens beyond the body: trauma release, ego dissolution, and ancient fasting traditions.
  • Experiencing a Healing Crisis
    When old symptoms reappear—and how to know whether to continue or stop.
  • The Dangers of Fasting Too Long
    Understanding the risks: fat/protein depletion, electrolyte imbalance, and misreading hunger signals.
  • Refeeding After an Extended Fast
    How to break a long fast with safety and care—and why this step is just as important as the fast itself.

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Why in the world would you ever want to fast for two weeks or more?

If only a tiny percentage of people in the Western world ever undertake a water fast of any kind, then only a tiny percentage of people who water-fast will ever undertake an extended healing fast of 14 days or more. Why? There’s simply no need. For everyday cleansing and healing, occasional 7-10 day fasts combined with regular short fasts such as the 3-day or 36-hour water fast should keep you in excellent health.

Benefits of extended water fasts (14-40 days):

However, in order to reach the deepest possible level of healing and reap the greatest benefits, it is necessary to dig deeper with a longer fast. For instance, certain serious physical illnesses – those often deemed incurable by Western medicine – require the cleansing of an extended fast in order to permanently heal.

Despite what most modern medical doctors may tell you, conditions as wide and varied as Long Covid, gut issues (such as IBS, ulcerative colitis and food intolerances) adrenal issues (CFS/ME), diabetes, chronic high blood pressure, autoimmune disorders (including allergies and asthma), as well as certain types of tumors are all potentially curable. I know this for a fact, because I have personally worked with clients suffering from ALL the health issues listed above to the point of a full healing.

Dr Barker regularly speaks at international conferences on water fasting. Below you’ll find his lecture for The Real Truth About Health conference, as well as a panel conversation with Dr. Alan Goldhamer – one of the most recognised names in the field.

As a water fasting coach, I’m privileged to witness this miraculous healing potential of the human body every day! It does take time, though, and in order to heal effectively from chronic illness, the length of the fast must typically last 14-40 days.

In helping clients decide how long to fast, three main factors come into play.

First is the overall symptom picture – that is, the sum total of active health issues, all of which constitute a toxic load contributing to illness. Although, for example, someone may wish to fast in order to heal Long Covid, further questioning almost invariably reveals other health issues in the background, both past and present. Whether presenting with symptoms of their own or whether entirely sub-clinical and ‘invisible’, these apparently secondary issues tell a story of how, over the years, a client has arrived at the present moment.

The second factor which suggests how long a client may need to fast is the strength of their immune system. The primary factors here are age, diet, stress and, in the case of chronic illness, how much the immune system has already been worn down in fighting a war of attrition.

The third factor concerns the degree of prior cleansing – and especially water fasting. Quite simply, the more you’ve already fasted, the more quickly and powerfully your body can mobilise your immune system for healing.

Physical, emotional, spiritual healing:

Beyond physical healing, the deepest emotional and spiritual cleansing can similarly take place only through the sheer length of an extended fast. In fact, what I’ve seen over many years of coaching is that in order to achieve the greatest physical healing, it’s also necessary to surrender emotionally and spiritually to the whole process. A big part of my job is to help facilitate that process.

Although nowadays we tend to remember only the Biblical 40-day fasts of Moses and Jesus, the fact is that many spiritual traditions over the millennia have demanded 40-day water fasts. Even Pythagorus required potential students to undertake a 40-day fast before he was willing to accept them. As much as we balk at the idea of giving up food for such a long time, it’s mostly just a question of unwillingness to forgo the addictions and pleasures of life. Don’t believe the voice of your fears and reluctant ego. You won’t starve to death.

Unless you’re seriously malnourished and underweight to begin with, you carry the better part of 100,000 calories on you, locked in your fat tissue and waiting to be released through ketosis. That’s enough to last you well over 40 days. If you’re overweight, you could potentially fast for much longer (although in most cases this is not advisable).

In other words, getting through a 14, 21 or 40-day fast is often a mind game more than anything.

Letting go of your fears about fasting is just the beginning. The process of surrender also eventually leads to the release of pent-up, self-destructive emotions and, for some people, a catharsis of trauma from the distant past. In doing so, you’ll free yourself: discovering a place of inner calm and spaciousness where you can finally breathe. This is a hugely important part of the healing process.

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

Experiencing a healing crisis:

Although in one respect an extended fast simply continues the notion of a 7-10 day water fast, it is also much more powerful because it gives you the opportunity to experience deeper ‘healing crises‘. As described in the article on the 7-10 day water fast, a healing crisis often occurs towards the end of the first week of water fasting, as the symptoms of old illnesses, injuries and traumas resurface, before being permanently expelled from your body.

A similar process often occurs around the end of the second week of fasting – and this is the reason that if you decide to extend a 7-10 day water fast, it’s worth aiming for at least 14 days. This second healing crisis tends to call forth deeper issues than the first healing crisis, or, alternatively, finishes resolving those issues which were not fully cleared during the first healing crisis. In other words, it’s from the beginning of the second week of water fasting that your body can begin to heal from more serious health issues. Simply, up until this point, your body has been focussed on cleansing the toxins of everyday life (and especially so if you haven’t been fasting regularly).

For the deepest and most serious health issues, healing crises often occur much later into the fast, whether 20, 30 or even 40 days. There’s no way to accurately predict when they will occur. You can only trust your body and let nature take its course…

Occasionally, healing crises can be extremely intense, especially when they occur late into a fast. When this happens, it’s critically important to be able to tell the difference between a healing crisis and a sign from your body urging you to stop the fast. This is where working with an experienced water fasting coach can really help. If it’s a healing crisis, you should ideally try and push through. If it’s not, you should stop immediately! (continues below)

Not every healing process is accompanied by a dramatic healing crisis. Sometimes symptoms of illness and trauma simply begin to disappear. In cases like this – when no clear sign indicates that you’ve obviously freed yourself from a health issue – it can be difficult to know when to end the fast. This is another reason why it’s advisable to consider undertaking an extended fast with the help of an expert who understands the subtleties and symptomatology of fasting. The other main reason for working with a professional is to make sure you don’t overstep your body’s nutritional capabilities, as a prolonged fast begins to reach its physical limits.

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The dangers of fasting too long:

  • Depletion of fat (adipose tissue)
  • Depletion of protein (amino acids from muscle tissue)
  • Depletion of electrolytes

If you continue fasting indefinitely there comes a point where the fast turns into starvation. You obviously don’t want to overstep this mark! For when your fat stores are finally depleted, the body has no choice other than to devour muscle tissue, as well as feed from your inner organs. You’ll do yourself serious damage. Fortunately, though, the body sends a clear sign: extreme hunger. Although it’s unlikely you’ll miss this red flag, it’s also true that normal periods of hunger can develop during an extended fast. The urban myth out there on the internet – that hunger simply disappears on the third day – is a gross oversimplification of what actually happens. On longer fasts, it isn’t uncommon for my clients to believe that ‘true hunger has returned’, and that they should break their fasts. Usually (but not always), this phenomenon simply constitutes a totally normal physiological phase of the fast, or – even more likely – their digestive juices are being driven by an increasing emotional desire to eat. Without someone offering an objective mirror on the outside, it can be extremely difficult to distinguish between the different possible scenarios!

In addition, two other less obvious scenarios demand the end of a fast. The first possibility is that you run out of amino acids (derived from muscle tissue) before you deplete your fat stores. In order to power your body as a whole, it’s true that ketosis is extremely efficient. The problem is that the brain demands another fuel entirely: glucose. And this cannot easily be metabolised from fat tissue. Instead, the body must extract it by breaking down proteins in a process called gluconeogenesis (described in greater detail in my article on the 3-day fast). However, the actual danger of depleting amino acids before fat tissue is largely theoretical. I have never witnessed this happen myself, and it is only likely to arise on fasts longer than 40 days in the case of someone who is morbidly obese with severely atrophied muscle tissue.

The final possibility is certainly a real danger: the depletion of electrolytes (blood salts), especially potassium or sodium. Although unlikely, this process is potentially life-threatening! Understandably, many people decide to take electrolytes while fasting, precisely in order to avoid this scenario. If the sole reason for fasting is to lose weight, then by all means do so! However, if you are fasting because of a chronic health issue, it is critically important to understand that taking electrolytes during a water fast compromises both the deepest cleansing and healing – as I have observed clinically among clients who choose to fast using electrolyte supplementation. (I will delve into the physiology of this in a future article.) Although the danger of electrolyte imbalance usually increases from only about the 21-day mark, it is extremely important to respond to the first warning signs if and when they do arise. Unfortunately, this is difficult to the untrained eye, because the symptoms of potassium and sodium depletion overlap with other totally normal detox symptoms. The key is in understanding the context as well as the overall, underlying symptom picture.

Refeeding:

After you break an extended fast, it’s extremely important to follow a well structured meal plan. In an ideal world, this should be tailor-made to the individual person, based on prior nutritional reserves, any dietary sensitivities, as well as the given health issue for which someone has fasted. When this is not possible, a comprehensive pdf on refeeding can be found in the webshop here:

How to break a water fast?

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. If you have any doubts, I offer a downloadable 86-page PDF which covers refeeding for any length of fast.

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355 responses to “14–40 Day Water Fasts: Healing Power, Benefits & Risks”

  1. I have a series of small nodules along both sides of my neck and in a few in the shoulders. They have been there for a few years and seem to be slowly getting bigger. I have had blood work and it comes back normal. I’m afraid it could be some type of slow growing tumor. I have been fasting for a week on just water. Can I get the same results of a 40 day fast if I would break it up into 2 sessions of 20 days or thee sessions of 14. If so how long should I wait between the fasts. Thanks Shannon

  2. Dear Dr. Barker – thank you for so generously sharing your expertise. I did a 10 day water fast a couple of months ago and felt fantastic, and am preparing to do an extended fast, possibly 40 days, as I find my life is stagnant, crisis after crisis, and I am about 25kg overweight, and I think it would be good for me on a mental, emotional, physical and spiritual level. I am taking medication (100mg or iu – not sure what the measurement is) per day for hypothyroidism. I want to know if I can stop taking it during the fast and if my measurements are on point after the fast, if I can come of it altogether? I really want to come off the meds as I believe they’re affecting my heart. Thank you in advance for your reply. Kind regards.

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

      Hi Lsilo,
      Thanks for writing. Glad you felt so good on your last fast, and I hope your upcoming extended fast continues your healing journey. I can’t comment on individual cases – and especially so when it comes to drugs – but I will say that I do work with numerous clients who do successfully and permanently come off hypothyroid meds during their fast. It’s a balancing act, and every case is different!
      All the best,
      Tallis

  3. I have fasted before, 3,5,10 and 13 days. When I did water only, after a few days, I get intense cramps in my calves. They are so bad that I sometimes scream and have to rub if for a very long time to ease it. They usually happen in the middle of the night and wake me causing me to sit straight up and scream and cry. When I use a small amount of Pink Hymalayan salt once of twice a day, it seems to ease this. Does that interfere with the detox?

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

      Hi Teri,
      Thanks for sharing. Cramps can have several causes: both dehydration as well as electrolyte issues involving magnesium and/or sodium. Taking pink Himalayan salt would certainly help the situation, given that it forces your body to hold on to additional water, but it does also lower the degree of cleansing and healing. So it’s important to understand the cause of the cramps before taking salt! If the issue was low sodium, then it’s the right solution. If the issue was caused by something else, then it acts only as a ‘band-aid’ which also comes at the price of compromising the deepest detox and healing.
      Hope this helps,
      Tallis

  4. Dear Dr. Barker,

    I am 42 yrs old and I just finished my 21 days of water wasting. I had almost no symptoms during fasting except fatigue and my post fasting blood test results are normal.

    However, I missed my period 6-7 days (not pregnant) and no premenopausal symptoms before. Is this normal during prolong fasting? I am worry that this prolong fasting put me in menopause. Is that possible?

    Thank you
    Eda

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

      Hi Eda,
      Thanks for sharing, and congratulations on finishing your 21-day fast. It’s very common for women to miss a period after an extended fast. However, this isn’t because there’s a problem. Precisely the opposite: when the body experiences the depth of cleansing on a 21-day fast, it often decides there’s no need to produce the cleansing force of a period in the immediate aftermath. For the vast majority of women, fasting actually improves any symptoms of (peri)menopause, such as reducing or eliminating hot flashes, and, in my experience, it is probably the best means for maintaining continued good hormonal health into older age. So there’s very little risk here of your fast actually accelerating your trajectory into menopause!
      All the best,
      Tallis

      1. Thank you so much Dr. Barker,
        it makes sense. I actually got my period period back yesterday.

        Gratefully
        Eda,

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

          Glad to hear that Eda, and thanks for the update 🙂
          Tallis

  5. Hello Tallis, I am on day four of a water fast. I was wondering what your thoughts were on herbal teas, specifically hibiscus? I’ve read that it won’t affect autophagy, but wondering what your thoughts are on the subject? Thank you!

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

      Hi Naomi,
      Thanks for writing. There’s definitely a place for herbal teas, including hibiscus – and no, they don’t affect autophagy. More importantly, though, is understanding WHY you’re using them. Is it for their medicinal value? Is it because you’re bored by drinking only water? I’d always argue that the more conscious you are about the motivations and feelings guiding you while you fast, the deeper your experience will be!
      Hope this helps,
      Tallis

  6. Hi Tallis, I’ve read about liver cleansing/flushing (see: Andreas Moritz “The Amazing Liver and Gallbladder Flush”) for years (have never been able to successfully get anything out) and the stones that people say are flushed out of their livers after doing these flushes. Does anything similar happen during a water fast? Is the liver healed from something like fatty liver disease after a water fast?

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

      Hi Chris,
      Thanks for sharing. My experience is that the ‘Amazing liver and gallbladder flush’ produces results for some people and not for others. I’d say that the best thing you can do for your liver is to do a water fast instead :-). Yes, I’ve frequently seen fatty liver disease healed. A couple of years ago, for instance, I had a client who had over 50% fatty liver and fully healed from it on a 21-day fast.
      All the best,
      Tallis

  7. Thank you very much for the article. Really useful read.

    Are there any conditions which from your experience and expertise almost always need longer than 21 days to heal? I’m trying to decide when to break my fast. Unfortunately, I don’t have a medically-tested understanding of my health problems, but I’m morbidly obese, have digestive issues and high blood pressure.

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

      Hi Dee,
      Thanks for writing. Determining the length of a fast is an important decision, and it’s often something which forms an a central part of a consultation when working with a new client. In my experience there are many health issues which usually require more than 21 days. Beyond certain specific issues – such as cancer and neurological issues – which almost always require 40 day fasts, it’s also a question of the number of issues burdening somebody’s health (including the determination of subclinical issues which don’t necessarily show up on tests), the strength of the person’s immune system, and the length of time the person has been burdened with ill health.
      Hope this helps,
      Tallis

  8. Hi Dr Barker, I’ve just discovered your website and am very intrigued, it’s difficult to get comprehensive information about extended fasts like this anywhere else online. I am wondering how long you would recommend fasting for covid vaccine injury (similar symptoms to long covid) and how much weight I should expect to lose in that time? (I need to put some weight on to facilitate the fasting!)
    Many thanks in advance 🙂

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

      Hi Cal,
      Thanks for writing. I’ve worked with numerous clients suffering from vaccine injury. What I can tell you is that fasting is probably the most powerful thing you can do to heal, but the exact protocol has to be tailor-made to the individual case: both in order to maximise efficacy as well as ensure the safety of the client. Many people suffering from Long Covid and vaccine injury are in a truly delicate state, and one of the hallmarks of fasting with any Covid-related issue is the likelihood of complications. It’s extremely important not to push the body beyond what it can manage, and especially so if you’ve already lost a lot of weight. If you need support, you can reach me via the coaching page of the website here: https://waterfasting.org/online-coaching-and-consultations-for-water-fasting/
      All the best,
      Tallis

  9. I’m so thankful for your article thank you. I had bronchitis and pneumonia last month and another bout of bronchitis this month. I decided to do a water fast and I’m on day four to see if I could help clear up whatever my body is dealing with. Would you recommend a seven, 14 or longer fast for deep healing? I’ve never been a smoker, but seem to have been pound to bronchitis and pneumonia for years.

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

      Hi Debby,
      Thanks for writing, and I’m glad you found this article helpful. There’s no question that water fasting is just about the most powerful thing you can do to heal from severe respiratory issues. It’s hard for me to recommend an exact length, as this depends on the individual case, but it’s true that you should probably be thinking of 21+ days if you want to get to the root of the problem. Located deep inside the body, the lungs require a deeply evolved fast to experience major healing – and this takes time.
      Hope this helps,
      Tallis

  10. Hi Tallis,

    I’ve been reading through your site for the past couple days and am inspired by your work. I actually stumbled upon your site after finding your article about a patient of yours who had a 17 cm cyst on her ovary (and also a fibroid). I was just told by a doctor that I had an 11 cm chocolate cyst on my right ovary and I want to try fasting to see if I can dissolve it. I initially thought of going with a 21-day fast like your patient, but I know my husband would freak out as he doesn’t want me fasting at all. So, I’ve concluded that a 14-day fast may be best. Just wondering your experience with women with cysts and if you think 14 days is enough? I don’t have any other cysts or health issues other than high blood pressure. My weight is normal for my size: 120lbs 5’3. I’m actually on day 4 currently. Any advice would be greatly appreciated! 🙂

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

      Hi Valerie,
      Thanks for writing. Glad to hear you’ve been inspired to fast to try and heal your own cyst. Regarding the number of days, 14 is going to go deep into detox, but whether or not it will have time to reach the cyst is something I wouldn’t want to speculate on. If this is your first-ever 14 days fast, the odds are that it probably won’t – but that doesn’t mean the fast is in vain. In order to reach the point where the cyst becomes your body’s prime target, you’re going to have to lower your overall toxic load first, and this is precisely where preliminary fasts can come in handy. When the longest fasts (which are usually the most efficient in dealing with serious issues) are out of the question because of family or work life, I often spend a lot of time working with clients in order to devise the most efficient fasting plan using a series of shorter fasts.
      All the best,
      Tallis

      1. Okay thank you Tallis!

  11. Frank John Kupferer Avatar
    Frank John Kupferer

    I just want to say thank you for this post, it really helped me a lot 🙂

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

      Hi Frank,
      Thanks for sharing, and very glad you found the article useful!
      All the best,
      Tallis

  12. Thank you for answering my questions in the past, Dr. Barker. I have many small issues that have accumulated over time and have been considering a coached extended fast to address all of these. Gallstones seem to be one of the issues. Do you think extended fasting would allow the body to break down gallstones and/or kidney stones? I deeply appreciate all you do.

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

      Hi Subdahl,
      You’re welcome! To answer your question, gallstones are produced in the liver and are delivered to the gallbladder and GI tract via the bile. Fasting detoxes the liver, which lowers the tendency to produce gallstones in the first place. Gallstones also have a tendency to be flushed out during a fast. In terms of kidney stones, a lot is going to depend on the specific type of kidney stone. Those which form from excess uric acid have a theoretical possibility of becoming exacerbated through the raised uric metabolites released through detox. However, in practice I have seen this happen only once in the last few years. Otherwise, it is more likely that a fast will help you to pass any kidney stones (assuming they are not already too large).
      All the best,
      Tallis

      1. Hi Tallis: Thank you very much for your service! I am on day 9 of a fast and have begun experiencing pain from passing gallstones (I know this pain from previous experience). Do you have any suggestions? Thank you again and take care
        Robert

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

          Hi Robert,
          You’re welcome – I’m glad you appreciate the website. I’m afraid it’s difficult to answer your question without having coached together. This is the kind of issue which all depends on context. If you’ve suffered from painful gallstones in the past, we would have looked at this during the pre-fasting consultation. I would have asked about your diet, taken a deeper look at your case history and, based on this, suggested a couple of protocols to reduce the chance of gallstone issues developing during the fast itself. Unfortunately, it’s much harder to mitigate the issue once the fast is already in full swing!
          Hope you’re feeling better by now,
          Tallis

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