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. Hi doctor, im a 22 year old men with lupus .

    Do you know if a long water fast can heal lupus ?do you have any experience with it?

    Im interested 🙂

    1. Dr. Tallis Barker, D.Phil., Nat.Dip. Avatar
      Dr. Tallis Barker, D.Phil., Nat.Dip.

      Hi Sandro,
      Thanks for writing. As it happens, a few weeks ago I actually finished working with a client who healed from Lupus over a series of extended water fasts – and this wasn’t the first time either. So the answer to both your questions is yes!
      All the best,
      Tallis

  2. Hi, I’m on a fast right now and I’m wondering if you’ve seen clients get cured from PCOS and PCOS hair loss?

    1. Dr. Tallis Barker, D.Phil., Nat.Dip. Avatar
      Dr. Tallis Barker, D.Phil., Nat.Dip.

      Hi Bex,
      Thanks for writing. Yes PCOS and hair loss can be healed through water fasting, but both of these issues involve complex hormonal imbalances. As such, this can take a lot of time to address, so more than anything else it usually takes patience in accepting the pace of your body’s healing metabolism…
      Hope this helps,
      Tallis

  3. William Shepley Avatar
    William Shepley

    Hi, I’m currently doing a 21 day water fast.
    I have added pink salt(about 1 teaspoon a day). I’m on day 17. I’m 60 , I undertook this to heal any issues I may have. One being high blood pressure. The other gut issues.
    I would get dull pains on my lower left side(sigmoid colon). Last year on my annual blood tests and colon screening I came back ok. Will taking the salt interfere with the healing process? Also will adding 7 days to the fast further my goals?

    1. Dr. Tallis Barker, D.Phil., Nat.Dip. Avatar
      Dr. Tallis Barker, D.Phil., Nat.Dip.

      Hi William,
      Thanks for sharing. Taking salt on a daily basis definitely interferes with the body’s ability to lower blood pressure while fasting. Just think about it: salt makes you retain water, and water retention adds to fluid pressure throughout the body. – And as we all know, salt raises blood pressure in everyday life. Or in this case, while fasting, it will prevent your body from being able to fully lower blood pressure. One teaspoon per day is a lot…
      Hope this helps,
      Tallis

  4. Dear Tallis,

    I have been diagnosed with the large haemorrhagic cyst on my left ovary 22 x 18 x 17. Could water fasting help to reduce the size of the cyst? I’m otherwise healthy and my blood test results are good.
    The doctor has suggested surgery, however I would do anything to avoid it.

    I’m finding your posts empowering and therefore planning on embarking on a long fast.
    Leona

    1. Dr. Tallis Barker, D.Phil., Nat.Dip. Avatar
      Dr. Tallis Barker, D.Phil., Nat.Dip.

      Hi Leona,
      Thanks for writing. There’s no question that ovarian cysts can respond well to extended fasting. If you’ve not already seen it, this article on the homepage describes one such case:
      https://waterfasting.org/healing-ovarian-cysts-with-water-fasting/

      However, it’s also important to know that large cysts like this don’t simply appear out of thin air. So when you say you’re otherwise healthy, it’s more likely to mean that your body has been able to maintain a level of homeostasis (equilibrium) through whatever stressors have ended up causing the growth of the cyst. Blood test results may be good, but they only show what’s in the blood – and not what’s happening in the tissues. When I’m working with a client, we always take a look at their case history in order to try and identify the underlying stressors. Doing so gives insight into how long you might need to think about fasting.

      Hope this helps,
      Tallis

  5. I have undertaken a couple of short to moderate length fasts (up to 10 days) in the past. I would like to target my high blood pressure that has never been sustainably controlled or explained by mainstream medicine. Generally speaking, when during an extended fast does that begin to regulate? Do you have any videos addressing high blood pressure and water fasting available?

    1. Dr. Tallis Barker, D.Phil., Nat.Dip. Avatar
      Dr. Tallis Barker, D.Phil., Nat.Dip.

      Hi Gclayhale,
      Thanks for writing. There’s no question that extended water fasting is the best thing you can do to permanently lower your blood pressure. I’m currently working with a client who got off three different BP meds during her fast, and is now stable at just over 120/80 three weeks after her fast. She will be undertaking a second fast later this month to finish the job.

      I’m afraid I don’t have any videos on this subject because of two reasons. First, because of the various causes of blood pressure, different people need different lengths of fast in order to permanently heal. However long you do need, though, it’s highly likely we’re talking about a fast on the order of 2, 3, or 4 weeks rather than just days. Second, because of the prevalence of individualised meds for people with chronically high BP, I can’t make public comments which apply to everyone. Rather, it is a question of establishing a personalised middle way on a client-by-client basis, in which meds are reduced as quickly as possible during a fast but without spiking BP in the process.

      Hope this helps,
      Talli

  6. Have you ever worked with someone with tinnitus and seen it resolved in their body? I have done an 11-day water fast in the past. Day 4 was tough; days 5-9 were euphoric, and then around day 10, I was exposed to a virus and got sick. I was interested in pursuing a long-term fast. I am fat-adapted, but I have plenty of reserves to work with 😉

    1. Dr. Tallis Barker, D.Phil., Nat.Dip. Avatar
      Dr. Tallis Barker, D.Phil., Nat.Dip.

      Hi Tim,
      Thanks for writing. Yes, I’ve worked with clients who have healed from tinnitus during their fast. However, you’d need to think about working with longer fasts, and in my experience it would need to be at least 21 days. Also, there are different causes of tinnitus. Fasting more easily heals tinnitus in cases caused by hormonal imbalances (most typically adrenal), as opposed to those caused by structural damage to the inner ear.
      Hope this helps,
      Tallis

  7. Have you ever had a client heal from cirrhosis of the liver with water fasting?

    1. Dr. Tallis Barker, D.Phil., Nat.Dip. Avatar
      Dr. Tallis Barker, D.Phil., Nat.Dip.

      Hi Tressa,
      Thanks for writing. The liver is a hugely regenerative organ, and this does include the ability to heal from cirrhosis through an extended water fast. However, when I’m working with a client who has a damaged organ of detox – such as the liver or the kidneys – it’s also extremely important to make sure that the detox of the water fast doesn’t overwhelm that organ. To that extent, I’d definitely recommend working with an expert such as myself, to help ensure that you don’t overstep the limits of your liver imposed by the cirrhosis.
      Hope this helps,
      Tallis

  8. After reading this and all of your responses to comments, I’m very intrigued by a longer fast. Can I heal rheumatoid arthritis and Hashimoto’s with extended fasting? I assume I’ll need to do 40 days. I’m post-menopausal with low sex hormones and 80+ lbs overweight. In the past I’ve done ADF, IF (4-8 hour window) and 3-5 day fasts but it’s been awhile.

    1. Dr. Tallis Barker, D.Phil., Nat.Dip. Avatar
      Dr. Tallis Barker, D.Phil., Nat.Dip.

      Hi Tammy,
      Thanks for writing, and glad that the website has opened your eyes to some of the potential benefits of fasting! I’ve worked with dozens of clients who have healed from RA and hypothyroidism. Without looking at your case history in much greater depth, it’s hard to say whether you’d need 40 days, or whether it would make more sense to approach these issues through a series of fasts. The fact that there is a hormonal element does suggest that you’d need to be thinking about at least (a) 21-day fast(s). Do be aware that if you’re taking meds for your symptoms, it will be extremely important to manage dosage appropriately both during and after the fast!
      All the best,
      Tallis

  9. I’m taking Stelara injections for Crohn’s disease, which at this point is really just a stenotic ileocecal valve. How long would I need to be off the Stelara for a water fast to be effective? Something tells me that being on a drug that changes my physiology would negatively effect a fasting attempt.

    1. Dr. Tallis Barker, D.Phil., Nat.Dip. Avatar
      Dr. Tallis Barker, D.Phil., Nat.Dip.

      Hi Tony,
      Thanks for writing. Helping clients to manage medications before, during and after a fast is an extremely important part of making a healing fast both as effective and safe as possible. I can’t comment on individual cases here in a public space, which could lead to misunderstanding and misapplication by others. What I can tell you is that Stelara has a relatively long half-life, and this would have to be taken into consideration along with a potential return of Crohn’s symptoms if you came off it too soon. It’s a delicate balancing act at the very least.
      Hope this helps,
      Tallis

  10. Hi Tallis Barker,

    Does body fat percentage matter when proceeding with extended fasting?

    I’d love to know your thoughts around a person who is in shape and proceeds with fasting for long periods of time, although having low body fat.

    Thank you

    Miguel Perez

    1. Dr. Tallis Barker, D.Phil., Nat.Dip. Avatar
      Dr. Tallis Barker, D.Phil., Nat.Dip.

      Hi Miguel,
      Thanks for writing. To be honest, I’ve literally never had a client who is healthy and in good shape, who hasn’t been capable of fasting at least several weeks. The only cases in which low weight becomes a concern involve clients suffering from certain chronic health issues.
      So if you’re referring to yourself as the ‘person who is in shape’, go for it!
      Tallis

      1. Hello Tallis,

        Thank you for your response! I was fasting at the time of writing, I was on day 6 when I felt extreme hunger or I was going through a healing crisis. I broke my fast that day, I felt as though most of my fat was lost and I felt my muscle begin to diminish. It was the longest I’ve fasted!

        Thank you

        1. Dr. Tallis Barker, D.Phil., Nat.Dip. Avatar
          Dr. Tallis Barker, D.Phil., Nat.Dip.

          Hi Miguel,
          Congratulations on finishing your longest ever fast!
          Just to add: it’s unlikely that you were actually experiencing any muscle loss, even if you felt extremely weak. Helping clients decide when to end their fast is an important part of my job, but only very rarely do people actually get to the point where they’re truly running out of fat. Fasting on your own, though, it always makes sense to err on the side of safety.
          All the best,
          Tallisd

  11. In my mid to late 20’s, I did a water fast on my own for 21 days. I was overseas in a South Pacific island with the purest water sources. I literally came out healed and full of energy more than I had ever known even as a teenager. I felt healthy and still now in my 40’s, have more energy than I had when I was a teenager. It’s been a long time since I’ve done a long water fast and today I’m going to begin to embark on one. I found your website today. Thank you for it!

    1. Dr. Tallis Barker, D.Phil., Nat.Dip. Avatar
      Dr. Tallis Barker, D.Phil., Nat.Dip.

      Hi Layna,
      Thanks for sharing. You’re very welcome, and I wish you all the best on your water fast 🙂
      Tallis

  12. William Anderson Avatar
    William Anderson

    You mention adding electrolytes can reduce healing during fasting. Does this mean that we should be leaning more towards a dry fast over a water fast that wants you to have .5 oz per pound of weight. I’ve found that drinking excess water tends to deplete mass amounts of electrolytes. Example: around day 6 of current fast, I had extremely painful cramps in my calves, which lead me to drinking some pickle juice. I’m currently in day 11 and have taken electrolytes and potassium to limit this from happening and have tried to back down on water consumption to keep from leaching out the minerals in my system.

    1. Dr. Tallis Barker, D.Phil., Nat.Dip. Avatar
      Dr. Tallis Barker, D.Phil., Nat.Dip.

      Hi William,
      Thanks for writing. In my view, there is a time and place for dry fasts, but this has nothing to do with electrolyte levels. Yes, drinking excess water does deplete mass amounts of electrolytes – so the solution is not to drink excess water :-). When somebody repeatedly suffers from muscle cramps when fasting, there are multiple possible causes beyond true electrolyte depletion (although it’s also true that adding electrolytes will usually resolve the symptom on the surface level). Whatever the superficial cause of cramping, on a deeper level it almost always indicates a metabolic imbalance of some kind, in which case an appropriate longer-term fasting protocol is likely to gradually resolve the issue.
      All the best,
      Tallis

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