Fasting against coronavirus (Covid-19): how to boost immunity and maximize health

For water fasting to heal Long Covid, please click on the link below for my more recent article:
Healing from Long Covid with water fasting

Written at the start of the pandemic, the extended article below argues that the best thing you can do to strengthen your immune system against Covid-19 is to undertake a 7-10 day water fast or, ideally, a 21-day fast as soon as possible (see Section 3). For most people, fasting is also advisable during illness, especially if you begin as close to the onset of symptoms as possible (see Section 4).

Article sections:
(1) A no-win scenario?
(2) Why fasting is your best bet against coronavirus
(3) How to fast in order to prevent illness
(4) How to fast in order to treat illness

CLICK HERE if you need COACHING for your own water fast

(1) A no-win scenario?

The rapid spread of Covid-19 throughout China and, increasingly, across the globe rightly has many people worried. Currently, the number of infections continues to double every few days, with the official death rate holding steady at just over two percent. If this trend continues – and it is only an if – then the number of casualties will eventually extrapolate to many millions of deaths worldwide.

The good news is that there are probably many mild, unreported cases of the virus. This means that the actual death rate is more likely to be lower: closer to that of more common flu viruses (less than one percent).1 This is supported by the fact that a majority of the most severe cases concerns people with already compromised health in middle and old age. In other words, many people who are already healthy and who possess a healthy immune system remain just that: healthy.

The bad news is that, in all likelihood, the genie is already out of the bottle. Governments may be doing their best to reassure us through all the preventative measures publicised in the press. But given an incubation period of up to 14 days and given that transmission can occur before the onset of symptoms, we are fooling ourselves if we really believe we can catch up and contain this infection – and there’s no reason to doubt the estimate (from a recently leaked UK government document) that Covid-19 will infect 80% of the population.

More bad news. Having jumped the species barrier from animals to humans only a few months ago, this year’s coronavirus is an entirely new strain of pathogen. As such, the magic bullet of a safe and effective vaccine is nowhere on the horizon. Likewise, we lack drugs which specifically target the virus. Antibiotics cannot help either, as this kind of medication fights bacteria not viruses, and are prescribed only when a secondary bacterial infection has taken hold. With no current pharmaceutical means to prevent or treat coronavirus, it is left to each of us to take responsibility for our own health.

Many people have begun to wear surgical masks in the hope of escaping infection – not just in China, but also in airports and urban areas across the world. Unfortunately, though, the evidence suggests that masks help only to prevent the spread of infection by those already carrying the virus. That is, most face masks do little to lower the risk of actually catching coronavirus.2

So what can we actually do – beyond quarantining ourselves on a desert island? It’s starting to feel a little like a no-win scenario.

(2) Why fasting is your best bet against coronavirus:

There are viable options. Improve your diet. Exercise. Make healthy lifestyle changes. Unfortunately, though, these modalities work best as a long-term strategy. Such an approach takes literally months or years to boost your immune system to the extent of having a better chance of fighting off illness.

And in this case we don’t have the luxury of time.

Shorter-term strategies focus mostly on taking health supplements, such as Vitamin C, Echinacea and other herbal remedies. These support your immune system in functioning more efficiently, but don’t actually improve the structure of countless individual elements which comprise the immune system itself. As such, supplements will always be of limited help.

The best means to boost your immune system is to practise fasting. Structural improvements to the immune system occur almost immediately: both during and after fasting.

In this article, I will use the traditional meaning of the word ‘fast’, which refers to the zero-calorie intake of water fasting and dry fasting. Juice ‘fasting’ and other reduced-calorie cleanses all promote the immune system, but a zero-calorie fast will always be significantly more powerful in its restorative effects. Fasting has been used throughout history – from ancient to modern times – in order to prevent and heal disease. More than two thousand years ago, Hippocrates (to whom doctors swear their Hippocratic oath) applied fasts to treat all fevers and acute diseases. In the Middle Ages, fasting was used to fight the Bubonic Plague. More recently, Dr. Herbert Shelton, the father of modern fasting, cured typhoid, pneumonia, dysentery and other infectious diseases through fasting.3 I myself regularly fast to prevent the flu – and, on the rare occasion this fails, to treat and mitigate the symptoms of flu. There is no question that water fasting is one of the most effective methods of fighting both bacterial and viral infection.

This is just the beginning. Fasting proves equally effective against non-infectious chronic conditions as well. I have coached hundreds of fasting clients to improve the symptoms of or fully heal from conditions as diverse as asthma, cancer, chronic fatigue syndrome (CFS), colitis, eczema, fibroids, fibromyalgia, food allergies, hypo-thyroidism, IBS, multiple sclerosis (MS), musculoskeletal trauma and tumours. Fasting is also finally beginning to be used in conjunction with Western medicine: for example, in order to help the efficacy of chemotherapy.4

How can fasting work so effectively across such a range of different conditions, both acute and chronic? It’s simple. Fasting provides a massive boost to the entire immune system as well as to overall health: more so than any amount of Vitamin C, Echincea or any lifestyle change (although this doesn’t contradict their use as complementary aids). This is all the more important when it comes to fighting a new strain of pathogen like Coronavirus, to which we have no prior specific immunity.

(3) How to fast in order to prevent illness:

Anyone can fast in order to prevent illness. You don’t need years of fasting in order to do so – although increased practice in fasting brings more powerful results. Similarly, you don’t need to undertake hugely long fasts – although it’s also true that longer fasts affect greater change to your immune system. Ultimately, any fast of any length will help.

Ideally, there are three key points to consider when fasting to prevent illness:

(1) Undertake the longest fast you can comfortably and conveniently manage.

(2) Fast when in maximum health. This way your body can devote the greatest energy to boosting your immune system rather than fighting off a pre-existent condition or illness.

(3) Fast in the period immediately before you expect to be exposed to an infectious pathogen. In the case of Covid-19 that means now, or as soon as possible, especially for those living in Europe or the US. Fasting does boost your immune system over the long term, but the effects are strongest at the end of your fast and in the period immediately afterwards. The longer you fast, the longer this honeymoon period will last.

I’ll continue by describing how I usually fast myself, and then examine other alternatives. In everyday life, what usually works best for me is to do a 7-10 day fast either before or after Christmas, depending on family plans over the holidays. (Unlike in the current situation, most of the time there’s no way to know exactly when you’ll be exposed to winter flu.) Ideally, you want to be exposed in the period following your fast when (1) your body has finished rebuilding itself and (2) your immune system is still working at peak capacity. After a 7-10 day fast, this means about a week or two after breaking the fast. This may be the sweet spot, but the fact is that any such fast will provide added protection for many weeks or even months. So, in normal circumstances, a water fast in the early winter boosts your immune system for any infection encountered through the rest of the winter.

Besides an early winter fast, I also often do another 7-10 day fast in late spring or summer. This provides an additional body memory of getting into deep ketosis (our fat-burning metabolism), which enables quicker and easier access to detox. A spring fast also means that there’s less maintenance cleansing to do during my winter fast, which, in turn, means that my body can focus in boosting the immune system.

This is what works for me. If you’ve never fasted before, even a single 7-10 day fast probably sounds tortuously long. If you do have the determination to follow it through, though, it will significantly boost your immune system. Where there’s a will, there’s a way. The only difference compared to someone with more fasting experience is that the experienced faster is more likely to approach such a 7-10 day winter fast from a stronger baseline level of health, with a lower toxic load.

If you’ve never fasted before and want to maximise your immunity, my advice would be to try a 36-hour fast first: a few days or a week before trying a longer fast. Once you’ve experienced the fact that you can survive a day and a night without food, it will be much easier psychologically to undertake a 7-10 day fast, which is simply 7-10 repetitions of a time period you’ve already experienced. For more information about 7-10 day fasts, please click here.

If you can’t manage a 7-10 fast at all, then even a 3-5 day fast offers a degree of increased protection. The only difference is that it won’t be as strong or last as long. For more information about 3-day fasts, please click here.

For 99.9% of the population, the only reason you can’t manage ANY length of fast is psychological, not physical. If fasting somehow feels impossible, then a fasting coach like myself can help.  

The ideal scenario to boost your immune system against infection is to do a 21-day fast in the period before you expect to be exposed. Your body needs about 21 days to reach maximum ketosis and achieve the maximum potential for cleansing and healing. In addition, having done 21 days of fasting means that you’ll have cleansed the vast majority of toxins from your body (even if this is your first fast), leaving your immune system free to focus entirely on any pathogens in the months to come. – And there’s no doubt that a 21-day fast will boost your immune system for many months afterwards. For more information about extended fasts, please click here.

I frequently get questions from people concerned that a 21-day water fast will somehow weaken their immune system. Nothing could be further from the truth. Yes, during the fast you’ll probably feel weaker. But this is precisely because your body has moved its emphasis from the surface of your body, including muscles, to strengthening its innermost workings, such as the immune system.

(4) How to fast in order to treat illness:

Sometimes prevention isn’t enough. Sometimes it’s necessary to fast in order to fight off a bug which has already begun to take hold. For normally healthy people, it’s always best to fast as soon as possible in such cases. However, for those with already seriously compromised immune systems, it is NOT always advisable to fast. In these cases, you should ALWAYS talk to a medical doctor first.

Fasting to treat illness certainly works. As mentioned above, humankind has done so at least since the ancient Greeks, if not earlier. But it also goes deeper than this. It’s in our biology. When any animal becomes ill, the first symptom often appears as a lack of appetite. Instinctively, animals know that fasting helps to heal them. The only reason most humans don’t do the same is because of food addictions and fear of hunger.

I remember the first few occasions I tried fasting to beat a cold or the flu. I was relatively new to fasting at the time. Sometimes the bug would just clear up – almost magically – within a day or two. But other times it wasn’t a fun experience. My symptoms would get worse, sometimes quite a bit worse, before they showed any sign of getting better. In fact, I wondered whether fasting was helping at all.

Over the years things changed. Nowadays, on the rare occasions that preventative fasting fails, fasting to treat illness almost always brings a swift and painless end to whatever bug is in my system. Starting a fast upon the onset of symptoms usually results in regaining health after two or three days, even in the case of the flu. During this time I also feel much better than those around me who aren’t fasting and are instead suffering a full spectrum of symptoms.

My own experience of fasting to treat illness is representative of most people. If you are new to fasting, then a lifetime’s accumulation of toxins is probably locked into your body – unless you breathe clean air, eat 100% organic, drink water fresh from a mountain spring and enjoy a totally stress-free life. Fasting while carrying such a toxic load means that you’re fighting a war on two fronts: against the pathogen and against yourself. If, on the other hand, you regularly fast, then you only have to face the pathogen. And let’s not forget that you’re also facing the pathogen with an immune system in prime condition, thanks to prior fasting. Fasts to treat illness never feel as easy and light compared to those when you’re completely healthy, but it’s a small price to pay in order to avoid coming down with full-blown symptoms.

For those who have never fasted before, I would stress that fighting a war on two fronts while fasting is usually still a better proposition than fighting against a pathogen alone while eating, due to the vastly increased power of the immune system while fasting.5

To return to coronavirus and Covid-19, the truth is that no-one can predict with any degree of certainty how the current epidemic will transpire. The only certainty we do possess is in our own individual actions. The only certainty we do possess is in the knowledge that fasting boosts the immune system more powerfully than any other tool at our disposal. Let us apply our own individual action to that knowledge. Let us fast.

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1. Harvard Gazette:

2. BBC:

3. Herbert Shelton, The Science and Fine Arts of Fasting, pp. 428-433


5. Rare exceptions to this general rule concern people carrying an unusually high toxic load, those whose immune systems are already seriously compromised through another illness, and those whose bodies are already seriously weakened by a pre-existent condition.

12 responses to “Fasting against coronavirus (Covid-19): how to boost immunity and maximize health”

  1. I have been fasting for more than 50 years and am an ardent follower of the writings of Herbert Shelton. I am currently on the sixth day of what I hope to be a 30 day fast. I am now 81 years old and the fasting period becomes harder each year. I feel weaker and my balance is less stable. I have diabetes and hypertension which goes to normal after a few days. I don’t like taking medications so the fast gives me a rest from these medicines.

    I am also fasting to combat the coronavirus. Like you, I believe that fasting does strengthen the immune system even though I feel weaker. I enjoyed your article because it reemphasized what I also believed.

    Paul Fraser

    1. Tallis Barker Ph.D. Avatar
      Tallis Barker Ph.D.

      Hi Paul,

      Thanks for sharing, and congratulations for fasting for as long as I’ve been alive. That’s real inspiration for the rest of us! I’m a fan of Herbert Shelton too – so I’m sure you already know how he discusses that the length of fasting should decrease as we get older. Be kind to yourself and don’t overdo it!

      Wishing you continued health, immunity, and all the best on your 30 day fast,


      1. Marilynn Valenzuela Avatar
        Marilynn Valenzuela

        Hi Tallis, I haven’t read Herbert Shelton, but you mention that he says that the length of fasting should decrease as we grow older. I am 62 yrs and have never done this before. I am presently on day #9 of what I intend to be a 21 day fast. I feel pretty good. Just a bit weak and so I am resting a lot. What are some signs that one should discontinue a fast?

        1. Tallis Barker Ph.D. Avatar
          Tallis Barker Ph.D.

          Hi Marilynn,
          Herbert Shelton doesn’t prescribe any fixed limitations. It’s more a question of respecting the limitations of your body – in the same way that other forms of physical strength gradually wane as you grow older. So long as you’re feeling pretty good and just a bit weak (to use your words) this is fine. You don’t want to reach the point of feeling totally and chronically exhausted, that’s all. Exhaustion is also a natural part of detox, so it might be difficult to recognise the difference between the two. The more you fast, though, the more you’ll be able to reference your previous fasts to gauge this.
          All the best,

          1. Marilynn Valenzuela Avatar
            Marilynn Valenzuela

            Thank you so very much for your response Tallis. Very helpful. You mention in your article about how a 21 day fast is the most effective for boosting the immune system and establishing maximum ketosis. If you don’t mind, I would love to hear about what it is that happens in the body in those days between say 10-21 that makes such a difference in the healing/regenerating process. Thank you so much!

            1. Tallis Barker Ph.D. Avatar
              Tallis Barker Ph.D.

              Hi Marilynn,

              It takes about 21 days of water fasting for the body to finish generating the maximum possible ketosis. In parallel with this it also takes time for the body to reach its maximum cleansing/healing potential. So anything you do in the last week of a 21-day fast is going to be more powerful than in previous weeks.

              When it comes to dealing with deeper health issues, it often takes a week or two of fasting just to get through the general ‘spring clean’ effect, during which the body focuses on the lifetime accumulation of toxins and general maintenance. Of course, the speed of this depends on toxic load and prior fasting experience. It’s also true that the body doesn’t work just on general cleansing to the total exclusion of deeper issues during the first two weeks of a fast. But no matter how you look at it, the third week of fasting brings a greater opportunity to deal with more underlying health issues, since surface-level cleansing has been largely dealt with by this point.


            2. Marilynn Valenzuela Avatar
              Marilynn Valenzuela

              Thank you so very much for you response Tallis
              . It is very helpful and gives me inspiration as I continue into my last week of my 21 day water fast. 🙏

    2. Marilynn Valenzuela Avatar
      Marilynn Valenzuela

      Wow Paul, over 50 years of fasting! Thank you for sharing your strength and commitment.

  2. Marilynn Valenzuela Avatar
    Marilynn Valenzuela

    Thanks so much for this article! I began a 21 day fast a few days ago by starting out with 1 day dry fast and now am on my 3rd day of water. Feeling weak but very good otherwise. I did a 10 day water fast at this time last year and felt it really made a shift in me, physically and spiritually. I am fasting at this time for 21 days primarily for spiritual reasons partly because of the corona virus scare. I am not so much afraid of contracting it myself, but because I want to add to the solution with focussed prayer and intention for the well-being of all beings. I feel very inwardly connected with my Higher Self and higher guidance during fasting and feel that my body and mind are being cleansed and healed. I am very grateful as well that although I feel weak, I don’t feel to eat. I smell yummy things but it doesn’t connect to going into my body. I am very grateful for this because I have struggled with an eating disorder for much oh my life and although I have been much more in balance in the last years, I still struggle with compulsion with food. Completing a 10 day water fast last year was nothing short of a miracle for me. I felt a lot of grace through it the whole time. Thank you so much Tallis for your website and videos, I benefit a lot from your experience and information.

    1. Tallis Barker Ph.D. Avatar
      Tallis Barker Ph.D.

      Hi Marilynn,
      Thanks for sharing. It sounds like fasting has been a truly empowering experience for you – which is actually something I’m writing about in an upcoming past. The way the whole world has gone into lockdown lately has been extremely DIS-empowering for so many people. When you reduce life to its bare essentials through fasting and realise you can survive (and perhaps even thrive), this puts everything else – including lockdown – into perspective…
      Wishing you all the best on your journey,

  3. Thank you for this well expressed article. I have been fasting since 2014. I have experimented with several extreme fasting methods and coached many people as well. I fully stand by this article and through my own experience vouch it to be the same as yours!

    There is a lot of lies being spread about fasting now that its popular and the book worms are perpetuating these lies with out actually having any long term experience. I’ve come to realize the Alphabet mixed with confidence can be a very dangerous thing. Knowledge is gained from the experience of truth and everything else is belief.

    Fasting works.
    This article is correct
    This author is experienced.

    1. Tallis Barker Ph.D. Avatar
      Tallis Barker Ph.D.

      Hi Zito,
      Thanks for sharing your support of this article. I totally agree with your words: ‘knowledge is gained from the experience of truth’. I usually follow this with the words: ‘everything else is just theory’ – but ‘belief’ works equally well!
      All the best,

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