The three-day water fast

Of all fasts, the 3 day water fast is in many ways the most important. Three days is the period your body needs to unlock your healing metabolism and begin reaping the benefits. These three days are also the stepping stone for moving on to longer fasts (such as the 7-10 day water fast and more prolonged fasts), in which much deeper healing can occur. The more you practise the 3-day fast, the easier you’ll find water fasting of any length.

I’ll be honest with you, though. In the beginning, the 3 day water fast is also often the hardest.

Because of this, it’s important to do everything you can do to maximise your chances of a smooth experience. This can include following a well laid-out plan, such as that found in my 3-day water fast Online Course. For those who need more personal contact, I also offer online consultations and coaching.

Whether you choose support or to go it alone, it’s definitely better not to try and bite off more than you can chew 🙂 with a 3-day fast until you feel comfortable with one-day (36-hour) water fasts. This is because a 3-day fast really is a quantum leap ahead in terms of what it demands from your body.

What are the challenges and benefits of a 3-day water fast?

Before you gain greater experience, most of the challenges of the three-day water fast are physical, as your body learns how to enter the state of ketosis. Ketosis is the metabolic process of burning fat mobilised from adipose (fat) tissue in the form of ketones and fatty acids. Unless you happen to be following an extremely low-carb diet, this is entirely different from how your body normally extracts the energy needed to power each cell. As a result, the vast majority of people never experience ketosis in everyday life, and rely instead on metabolising carbohydrates until the day they die. This is a real shame. We have two eyes, and we use them both. We have two arms and two legs, and we use each of them. We also have two metabolisms: our everyday carbohydrate-based metabolism, as well as ketosis. They each serve their own function and offer their own benefits.

There are two huge benefits of getting into ketosis while you fast.
First, because you’re burning fat and not eating/digesting, your body frees up a lot of extra energy for healing. (It’s estimated that digestion accounts for about 30% of your total daily energy needs.) However, unless your body has a lot of fat that it’s happy to burn, you probably won’t feel this energy going out into everyday strength and stamina. Instead, your body is more likely to want to turn it inward for detoxing – which can easily leave you feeling weak and drained on the outside.

Second, because you’re drawing on the fuel in your fat cells, you also gain the potential to break down and cleanse the fat-soluble toxins which have been locked in there for years and years, safely sequestered away from interacting with the rest of your body. This is a different mechanism from being on a low-carb diet, because in this case essentially the same surface-level fat cells are used for energy, over and over, from meal to meal. In contrast, deeper levels of fat usually remain untouched, with the toxins of life continuing to accumulate within. This is reflected by comparing the ketone levels of someone on a low-carb diet with those of someone on a water fast. Not surprisingly, ketone levels while fasting are much, much stronger!

What happens on a 3-day water fast, day by day?

Day 1:

On a purely physical level, the first day obviously feels the same as it does on a one-day fast (described in greater detail here): as you slowly exhaust your reserves of carbohydrates, which are stored as glycogen mostly in the liver, as well as in the tissue surrounding your muscles. Psychologically, though, if you already have experience in surviving one day without food, you should feel much more comfortable. Surviving three days without food is simply an extension of this, and so hopefully you’ll be freer to concentrate on the physical changes taking place inside your body. You may indeed find yourself facing your ego over these three days, but it’s more likely to take the form of facing your addictions to food rather than facing your ego’s existential fear for survival (as can happen the first time you fast for 24 hours).

Day 2:

By the beginning of the second day your glycogen reserves will have run out. At this point, how you feel depends on how much experience you have in fasting. Nowadays when I fast, I feel great because my body has made the switch to ketosis in tandem with my glycogen stores running out. In other words, I don’t suffer any ‘power loss’. In fact, I usually benefit from even fuller energy towards the end of the first day because I’m powered by two sources: the remains of my usual carbohydrate-based metabolism, as well as by ketosis – which starts to kick in a couple of hours after I miss my first meal. It’s a great feeling, and, in time, you can look forward to it too!


Complete a 3-day water fast

This video + pdf bundle provides you with all you need to know in order to safely, successfully and smoothly carry out your first 3-day water fast. If you already have a little experience, there are plenty of additional tips to help you go deeper into water fasting.

However, if your body isn’t adapted to ketosis, things will probably be rather different… Your glycogen fuel tanks will hit empty, and your body will have to search for an alternative power source – and quickly too! The burning of fat through ketosis is highly efficient, but the problem is that your body hasn’t yet learned how to easily access this metabolism, because the biochemical reactions and hormonal parameters which mediate those reactions are so different from what you’re normally used to. Instead, following the depletion of glycogen, the next closest source of energy is through burning the building blocks of protein – and this comes from metabolising amino acids. Primarily, this takes place in the liver through a process called gluconeogenesis.

Although all cells across the body contribute amino acids towards gluconeogenesis, it’s true that muscle cells generally store more amino acids than other types of cells. But don’t worry: contrary to a lot of well intentioned but misinformed information out there on the internet, this doesn’t mean that you’re going to lose any significant muscle mass. Rather, we’re only talking about the loss of amino acids – not the actual autophagy of muscle cells themselves. Besides this, once your body has started to perfect ketosis in the coming days, the continued need to metabolise proteins becomes increasingly minimal.

In the meantime, you’ll probably continue to feel low on energy. Your muscles may ache, especially in your legs and glutes. Headaches are also common, both from low blood sugar and lack of energy, as well as from the beginnings of detoxification. Dull aches around the lower back are also common, as your kidneys and lymphatic system start to work overtime, flushing out the first toxins from your fat cells as well as the extra acids caused by metabolising protein. All of this can be enough to elicit nausea as well. In the face of such detox symptoms, make sure you’re drinking enough: at least a quart/litre or two per day. There is no fixed minimal limit to drink. This depends mostly on a person’s level of toxicity. The higher the toxicity, the more you’ll have to drink. Many people drink 3-4 quarts/litres a day.

I don’t want to lie to you. Personally, I feel that too many books and websites on fasting paint a rosy-coloured picture of how you’ll feel. Telling the full truth might turn off potential converts to water fasting… Yes, perhaps you’ll feel like a million bucks. But for the first couple of three-day water fasts it’s more likely that you’ll feel pretty awful, not entirely dissimilar to how you experience the flu: with aches and pains, and a general lack of energy. But don’t worry. And don’t give up at this point!!! You’ll survive. Just hang in there. All these symptoms will pass.

Day 3:

The third day is more or less a continuation of the second, both in terms of the physiological processes taking place, as well as how you feel. Many people feel at their lowest at the end of the second or at the beginning of the third day. Generally, though, things start to improve after this, as the switch to ketosis is completed.

If the toughest part of a fast is getting through the first three days, then isn’t it worth diving straight into a longer fast and reaping the benefits of what you’ve suffered through? Maybe. If you have the energy to do so, then by all means! Most likely, though, your first few three-day fasts will leave you feeling drained both physically and emotionally. There’s no need to do any more at this point. Three days is enough. Mission accomplished. You’ve successfully awoken your body’s healing metabolism, which you’ll be able to rely on increasingly in the future. You’ve also already experienced a significant degree of detox. Instead, I’d recommend taking on a longer, more cleansing fast once your body and mind have more fully acclimatised to and made friends with three-day fasts. The most important thing here is to build up a stable, positive, long-term relationship with fasting. There’s no need to rush ahead, unless you have an urgent health issue which requires a more extended fast immediately.


At the end of the third day, enjoy a glass of freshly squeezed orange juice and pat yourself on the back. Unlike longer fasts, there’s no need for a long transition back to eating. Nor is there any need for a long transition before the fast itself. However, do keep the first few meals light: mostly just fruits and/or vegetables (just as the last few meals before the fast should also be light). Don’t eat too much! If your ego is telling you to gorge yourself, avoid the temptation and try to honestly follow your appetite. Your stomach will have shrunk, your digestive system will have slowed down considerably, so you need a little time to get things up and running again. If you do follow your appetite, you’ll find you’re eating normally again within a day or two.

After breaking a longer fast, though, it’s extremely important to follow a well structured meal plan.

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.

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353 responses to “The three-day water fast”

  1. Thank you so much! I have done a 3-day fast where I had so much pain and aches on my back and legs. I am fairly young in my 30s and never had back problems it felt like muscle aches. Your article explains it all, now it all makes sense! I do have an autoimmune condition so I’m hoping to dive in to longer fasts once I get to experience 3-day fasts without these muscle pains. Thank you again, such valuable info!

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

      Hi Anabel,
      Thanks for sharing. Glad this article helped :-). Yes, autoimmune conditions will certainly require a significantly longer fast, but I’ve seen so many people heal through fasting, that you should definitely feel optimistic about a long-term improvement! If you need coaching to optimise the efficacy of a longer fast, feel free to reach out.
      All the best,

  2. Tearra 🌹 Blankinship Avatar
    Tearra 🌹 Blankinship

    Thank You So Much for sharing your insight & wisdom! God Bless You 🤍🙌💪

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

      Hi Tearra,
      Thank you 🙂

  3. Dale Kormazis Avatar

    Question, I have celiac disease, I feel a 3 day water fast, perhaps monthly would be of great benefit. Your thoughts on this.

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

      Hi Dale,
      3-day water fasts may eventually start to heal celiac disease, but even in the most optimistic scenario it will take many months if not longer. Serious gut issues like this generally respond much more effectively to longer fasts. You might see improvement from 7 days onwards, and you can expect more reliable results from 14-21 days and longer. 3 days is an important stepping stone towards providing the confidence you’d need in contemplating a much longer fast.
      Hope this helps,

      1. I am wishing to heal severe GERD by water fasting. What would you recommend? Starting with 3day- and how often after? 3days a week for how long?

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

          Hi Em,
          Thanks for writing. Water fasting (as well as dry fasting) can be extremely powerful in healing GERD. It’s hard to suggest an exact protocol without knowing more details about your specific case, but if you feel comfortable with 3 days, give it a go and see where it takes you!
          All the best,

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