Water Fast Coaching and Articles

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

3-day water fasts: cleansing, ketosis and metabolic change explained

Expert Water fasting coaching with Dr Tallis Barker? D.Phil, Nat.Dip

Your first 3-day water fast is a major step into therapeutic fasting. It’s the point where your body begins shifting from sugar-burning to ketosis, awakening your natural healing metabolism. But it’s also where most first-time fasters meet their biggest challenges—both physically and emotionally.

If you’re new to this, you might have some immediate questions. Here are quick answers to the most common ones:

Your body switches from burning sugar to burning fat (ketosis), triggering healing and detox. This usually starts after 36–48 hours.

Glycogen runs out, but full fat-burning hasn’t kicked in yet. This “in-between” phase can cause fatigue, aches, or low energy.

Only minimally. The body uses amino acids briefly, but not whole muscle tissue—and once ketosis is established, this stops.

Headaches, body aches, nausea, and fatigue—especially around the lower back—are all normal. They pass as your body adjusts.

Start gently with juice, then light fruits or vegetables. Don’t overeat—your digestion needs a slow restart.

CONTENTS:

Introduction
Why the 3-day water fast is your gateway into therapeutic fasting and how it unlocks your healing metabolism.

Benefits and Challenges of a 3-Day Water Fast
How your body shifts into ketosis, why this matters for detox and energy, and what makes the first few fasts especially demanding.

What Happens During a 3-Day Water Fast – Day by Day
A detailed guide to the physical and emotional changes of each fasting day, with practical insights to support your experience.

  • Day 1: Easing In
    Glycogen depletion begins; emotional resistance may soften if you’ve fasted before.
  • Day 2: Metabolic Crossover
    Glycogen runs out, ketosis begins—but symptoms like fatigue, aches, and detox may peak here.
  • Day 3: Turning the Corner
    Ketosis stabilizes, energy may start to return, and the healing metabolism is now fully active.

Refeeding After a 3-Day Fast
How to break your fast safely with light meals, avoid common pitfalls, and support digestion as you return to eating.

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Introduction:

On the journey into water fasting, your first 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.

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.

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 benefits and challenges 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. (And even if you do follow the lowest possible carb diet – which in most cases is certainly not advisable – the depth of fasting ketosis far exceeds that of dietary ketosis.)

In short, the vast majority of people never experience deep 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 cleansing and detox – 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 24 hour fast (described in greater detail here). During this period 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).

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

Day 2:

By the beginning of the second day your glycogen reserves will almost certainly 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 fasting 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!

ONLINE COURSE

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! Ultimately, 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 within the first 24-36 hours of a fast, the next closest source of energy is found by breaking down the building blocks of protein. This comes from metabolising amino acids. By stripping off the nitrogen molecules common to all amino acids it is possible to synthesise glucose, which can then be burned in the usual way within the mitochondria of each cell. This process of converting amino acids to glucose takes place primarily in the liver through a process called gluconeogenesis.

Although all cells across the body contribute the amino acids necessary for 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 talking about the loss of only amino acids – not the actual autophagy of whole muscle cells. And in any case, once your body has started to perfect ketosis in the days ahead, 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 – and especially if you have the mental energy to do so – then by all means continue your fast! 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 3 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.

Refeeding:

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.

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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386 responses to “3-day water fasts: cleansing, ketosis and metabolic change explained”

  1. Hey Tallis,
    I recently completed a three day dry fast without ever having undertaken a water only. Other than weight loss, a slight headache and a little lethargy I felt no real detox symptoms. No coated tongue, nothing, and I’m not exactly an advertisement for healthy living. To be honest, I felt the whole thing a waste of time. I certainly didn’t get anywhere near ketosis. On the third day I wasn’t even hungry although I was beginning to get thirsty. Could it be possible, that by neglecting the water only, my body somehow didn’t properly enter into detox.

    1. Hi Thomas,
      Thanks for sharing your experiences. I’m glad it all went so smoothly for you :-).

      Now about it all being “a waste of time”: just because you didn’t suffer through the fast doesn’t mean it wasn’t working. I’ve led smokers, drinkers and other people who likewise aren’t an advertisement for healthy living through three-day fasts, and quite often they too describe the experience similarly to yourself. So much of the way people experience physical symptoms is influenced by their emotional state of being. I suspect you didn’t go into the fast with a lot of fears, and that in everyday life you’re a pretty laid-back guy. Would you agree with this?

      About not getting “anywhere near ketosis”: unless you’re a superhuman who can store 72 hours worth of glycogen, you most certainly WERE in ketosis! It’s a simple matter of biology. After 24-36 hours we all run out of glycogen. Period. The only thing is that your transition into ketosis went really smoothly and you hardly even noticed that it was happening. That’s something to be happy about!!! – because for a lot of people it doesn’t go so easily.

      Instead of being a superhuman who can store 72 hours worth of glycogen, I’d suggest that your superhuman-ness 🙂 manifests through a natural talent for fasting.

      Besides this, the thirst on the third day was most likely the result of detox, not the absence of it. Detox often makes you thirsty: your body’s language to tell you to drink in order to help flush out toxins.

      If you still feel that the 3-day fast was a waste of time, then why not try something a little longer next time?…
      Consider yourself lucky and, yes, naturally gifted in your ability to fast. That’s great!
      All the best,
      Tallis

      1. Hey Tallis, Thanks for taking the time to reply. I have a holiday coming up, so I’m going to try again. Good luck, Thomas.

  2. I take Levothyroxine for my thyroid. Do I still take it while doing the fasting?

    1. Hi Jaime,
      I’m afraid I can’t answer questions here in the comments about specific cases, drugs and dosages. To do so would be irresponsible. You should discuss this with a doctor who is familiar with fasting and who knows all the details of your case.
      Tallis

  3. During the fast can you squeeze fresh lemon juice into your water? Or does it need to be just stright water the whole time?

    1. Hi Corpse,

      It depends what you mean by “need”. If you mean: “will the occasional slice of lemon disturb ketosis?”, then the answer is no. But there are also other potential factors to consider. You’ll find more in this recent blog article about taking supplements while fasting:

      https://waterfasting.org/2017/12/03/pills-powders-and-potions-the-reality-of-taking-supplements-while-fasting/

      Hope this helps,
      Tallis

  4. Hi I have started a 3 day water fast I’m on day 2 though I still have straight black coffee in the morning (due to migraines I need the caffeine). I’ve had a headache most of the day but I’m sticking it out. I have high blood pressure and want to start healing my body so I can come off the meds. Do you have any advice for me? Thanks

    1. Hi Cara,

      Thanks for sharing.
      My best advice to you is to come off the coffee while fasting. In any case, I’d always recommend drinking green tea over coffee while fasting, because it’s less acidic and won’t stimulate your digestion. But in order to use fasting as an modality to heal high blood pressure, you need to get off the caffeine completely while fasting, as it will artificially raise your BP precisely when you want the fast to be lowering it.

      I’d suggest gradually lowering your caffeine intake before your next fast so that you won’t suffer headaches during the fast itself. Then you’ll be free to fast without taking caffeine. A three-day fast is a good place to start in terms of healing high BP, but in order to effect permanent change, you’ll need to fast for a longer period of time.

      All the best,
      Tallis

  5. I have read that you should fast if you feel the beginning stages of a cold or flu. Can you corroborate this?

    1. Hi,

      This is what I always do myself. Consequently, I haven’t succumbed to a cold or flu in several years now.
      However, I don’t think it’s quite as simple to say that it will always work for everyone.

      When I first started fasting, sometimes it worked and sometimes it didn’t. Over the years, fasting to prevent illness has become much more reliable for me – something I believe has two main reasons. First, I’m much more cleansed physically now, so the energy of my fast can go more efficiently to combating the pathogen instead of general detox. Second, I’ve become totally at home with fasting, so that the idea of not eating is (almost) as normal as the idea of eating. In other words, I don’t have emotional resistance against or anxiety about fasting. Again, this means that I’m not wasting any energy on anything besides fighting the pathogen.

      My advice to you is to try it out and see what happens. (At first you may even find that fasting seems to make the symptoms worse, so don’t be alarmed.) For it to become truly effective, though, you need to fast regularly when you’re healthy.

      Hope this helps,
      Tallis

  6. Do you still take supplements during the fasting time or just water with no supplements? Thank you.

    1. Hi Ruth,

      Well, your question is a little vague… 🙂
      Can I suggest reading this article first?

      https://waterfasting.org/2017/12/03/pills-powders-and-potions-the-reality-of-taking-supplements-while-fasting/

      Tallis

  7. Hi Tallis. I’m riddled with rheumatoid arthritis at the moment. I switched to a plant based diet on 1 January this year as I’ve heard so many people have had success with this. Unfortunately I feel even worse and my RA at the moment is out of control. I read that water fasts can be really beneficial for helping to kick start the healing process. Have you had anybody with my condition that has had success with water fasting and RA?
    Many thanks
    Toni

    1. Hi Toni,
      Sorry to hear about your RA. I don’t have experience of coaching anyone specifically with RA, but those I’ve worked with who suffer from other joint and swelling issues have all responded favourably to water fasting. You’ll want to consider how to approach water fasting in terms of the length and frequency of the fast(s), as this will affect how your body responds.
      All the best,
      Tallis

      1. Hi Toni and Tallis,

        I’ve just completed a 95 hour fast. I also have ra and fasted for that reason. I found joint pain decreased throughout and my energy levels were better by day 3. I didn’t really want to go back to eating because of this, but being my first fast I thought I should.

        I’m currently day 2 post fast and had some morning stiffness in hands (that had disappeared by day 3) and my shoulders are marginally less mobile. Clearly my elimination diet needs work.

        Thank you for this site and your answers you provide to questions and comments. This gave me the info I needed to try. I actually came back to the site today to find out how long before I could fast again. The next comment answers that quite nicely.

        Thanks to Tallis and good luck to Toni.
        Michelle

        1. Hi Michelle,
          Thanks for sharing. Glad you began to see the benefits of how water fasting might help your condition. Of course, to see more significant healing of RA, you’ll need to fast for considerably longer, but I hope what you’ve already experienced this time around will give you the resolve to continue in the future.
          Best wishes,
          Tallis

        2. Thanks Tallis and Michelle for your kind reply. How’s your pain doing now Michelle? I really paired back my diet and gradually things improved but I’m away at the moment visiting family and it’s very hard to be as basic as I need to be. After looking at another site of a Dr Klaper, who also recommends water fasting, he mentions that after the fast RA sufferers should follow the Paddison Programme. Clint Paddison is an Australian guy who completely reversed his RA, the diet is strict and difficult to stick to but it’s all about healing the gut and getting your gut microbiome back to full swing. It took him a while to do it but he got there in the end. His program has helped many to get back their health. Hope this is ok to post!
          Kind regards
          Toni

  8. How often would you recommend a three day water fast? I have read that it is most commonly done every three months. Do many people do it monthly?

    1. Hi Gretchen,

      What I would recommend is trying to get away from arbitrary frequencies like three months or monthly. It’s natural to think in terms of set times, but fasting should come from a deeper voice within – not the one in your head which knows how to tell time! As you gain more experience with fasting, you’ll know when it’s time, when your body is asking for a fast.

      If you’re not listening, though, fasting can all too easily turn into a mere routine, rather than something which brings us closer Us.

      The only fast which I’d normally recommend practising at regular intervals is a daily intermittent fast or a weekly 24/36 hour fast, because in order to get to the point of feeling like 3+ days are comfortably manageable, most people do have to practise shorter fasts first. And practice means repeating something at regular intervals :-).

      After that, though, the best way you can honour your body is by being sensitive and actually listening to it, rather than holding it to the clock.

      To answer your question, you can certainly do a 3 day fast monthly if you feel the calling. I’m even working with someone right now who does it weekly in order to manage a serious illness. Anything is possible, but I’d urge you to listen to your own authentic inner voice instead of the voices of what others might say.

      Here’s to your health,
      Tallis

  9. Great article! I’m on the first 24 hrs of my fasting. Excited to keep on going!

    1. Good for you, Fabiola, go for it!
      Tallis

  10. LaTonya Colbert Avatar

    So I tried the water fast and lasted 4 1/2 days, my job is pretty physical on average I walk 4.5 to 5 miles around 10,000-11,000 steps. I want to last longer so that I get more of the health benefits but I was getting weak, lightheaded, nauseous etc. I’m wondering if any one else has a physically demanding job, if so how do you manage the symptoms or any other advice well appreciated thanks. Or maybe just keep building up to a longer fast?

    1. Hi LaTonya,
      Thanks for writing. In principle there should be no problem with walking 4-5 miles a day while fasting. In fact, it’s a great way to deal with any detox symptoms. The important thing, though, is not to push yourself too hard while you’re doing your 10,000 steps. Is there any way you can walk slower? If you can, I suspect the weakness and lightheadedness will abate. If, on the other hand, you have to keep up with your regular tempo, I’m afraid it’s going to be a rough ride. It’s a simple biological fact :-(.
      If you have to work while fasting, then maybe it’s worth considering shorter, more frequent fasts. It’s true they’re not as effective as longer ones, but over time you’ll still reap a huge benefit from them.
      Congratulations on your 4 1/2 days – that in itself is a great achievement!
      Tallis

  11. Thanks for this supportive educating article.
    I am on Day 2 and 1/2 and you helped me decide to hold off food for another 12 hours.
    I am feeling great. My wife makes Ginger Water, that’s all I’ve been drinking for 2 days.
    It feels great.

    1. Good for you! Glad you’ve felt the strength to keep going, and glad you’re feeling great too.
      Thanks for sharing 🙂
      Tallis

  12. Hi Tallis! I just discovered this water fasting thing and decided to try it out due to my acne. Do you think it will be effective to cure acne too?

    1. Hi Charm,

      Yes, this water fasting thing can definitely help. Fasting is renowned for improving skin quality, because the skin is one of the major organs of cleansing, and fasting rejuvenates it. One way of looking at acne is to think of it as skin which can no longer successfully do its job in terms of detox. The toxins pile up in your skin and cause spots.

      However, it’s also important to be realistic: realistic in terms of improvement, as well as in terms of what kind of fast you can comfortably manage. If you’re new to fasting, then I’d suggest beginning with short but regular fasts. Try a few 36 hour fasts. You won’t see a huge improvement overnight, but with regular practice things will begin to improve. Once you feel comfortable with 36 hours, you can start to increase the length of your fasts. But be under no illusions: to get to the point of a single fast having an immediate effect on your skin quality, you’d need to fast for at least a week.

      Equally important to fasting is diet. It’s not enough just to get rid of all the “bad stuff” inside you. If, through an unhealthy diet, you continue to reload your body with toxins, any benefits from fasting will quickly disappear. You probably already know that you should eliminate as much meat and dairy from your diet as possible. A strict vegan diet is going to be the best from your skin – and certainly at least while you work through your acne. If you end up moving in this direction, though, you need to be extremely careful that you’re getting all your nutrients.

      All the best,
      Tallis

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