The one-day (36-hour) water fast

Dr Tallis Barker, water fasting coach

Most people in the modern world have never gone 24 hours without eating. You too? If so, the one-day (36-hour) water fast is the perfect way to begin your journey into water fasting.

I remember when I did my first one-day water fast. My plan was to eat dinner, then fast through all of the following day, breaking my fast with breakfast on the day after this. This format is ideal for anyone wishing to try out a 36-hour fast.

Psychologically, the experience was hugely challenging. Like most people, I’d hardly ever even skipped a meal in my life, and the idea of not eating anything for a whole day seemed almost inconceivable. Every time my stomach rumbled, it felt like the end of the world: I was going to starve! Of course, logically I knew that I wouldn’t, but the rational mind so easily collapses when your deeper, instinctive emotions emerge from out of the subconscious. By the evening, all I could think about was food… In the end, though, I did it. And so can you. Anyone can survive 36 hours without food!

So why put yourself through such a terrible ordeal 😉 ? (By the way, contrary to my own experience, many people do actually enjoy their first one-day fast, feeling full of energy and without existential worries.)

The benefits of a 36-hour water fast:

There are two reasons to face your fears and reap the benefits of a 36 hour water fast. The first is psychological. Precisely by facing your fears and emerging victorious on the morning following the fast, you become a stronger person. We all have a built-in survival response. By breaking the psychological barrier of no food for a whole day, you’ll find that the next 36-hour fast goes much more smoothly. Equally important, it also then becomes much easier to move on to longer water fasts in which you fully unlock the body’s healing metabolism.

The second reason is physical. At the very least, you give your digestive system a break for a day. It can rest and recuperate. This is hugely beneficial for maintaining health and to prevent aging. Mahatma Gandhi, for instance, used to fast one day every week. Following his assassination at the age of 78, the doctors at his autopsy described how Gandhi’s inner organs looked like those of someone half his age.

Perhaps even more importantly, by fasting for 36 hours you prompt the body to begin unlocking its healing metabolism. This can take place only when the body is burning fat for fuel, in a state otherwise known as ketosis. In everyday life you normally burn carbohydrates, either directly from digested food or from the glycogen stored in your liver. When you stop eating, though, your glycogen stores run out after about 24 hours, and your body must begin switching over to ketosis in order not to run out of energy. (This process is described more fully in the article on the 3-day water fast.) There are two main reasons that you can heal while in ketosis. Firstly, the body stores toxins in fat cells, where they can’t cause damage. Only through ketosis can these toxins (continued below)


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be released and expelled from your body. Secondly, the immune system gains extra energy to repair and replace damaged cells when you stop eating, and the energy normally used for digestion can be used instead for healing.

Beyond the 36-hour water fast:

To complete the switch over to ketosis you need about three days, which is why it’s so important to learn the 3-day water fast at some point. But don’t rush into anything too soon! If you don’t feel ready to fast for three days, keep practising the 36-hour fast. If 36 hours feels too long, then try 24 hours instead. You can begin a 24-hour fast after eating dinner and then break the fast with dinner the next day (lunch to lunch is another option). 24 hours does less to nudge the body into ketosis, but still allows you to benefit by flushing out the toxins accumulated from the air you breathe, the water you drink, the food you eat – not to mention any medications and drugs you take. If a weekly or fortnightly 24-hour fast feels too much, then perhaps you should try intermittent fasting instead. Whatever you do, your body will thank you for it!

Dietary transition and refeeding:

One final note: there’s no need to prepare for a one day fast by changing your eating habits beforehand. Likewise, you don’t have to transition gradually back to eating normally afterwards.


— Facing your ego (click here)
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— Physical and spiritual cleansing (click here)

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  1. Chelsea says

    36 hours is a day and a half first off most people don’t realize they can do 36 hours

    • Tallis Shivantar says

      Yes, Chelsea, it’s all in the mind, whether it comes to 36 hours, 3 days, a week or even longer 🙂

  2. Maha Reddy says

    Hi Tallis,
    I have been doing 36 hour fasting for past one year.. I generally drink only Green Tea during my fasting.. Now I’m thinking of drinking Decaffeinated Coffee also during the fasting. Do you see any downside to this?

    • Tallis Shivantar says

      Hi Maha,
      Decaffeinated coffee has the caffeine taken out of it but the acidity is still there. This will keep your digestive system producing enzymes to try and neutralise it, so instead of giving your digestive system a well earned rest, you’ll be stoking the fires! Green teas don’t do this because they’re not acidic and don’t contain calories. Personally, I’d stick to green tea – or better yet, just plain water!
      Hope this helps,

  3. Cousin Pete says

    Hello Mr. Shivantar: I have done a number of 20 hour water fasts and a few 32 water fasts. I just started an 80 hour water fast last night. I normally take supplements daily[high dose vitamin C; magnesium, vit. A; Vit. D; Vit. E, selenium, kelp extract(iodine)]. Should I continue with some/all of the supplements or stop taking them during the fast?

    Cousin Pete

    • Tallis Shivantar says

      Hello Cousin Pete,

      Thanks for your question and sorry about the slow response. I’m currently fasting myself, and during these periods I’m afraid I quarantine myself from the internet most of the time. To answer your question, there’s normally no need to take any supplements unless you have an urgent medical need to do so (in which case you should discuss this with your doctor). In general, taking supplements only distracts your body from its job while cleansing. There’s no point putting things into your body when you’re trying to detox things out!

      You might check out this article:

      Hope this helps,

      • Cousin Pete says

        Hello Mr. Shivantar: Thanks for responding to my question. My fast went well. I did some more research on your site after asking my question. This the best site I have found for fasting. I plan to do a 32 hour fast 2-4 times/month and a three day fast a 2-3 times/year. I hope that your fast went well.
        Thanks again,
        Cousin Pete

        • Tallis Shivantar says

          Many thanks for your kind words :-). Thanks, my fast is going well, and I’ll be writing a blog article about it after I finish later in the week.

  4. HemantKumar says

    Halo Sir

    Tallis Shivantar

    (1)Thanks for your good work here.
    Since I am working Mon__Friday,,I want to go for water fasting on weekends Sat__Sunday.
    I just cant avoid morning tea,,so can I have atleast morning tea(milk tea ,,without sugar,,but with sugarfree).I dont like green tea and black tea.
    Can I do this above tea//water fasting on all weekends??

    (2)Is it ok to take water fasting once in a week?
    Does it result in slowdown in Metabolism?

    • Tallis Shivantar says

      Hello Kumar,

      Thanks for your questions.

      (1) About morning tea: a lot depends on how much milk you put into your tea. In the end, though, it’s best to avoid any form of milk, firstly because it contains plenty of calories and secondly because milk becomes pretty sticky in the digestive system. Both of these things means that you’re going to spend energy processing the milk instead of cleansing. If you really “need” tea in the morning and don’t like green/black tea, then what about drinking a herbal tea instead?

      (2) It’s perfectly fine to fast once a week. Some people even feel the need to do two 24-hour fasts per week. A lot is going to depend on current exposure to toxins, how much residual toxic build-up there is to cleanse, lifestyle, diet etc. – in other words, there’s no single correct solution.

      Hope this helps to answer your questions,

      • HemantKumar says


        Whether water fasting is good for metabolism or detrimental here.
        Can one take 1 days water fast every week and not affecting metabolism adversely ??

        • Tallis Shivantar says

          Hi Kumar,

          Water fasting is definitely good for metabolism in most cases, but you’d probably want to think about less frequent and longer fasts instead of a weekly 24 hour fast – although almost certainly this will be good for you too!


  5. Sanjeev says

    Hello Tallis,
    I’m 44 years old, 174 cm, 75 kg. Diagnosed with high cholesterol + Hypothyroid in January 2018. Taking Atorvastatin, Ecospirin 75 and Clopidogrel 75 daily at night and Thronorm 12.5 in the morning since last 4 months.
    I have quit Sugar since last 3 weeks and avoiding junk food. I have never done fasting before.
    I have started 36 hours water fasting from y’day night. I took one black tea with lemon in the morning. Took lemon with water and little bit of salt after feeling headache in the afternoon.
    Should I skip heart medicines tonight, as I won’t be having dinner ?
    I’m Vegetarian. Planning to take milk tmrw morning in the breakfast and take only salad, fruits and full cream milk tomorrow to get ketosis benefit ? Any advise please.

    • Tallis Shivantar says

      Hi Sanjeev,
      Thanks for writing. I’m afraid I can’t get into the details of specific medical cases here on this public forum. It’s too easy for other people misunderstand and misapply the information. I’m sure it’s possible for you to continue this fast, but – as with all cases involving prescription drugs – I’d urge you to discuss this first with your doctor.
      Best wishes,

      • Sanjeev says

        Hi tallis,
        I have successfully completed 36 hours. No headache. No energy loss. Regular office work. Regular morning walk, driving. Extending for 1 more day.
        Thanks for inspiring me.

        • Tallis Shivantar says

          Good for you Sanjeev – glad to hear it’s all working out for you!

          • Sanjeev says

            Easily completed 60 hours. Planning for weekly 36 hours.
            Thanks for your inspiration.

            • Tallis Shivantar says


  6. Tallis,
    Hello. I’ve been doing intermittent fasting every day for almost 2 months (16:8, 18:6, 20:4, or OMAD). I have noticed a significant and positive change in my overall mood and energy levels since I have started this fasting journey.
    Today, I am doing my first ever 36-hour fast. I am almost 20 hours into it and I’m feeling good so far. I’ve done a couple 24-hour fasts so I figured 36 hours wouldn’t be that much more difficult.
    A couple blogs and videos I’ve seen recommend adding potassium and/or some sort of natural salt like sea salt or Himalayan pink salt to your drinking water in order to keep your electrolytes from dropping too much during a 36-hour or longer fast.
    What are your thoughts on this? I would think that 36 hours is not long enough for your electrolytes to drop significantly. Despite my thoughts on this, I added 1/4 teaspoon of Himalayan pink salt to my 2 quart drinking jug today.
    Is this something you would recommend?
    Thank you for this website and your information. It is all very inspirational.

    • Hi Grey Celt,
      Thanks for writing. I’m sure you’ll do just fine on your first 36 hour fast.

      To answer your question, you’re absolutely right. There’s no need to take added salt, unless you plan on sweating profusely during this period :-).

      Even during longer fasts there’s no reason to worry, so long as you don’t eat a lot of added salt in everyday life. Under normal circumstances, the body conserves electrolytes wherever possible. But by eating added salt in everyday life, not only do you raise blood pressure, you also train your body to expel excess salt, because it’s absolutely crucial that blood electrolytes remain stable. This means that when you fast, your body continues this habit of expelling salt for a while – even though you’re no longer ingesting any.

      The solution is clear: keep added salt to minimum in your everyday diet. If you do, not only will you maintain better overall health, you won’t need to add salt even during extended fasts lasting several weeks.

      Hope this helps,

      • Tallis,

        Great! That’s what my thinking was on this as well. Thanks for the quick response and the info.

        By the way, I’m 38 hours into my 36-hour fast and I feel GREAT! I woke up this morning and have no desire to eat and I’m full of energy. I’m gonna keep myself busy today and see if I can reach the 48 hour mark. 😊

        Again, thanks for the info and I hope you’re having a fantastic day.


        • Good for you, go for it!
          Hope you make the 48 hours. That in itself is another milestone. In the future, though, once you know you can do 48 hours, it’ll be better to stick either to 36 hour fasts or 3 days. This is because you lose the most muscle on day 2 of a fast. It’s nothing to worry about once or twice, but in the long term it’s better to avoid regular 2 day fasts.

          • Tallis,

            Oh, OK. Thanks for the insight on this. I will remember that.

            I’m currently at 40 hours and still feeling great.

          • Jai says

            Beautiful website. I started fasting and frankly it’s the only thing that has worked … So manybreays of calorie counting gymming almost no use. Though fasting was supremely difficult. I’m 5’6 and was always 81 to 84 KGS in weight…
            Now with 3 days of water fast plus 8:days juice fast plus another 6.5 days water fast , I am now 73 KGS.. I need to get to 65… If only I could do a 10 day fast ID be in the sixties.. But it’s so hard… Hunger pangs and food cravings are killing 🙂 ..
            Want to make it though. Currently I fast for once or twice a week for 24 hours.. Any suggestions ???Thanks a lot again for Ur lovely words ..

            • Tallis Shivantar says

              Hi Jai,
              I’m glad that fasting is working for you, and that you’ve decided to take action to control your weight!
              Just know that all the challenges you mention are psychological/emotional, and not physical. A craving for food is an emotional attraction. Hunger pangs are really the way that you relate emotionally to the sensation of hunger, not the hunger itself. Given that your challenges are psychological/emotional, my suggestion would be to try and change your emotional relationship to fasting, when you feel that things are getting difficult. You can do this by (1) practising mindfulness, (2) doing things to take your mind off the cravings, (3) motivating yourself by reminding yourself of all the reasons that you’re fasting. There’s no one key to success here. It’s a question of applying different techniques in different situations, and constantly being on guard against your ego, when it tries to sabotage what you’ve already accomplished.
              I wish you strength and continued success.
              You can do this!

  7. Francesca says

    Hello, I have been doing intermittent fasting for a little over a month now and I can feel a difference most of the time. I have a long 10 hour most sitting work day. So I fast in the am I get up at 6 and start w a bottle of water right away and cont w water until lunch at 12 or 1:00 and then have a snack in the afternoon and then dinner by 7 and eat nothing after 8:00pm.
    I want to try the water fast but am hesitant on if I can keep up with it.
    Any advise?
    Thanks in advance

    • Hi Francesca,
      Thanks for sharing.
      If you already practise intermittent fasting, I don’t think you’ll find the jump up to a 24-36 hour fast too difficult.
      My only suggestion would be to practise your one-day fast on either a Friday or a Saturday. This will give you the next day to relax (Saturday or Sunday) over the weekend. Most people with experience in intermittent fasting find that their energy levels don’t drop too much through the actual one-day fast itself. The day after, though, your body is focussed on rebuilding its glycogen supply, which you’ve more or less depleted, and as a result you probably won’t have so much energy for running marathons ;-).
      All the best,

  8. Justpeachey says

    I really want to do a water fast. There are 2 people at my job who are doing it. One is @3 days and he is acting like it’s his last day on earth. The other is @ six days and smiling like this is an every day routine for her. I have read article after article and have decided that the benefits are far to great not to begin. My concern is that I am overweight and occasionally my blood sugar drops for no apparent reason. Have never been diagnosed with diabetes. My fasting blood sugar is 96. Is the fact that I am overweight causing these intermittent drops? I want to learn how to eat right so I can control the way my body functions. Help please…

    • Hi Justpeachey,
      Thanks for writing. To determine why your blood sugar occasionally drops, you’d have to be taking your blood sugar levels more or less constantly. Obviously this would be a real pain in the finger 🙂 – and more or less totally impractical. The problem of getting an accurate real time idea of blood sugars is one reason why it’s so hard to assess true hypoglycemia. (There’s good reason to believe that “hypoglycemia” is often just a convenient label, and that in fact it often has more to do with withdrawal symptoms from sugars and caffeine than an actual drop in blood sugar. But that’s a story for another day…)

      But yes, the fact that you’re overweight could be the reason for your intermittent drops in blood sugar. To sort this out – as well as to enjoy a healthier life – the three key elements are diet, exercise and fasting. There’s no reason why you shouldn’t consider fasting just because of these drops. Certainly, fasting is extremely powerful in assisting a long-term stabilisation of metabolic functions, when combined with diet and exercise. If you’re worried about any potential dangers, then start with short fasts and work gradually into longer fasts as you increase your experience.

      All the best,

      • Justpeachey says

        Thank you for your speedy response. I have ( at least for the last 3 weeks) been in the Gym 2 to 3 times weekly doing a combination of cardio and weights.
        I talked to my husband about fasting. He and I decided to start with fasting for 24 hrs , 2x weekly for 2 weeks and then going to 36 hrs ( same time frame)

        • Tallis says

          Good for you both! There’s always more strength in fasting together 🙂

  9. John L. Holloway says

    Hello Tallas,
    Thank you for the support and information–do you recommend distilled or alkaline water? Also how many 36 hour weekly fasts would you do before trying the 3 day fast?
    I have an active work schedule so a 3 day might require some consideration.

    • Hi John,

      In the end, water is water :-). If you can drink it in everyday life, then it’s drinkable now too.

      Of course, there are better types of water than others, so avoiding chlorinated tap water (with all its other pollutants) is a good idea if possible. Other than that, though, I don’t feel like there’s any right or wrong. Different people have different preferences – just don’t let other people let you believe that their preference is ‘right’ and all the others are ‘wrong’ or somehow less healthy. Personally, I go to fetch fresh spring water, but that’s just my preference.

      There’s no need to assign a fixed number of 36-hour fasts before trying a three-day fast. I you wanted, you could even dive straight into a 40-day fast (!). It’s all good for you, whatever you do :-). Unless you have an urgent medical reason to fast for a long time, though, I’d walk before running, in terms of the length of your fast. This will ensure the smoothest possible fasting experience, both physically (in terms of detox symptoms) and emotionally (in terms of anxiety). If I were you, I’d try a three-day fast when it just feels like the ‘right’ thing to do.

      Hope this helps,

      • Daniel Williams says


        I’ve been intermittently water fasting now for a few months(mostly 24hr dinner to dinner fasts around one every week or two);and the occasional FULL DAY NO FOOD,which is, in fact nearer 36 hours,dinner on a Sunday for example,then all day Monday no food and “break-fast”(literally) at say 7am Tuesday morning.

        As well as the 8 kilos weight loss through small portions and fasting every week for a day, and the associated lowering of cholesterol and blood sugar levels and blood pressure (the physical); I thought I’d share with your readers the more subtle,but equally fabulous psychological / emotional benefits that have blossomed over the last 7 months or so of fasting every now and then. No set formula, just as and when my body tells me it would be a good idea!

        I FEEL stronger and more in control of my body and my life. After all, we need food to live, so to do without, albeit for short periods, at first,seems counterintuitive; but it seems to strengthen my resolve and self discipline. By fasting, especially for 36 hours, it has made me feel, there is nothing I can’t achieve (work, home, personal etc). This has been the REAL benefit of occasional fasting – the control one gains over one’s mind and thoughts….. This is at the root of it all for me. The physical benefits are clear and any doctor will tell you calorie restriction can benefit you greatly psysiologically – BUT -its the control you learn to exercise over your mind,for me, has been the Euereka! moment – the lasting, permanent positive life changes fasting can bring.


        Life changing..


        Best medicine for the mind and body I’vr ever come across,bar none.


        Daniel Leon Williams 04/04/1979


  10. Jason Raisbeck says

    Hi I am thinking about doing the 3day water fast at the moment am on 1600 cals a day so once I stop the 3day water fast what should I do should I eat something little first then go back to the 1600 calories a day

    • Hi Jason,
      Yes, that’s right. Just transition back to regular eating as you transitioned into the fast.

  11. This 3 day waterfasting is in my opinion a good reset for foodaddicts like me. In fact I’m doing it right now.. The first day is done. How often do you recommend this to do? Once every month?
    BTW – I’m glad, to have found this page.

    • Hi Klaus,
      Good for you that you’re facing your food addictions!
      I’d recommend doing a three-day fast whenever your body starts to ask you for one. The important thing here is in being able to distinguish the authentic voice of your body from the goal-based voice of your mind and ego, which tend to sound more like: ‘I SHOULD be fasting’. Want, desire, achievement, willpower: these are all things that the body itself doesn’t know, and I’d be very wary of them when you detect them in your inner voice which tells you that you ‘should’ do another fast. ***By the way, this is a problem for a lot of people!***
      When you body tells you to fast it really does feel like it’s coming from the body: a simple urge. In a way, it’s a little analogous to when you have to pee :-). A voice simply emerges from the body announcing itself. In the case of a full bladder, it doesn’t say that you ‘desire’ a pee, or that you should do it regularly every 5.5 hours. Nor do you feel a sense of ‘achievement’ afterwards. You just feel comfortable and cleansed. It’s the same with fasting.
      So… you might find that your body asks for a three-day fast every month, but so long as you’re eating cleanly and don’t already have a high toxic load, it maybe be less than that. It may vary from occasion to occasion. Who knows! Just be sensitive to your body’s needs, and you’ll know what to do 🙂

  12. Louis says

    I’m thinking of starting a 36hr fasting. How long should I practice this for? Like once a week for a month or once a month?

    • Hi Louis,
      It’s up to you. A standard practice is to fast for 36 hours once a week. Some people even go as far as fasting twice a week like this.
      The most important thing, though, is not to take on too much, too frequently, so that it turns into a chore. If you’re new to fasting, I’d suggest aiming for something less frequent at first, and then tune into what your body is telling you. If you don’t feel any resistance, then you can slowly up the frequency until you find what feels right. Maybe this will be once a week. Maybe not. You’ll see.
      All the best,

      • Dan says

        Your waster fasting has been nothing short of a revalation! I’ve been doing one or two 24hr fasts each week with a 36hr fast every 2 or 3 weeks and I’ve lost nearly 2 stones in 4 months; I’ve been trying to loose it for years and nothing worked – until now!
        My BP and HRH have fallen by 20%, my skin is brighter, I have more energy and my doctor has recommended I come off my meds this year!
        This has given me a new lease of life and extended it too accordign to my medical team!
        Thank-you so much.
        Amazing. Life changing.
        Dr Daniel Leon

        • Thanks for sharing, Dan!
          It’s great to hear an inspiring story like this :-)))))
          All best wishes for your continued good health,

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