The one-day (36-hour) water fast

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)

Check out the webshop on

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

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.

Related articles:

If you enjoyed this article, please share on social media, using one of the buttons below:

141 responses to “The one-day (36-hour) water fast”

  1. I am trying my best to do a 72 hour water fast. I am currently at 39 hours. I am on meds for my prostate, one pill in the morning and one at night. Is that going to affect the benefits of water fasting in any way? Are there any dangers in doing this?

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

      Hi Ron,
      Thanks for sharing. Good for you, aiming for a 72-hour fast!
      To answer your question: adjusting the dosage for meds – which can mean anything from keeping them the same, reducing them, or eliminating them entirely – totally depends on the individual drug in combination with the length of a fast. In a public space like this, I can’t advise you on the specifics of what to do in your case. In general, though, it’s best to keep taking many meds without any recalibration for one-day fasts. On 3-day fasts, you need to consider the half-life of the drug, how quickly it acts and metabolises, and any repercussions of coming off it, including any potential withdrawal symptoms. Many anti-inflammatory drugs can be calibrated down as the fast’s own anti-inflammatory effects kick in, but this too is only a generalisation. The simplest thing at this point is to ask your doctor.
      Hope this helps,

Leave a Reply

This site uses Akismet to reduce spam. Learn how your comment data is processed.