A science-based guide on how to prepare for a water fast (with two actionable strategies)

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Updated on November 20, 2020
Medically reviewed by Daniela Svetic, DMD

Welcome to my science-based guide that includes a couple of strategies on how to prepare for a water fast.

After reading my guide all the way through, you will be in a much better position to decide whether or not water fasting is something you should get yourself into.

We will also turn to science for answers on whether or not a colon cleanse is necessary before or during a water fast.

And like I said, I will finish the guide with two actionable strategies, that will help prepare both your mind and your body for water fasting.

Before we get started, here's a short overview of what's covered in this part of the guide (use it for faster navigation):

How important is it to prepare?

Well, it depends.

If you're one of those people who can eat a normal diet one day, and then easily stay away from food the next day, you can probably do a water fast without any preparations.

But for most people, there is a good chance they will end up stuffing their faces with just about any fattening junk they can get their hands on, after days (if not hours) of struggling to complete a water fast.

If you find what you just read highly relatable, then water fasting probably isn't for you.

Seriously, if you don't feel reasonably confident that you can go without food for a couple of days, then water fasting will probably do more harm than good.

But if you think you can pull it off, then you'd probably still do yourself a favor by planning a smart transition into a water fast.

Taking a little time to properly prepare for a water fast will boost your chances of actually sticking to a water fast for as long as you decide to.

But before we take a look at a couple of options on how to transition into your next water fast, we need to get one stubborn myth out of the way.

Do you need a colon cleanse?

One of the first things people seem to learn in the water fasting community, is that you need a colon cleanse to prepare for a water fast.

Or that at least, you need to do a colon cleanse after you've already fasted for a couple of days.

This crazy idea is based on an ancient theory of "autointoxication".

You see, Physicians in ancient Egypt believed that undigested food should not stay in your digestive tract for too long, or the bacteria in your colon will start producing too many toxins.

During water fasting, those unknown and yet to be discovered toxins are supposed to be absorbed back into your bloodstream, which could supposedly poison or "disease" your body.

Modern science, on the other hand, has found absolutely no evidence to support this ancient and far-fetched theory of autointoxication[1].

The only thing that's actually been proven, are the many health complications that CAN be caused by some colon cleansing procedures on the market today.

Some of those risks include electrolyte imbalances[2] and water intoxication[3].

Other side effects include nausea, diarrhea, and nervous disturbances[4].

Since no evidence supports the idea of having to do a colon cleanse before or during a water fast (while plenty of evidence exists that colon cleansing procedures CAN be dangerous), the bottom line is this:

DO NOT do a colon cleanse to prepare for a water fast (or during a water fast).

And to really hammer this in, you should know that I personally read through dozens of scientific studies on water fasting.

And not a single one of them used any kind of colon cleansing before or during a water fast.

Want to guess what happened?

Not a single person in those studies suffered from autointoxication, self-poisoning, or any similar problems that can only be found in the water fasting communities.

If the medical professionals who conducted water fasting studies felt a colon cleanse is not necessary to prepare for a water fast, then that's good enough for me.

In other words, as far as modern science is concerned, you can start a water fast without invasive and potentially dangerous colon cleansing procedures.

With unnecessary colon cleansing out of the way, here's one sensible strategy that you can actually use to prepare for a water fast.

Reduce the size of your meals

Like I said, a proper transition into a water fast can make the whole fasting experience way easier on you.

Plus, it can greatly improve your odds of actually sticking to fasting for as long as you decided to.

So one of the strategies of gradually easing into a water fast, is to start reducing the size of your meals before you being your fast.

How will this help you?

If you eat smaller meals than you used to, your stomach will already shrink to a degree.

This means that when you start a water fast, you won't feel that big of a whole in your stomach during the first day or so.

If you do this, both your mind and your stomach will already be better prepared to go completely without food.

You can take your time and gradually decrease your meals sizes over a couple of weeks.

As the bare minimum, I suggest you do it for at least a couple of days before you start a water fast.

On to another useful strategy.

Start with intermittent fasting

You can try using intermittent fasting to prepare for a water fast.

How does intermittent fasting work?

It's simple.

You can kick things off by not eating until 12:00 every day, for example.

As you get closer to your fast, you could ramp it up by going without food till 16:00.

After a few more days, you could stop eating food until 20:00.

If you've never done a water fast before, this will give you an excellent insight into how things will start to feel once you begin your water fast.

If, for example, you're having an incredibly tough time staying away from food until 20:00, then you'll probably need a little more preparation before diving into a full water fast.

With a couple of fasts under my belt, I can tell you that just a few days of intermittent fasting before the real thing can mean the difference between success and failure.

But if you can become fully comfortable with the idea of not eating until 20:00, your mind and your stomach will already be 90% prepared to go completely without food.

Time to wrap things up.

Summary (actionable takeaways)

In this part of my science-based guide to water fasting, we've covered a couple of strategies on how to prepare for a water fast:

  • if you're extremely prone to falling off the wagon (did this keep happening to you on the diets you've tried so far?), then water probably isn't for you...but even if that's not the case, you'd do well to plan a smart transition,
  • modern scientific research has disproven the existence of "autointoxication", thus proving that colon cleansing is not only unnecessary before or during a water fast, but also potentially dangerous,
  • reducing the size of your meals in the weeks or days leading up to a water fast can help prepare both your stomach and your mind for fasting,
  • intermittent fasting is a great introduction to water fasting, because once you feel comfortable with spending most of your days without food, you'll boost your chances of actually pulling of a water fast.

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Rok Sprogar is a NASM Certified Nutrition Coach (NASM-CNC) and a NASM Certified Weight Loss Specialist (NASM-WLS) who has been contributing highly actionable and science-based content to Leanhigh.