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Water Fast Week

What’s This Fasting Business All About?

A couple of months ago, Dr. Thomas Seyfried – the author of Cancer as a Metabolic Disease: On the Origin, Management, and Prevention of Cancer – came on the show to speak to us about metabolic fasting as a means of cancer therapy – and (possibly) prevention.

For the more in-depth explanation of how exactly that works, click here to listen to the episode.

The rest of this post will throw around words like ketosis and just assume, you know what that means – so if you don’t, check out Episode #56!

The short version?  It may be that we have the ability to “starve out” stray (pre-tumorous) cancer cells by simply… not eating.  Cancer cells don’t survive nearly as well as healthy cells in a ketotic internal environment.  And the quickest way into ketosis is, well… starving.

Dr. Seyfried cited “a 7-day water fast, once per year” as his recommendation for a healthy person to remain cancer-free by starving any errant cancer cells before they can get a foothold in the body.

This means that for a comparatively small investment of time (and a larger dollop of willpower), we might be able to significantly extend both our lifespans and our “health-spans.”  Cancer remains a distressingly prevalent killer and misery-bringer – so anything to safely lessen its likelihood is great news, right?

Why Water Fast?

While there are many variations on this theme – slightly different fasting methods promoting slightly different health benefits – research suggests that a water-only fast of at least three days is the most effective method to achieve a ketotic body state in the shortest amount of time.

Why a Week?

Three-to-four days to get firmly “into ketosis,” then the rest of the week to give any loose cancer cells in our bodies time to starve.

A day or two shorter might not be enough time to kill the stray cancer cells.  Any longer might be (pardon the pun) overkill.

The Plan

We plan to do a 7-day water-only fast – and if it goes well, it will likely become an annual ritual.

While we’re very set in the belief that the possible-rewards outweigh any expected unpleasantness, we’re also realistic about this being a pretty big undertaking.  (7 days.  Water.  Only.  Ugh.)

So, in an attempt to make the week infinitely less excruciating, and beneficial to as many people as possible, we’ve decided to arm ourselves with as much information as we can.  And in the company of other like-minded, willpower-imbued longevity-seekers.

And so, Water Fast Week was born.

From February 16th-22nd, everyone participating will be communicating via an online forum, sharing their personal experiences, tips, and helpful information with the group.  We’ll have a few experienced fasters – as well as a medical doctor – in our midst, to chip in where they can as well.

And, almost certainly, we’ll cover the action* in a Smart Drug Smarts episode.

* “Action” might not be the right term; we’re expecting a pretty lethargic week.


  1. caleb says:

    You can also quite easily enter ketosis on a mere carb fast. I am regularly able to enter ketosis after feasting on meat and eggs and veggies for 3-4 days (confirmed by testing with ketostix). Not sure if you’ll kill the cancer, but in that case you’re looking for a different word than “ketotic state”.

    1. Jesse Lawler says:

      Yeah, the Water Fast was merely recommended by Dr. Seyfried as a time-effective way to get into deep ketosis fast. Continuing to eat a super-carb-reduced diet and waiting for one’s glucose and glycogen stores to slowly deplete would eventually get a person to the same end-point. (And possibly with a lot less inconvenience.)

  2. matthew says:

    Great question to ask him is what effect would fasting have on neuroplasticity?

    1. Jesse Lawler says:

      I suspect the answer here would be the same as “what is the effect ketosis has on neuroplasticity?” as fasting for more than a few days is a slingshot into ketosis. I’m not sure the answer to that exact question, but the anecdotal reports of “mental clarity” from long-term ketogenic-diet people are quite positive. Don’t be surprised if we have another ketosis-and-the-brain episode in the future, as this seems to be an area a lot of people (myself included) are interested in.

  3. erasmus says:

    Are you also planning on doing the Salt Water Flush? Also when you are done and you do start eating again. You will get very sick if you eat a lot and don’t take it very slow. I would start with something like yogurt if I was to try it again. You might get sick either way. Good Luck!!!

    1. Jesse Lawler says:

      I was considering a salt water flush on Day 2 or 3 to “push anything still inside, out” so I don’t have food on a stopped conveyor-belt inside me for another 5 days… However, I haven’t yet researched the overall healthiness of a salt water flush. I’ve heard mixed things. As for re-starting the eating process with baby steps, absolutely yes.

  4. ben says:

    I understand it takes a few days of low carb (<20g) before the brain switches to burning ketones, but how do you know when this happens? Do most people just feel it, or are they using urine test strips?

    For years, aside from coffee in the morning, I only consume calories at dinner… but I'd like to try a full 7 day fluid-fast. All the warnings I've read seem to be related to maintaining proper blood pressure, so instead of water, my only adaptation would be to use a Ca, K, Mg, NaCl broth cocktail.

    Finally, Chris Masterjohn, has a great podcast that suggests using MCT oil can be as effective in generating ketones as restricting carbs.

  5. David says:

    When is it 2018?

    1. Alexa Magnon says:

      Hi David!

      The 2018 Water Fast Week took place in May, but Jesse is thinking about hosting a second one later this year. You can sign-up to get notified the next time there is a water fast coming up at Smart Drug Smarts Water Fast!

      Have a great summer!


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