Five-Day Water Fast: Fasting is an extremely powerful healing modality that we continue to delve deeper into as the science keeps on supporting its benefits. Today we explore the general things most people experience and what is happening inside the body day by day for a five-day water fast.
Five-Day Water Fast: Nature’s Therapeutic Mechanism
Oftentimes the most powerful thing a doctor can do to help heal you is nothing. Fasting is indeed an ancient healing modality linked to every religion and culture across the globe. Animals do it when they’re sick for the same reasons humans should: the body has an innate healing intelligence. The benefits we discuss below generally require a five-day water fast or a five-day fasting-mimicking diet. Although the benefits of shorter fasting, or intermittent fasting, are still good, the body transitions into fat-adaptation usually around day three. So, give it five whole days.
To understand how fasting works, let’s explore the seven bodily effects of fasting.
Five-Day Water Fast: Day One
If you’ve adequately prepared for a 5-day water fast, which you can learn all about in my book Beyond Fasting, then day one generally is relatively easy. Prior to taking on a five day fast, it’s a good idea to get into intermittent fasting, as well as diet variation that will incorporate 24-hour fasts into your weekly eating cycles.
If you haven’t prepared, day one can be rather difficult and loaded with mood swings, short temper, frustration, low energy, and bouts of ‘hanger.’ This is really why it’s important to prepare properly for your fast.
You will typically get hungry around your typical meal times today, mostly out of habit. If you have very set meal times, it may be useful to ensure you are busy or distracted during these times, so that the hunger wave can come and pass with ease.
Sleep on day 1 is typically better than normal since your body is not dividing its energy between digesting and the other functions that happen while you sleep.
Day two of the five-day water fast can bring about bouts of ‘hanger’, no matter how much preparation you have done. This is a result of your blood glucose levels dropping and your ketone levels rising. This is the hallmark of a fast: the shift into fat-adaptation, whereby the body is burning fat (ketones) for fuel instead of sugar (glucose).
Since your body is used to using glucose for sugar, and the brain is especially reliant on these sugars for rapid fuel, this second day can bear some brain fog and mild mood swings or energy dips. It is not necessarily going to be all that intense, especially if you’re generally healthy and have prepared for the fast. But out of all the days, day 2 is generally the hardest day as your body transitions into ketosis.
By the end of day 2, if you can get by, you’ll make it all 5. Emotionally this is the most common day that people quit, so use all your willpower to get to bed at the end of day 2 and trust that you will wake up on the other side of it.
The sleep of night 2 will probably be the most disturbed out of all 5 days since the body is under the stress of low-glucose without having fully transitioned into ketosis. This stress can cause the release of the stress hormone cortisol, that releases glucose into the bloodstream (a fight-or-flight response. Cortisol dump in the middle of the night can wake you up, although you should still fall asleep.
Many people, however, still report a deep sleep anyway. If you can avoid work or commitments for the first few days, leaving a buffer zone in case you do get poor sleep and need more rest during the day time.
This is the transition day for most people, where you move from being a sugar burner to being fully fat adapted. For those who aren’t used to burning fat for fuel (if you normally have a low-fat diet or no experience with intermittent fasting) today may come with some hunger waves or slight brain fog, but most people should be feeling pretty good today.
Once your brain does adapt to burning ketones, you should be thinking more clearly than ever because ketones burn to incredibly clean. This clarity is one of the largest benefits of the fast; there is very little waste of this fuel source. Ketones are like burning a gas stovetop, whereas glucose is like burning firewood. Both heat up the stove, but fire creates a lot of smoke and waste, which shows up in the body as inflammation if the pathways aren’t working perfectly well (which often they are not).
These deep benefits of high ketone levels, which include clarity but also immune-boosting, gut healing, and more, require a high dose of ketones that simply isn’t available on a ‘keto diet’. Fasting provides the body with a therapeutic dose of ketones, which is why prolonged water fasts are so healing. Ketones by day 3 should be between 3 and 4 mmol/L, with levels raising up to 6, 7, and even 8 mmol/L towards the end of day 5. A keto diet with intermittent fasting hovers around 1 mmol/L.
By the end of day 3, your body may start to get cold. This is absolutely normal, as your body’s entire energy store is being focused on healing the body instead of the metabolic fire of digestion. Stay warm with extra layers, hot water bottles, sit by the fire or crank up the heat.
Day four is the day where most people experience major autophagy. Autophagy is the process whereby your body eats out ‘bad’ cells (senescent cells) first, to use for energy and survival during a fasted state. These cells are inflammatory, sluggish, and essentially old or damaged, which are then replaced by a surge of fresh stem cells once you re-feed post-fast.
The way to test for deep autophagy is with a blood glucose test and look for a ratio of 1:1 with glucose and ketones. So with a glucose reading of 65, you would divide it by 18 to get the European standard, which is 3.6. A ketone measurement may be around 3.6 as well, which would highlight deep autophagy. The lower the glucose and the higher the ketone ratio, the better.
Today you should feel on top of the world, and around day 4 you should feel like you are capable and wanting to fast ‘forever’.
By day five, your stem cell rise is peaking, and you should be feeling great. Today when you break the fast it’s absolutely crucial to do so properly since the way you break your fast dramatically influences the results.
When breaking a fast, go slowly by eating very soft, easily digestible foods such as berries, soft avocados, and veggies that are steamed or blended. A little coconut oil or olive oil can be good as well, but consume just a little bit at a time.
Remember: it will take the body time to adjust to eating again. Patience is key.
Ease back into eating by consuming very basic foods instead of big, heavy meals. Your digestive enzymes will be sluggish after the fast. It’s also beneficial to wait a few days before adding meat back into your diet. Your digestive system has just rested for a very long time and needs time to adapt back to processing food again.
Take the opportunity post-fast to really re-examine your relationship with food and your diet. Since your tastebuds will be ‘reset’, this is the perfect time to remove highly palatable processed foods, loaded with refined sugar, fat, and salt, and opt for a more natural whole-food diet.