How (and Why) to Survive a 3 Day Water-Only Fast

Improving mental performance often includes adding things into your daily life and routine, such as the case with nootropics and smart enhancers. Biohackers are notorious for adding new technologies, lifestyle habits, and supplements to improve their mental performance.

At times, it is additive to remove things from our daily life to optimize our brain. One practice exemplifies this the most: fasting. Even though fasting has become more popular over recent years, most mainstream adherents follow a process called "intermittent fasting," which entails small windows of daily eating and 16 - 20 hours of fasting per day.

This methodology can have tremendous benefits for cognition including increased BDNF (fertilizer for the brain), which supports memory and learning ability. Animal research also suggests this calorie restriction can protect the brain from neurodegenerative problems.

But sometimes, fasting for longer stretches is even more effective. Below we'll explain what benefits come from multi-day fasts and how to survive them.

Longer is Better: Benefits of 3 Day Fasting

When it comes to fasting, longer is better... depending on your goals. It's not universally "better", but it can be a great tool. The immune health argument is one of the most well-studied by well respected USC researcher, Valter Longo.

In a 2014 study published in the journal Cell, Longo and his colleagues described major metabolic changes after extended 3 day fasts. After 3 days, subjects were producing more white blood cells (a marker of immune health).

According to Tim Ferriss, this is one of the reasons why he does 3-day fasts on a quarterly basis. Whereas daily calorie restriction can help to clear our cellular waste, going for 3 to 5 days will deplete the body's glycogen completely and require a far greater overhaul from the body.

2 Approaches to Extended Fasts

There are an infinite number of ways to see benefits from fasting, but with extended fasts, we are going to focus on only a couple.

1. Minimalist - this approach includes only water and salt for electrolytes
2. Modern - this approach incorporates caffeine and a few handy supplements

Both have advantages, but it depends on how far you are willing (or desire) to take the extended fasting protocol.

Minimalist Approach

The minimalist approach to fasting, as the name implies, is minimal. The idea is to mimic an ancestral environment as best as possible. Our ancestors did not have caffeine to blunt the hunger or branched chain amino acids (BCAA) to avoid muscle loss.

Even though some proponents of fasting believe caffeine will not "break" the fast, evidence from Dr. Rhonda Patrick suggests even a cup of coffee will halt certain mechanisms involved in the fasting process (skip to ~42:08 in the video).

Additionally, the BCAA (which we will mention later) create an insulin response, which will halt other mechanisms of fasting. For this approach, eat no food, drink nothing but water (with a pinch of salt added), and include no supplements (not even multi-vitamins).

Modern Approach

The modern approach takes advantage of some modern creature comforts while still activating many of the long-term fasting benefits. This includes coffee and tea, which are both minimal in their calories, but have a hunger suppressing effect.

People who experience strong hunger pains find this eases the process. Some people use supplements as well. The two that come to mind are BCAA, which can help to preserve muscle during extended fasts, and exogenous ketones, which will accelerate the process of using fat (ketones) for energy.

NOTE: Be careful with which exogenous ketones you use. Beta hydroxybutyrate (BHB) is the most common ketone and it is often packaged with MCT powder, which can be filled with calories and knock you out of fasting.

The 3 Day Fasting Timeline

Fasting for 72 hours can seem more daunting than it is. The most challenging aspect of a 3 day fast is actually breaking the fast at the end (more on that later). Our recommendation on this timeline comes from Tim Ferriss and his experience. Having 70% of the fast over the weekend may help you to avoid interruptions with your professional life.

• Thursday, 8PM - Finish your last meal and begin fasting
• Friday, 8AM - Begin walking for 3-4 hours. This is to help deplete glycogen stores and make the process of converting from glucose fuel to fat fuel. If you'd like to drink some coffee beforehand, that could work too. Try to schedule some calls or listen to audiobooks while walking.
• Friday / Saturday - Whenever you can go for extended walks, do so. It usually takes 24 - 48 hours to fully deplete glycogen (depending on your experience and diet). The more you walk the quicker the process.

IMPORTANT: Make sure you are drinking plenty of water, but not too much. Gauge your water consumption by thirst. If you over-drink, it could flush too many electrolytes out of your system. Add a pinch of salt to avoid this as well.

Unless you're borderline masochistic, going out with friends can be a challenge. This author decided to join two friends at a BBQ and watched them consume finger-licking brisket after 50 hours of fasting. If you cannot take the mental torture, don't put yourself in these positions! The hardest part about a 3 day fast isn't the hunger pains, it is breaking the fast. 

There are many methodologies for this process, but our friend Nat Eliason provided some useful feedback. Part of his approach is included. After the fast is over, the tendency is to desire face-stuffing, epic food portions, and all the food you can find. Don't do this. Not only will you feel terrible, but in your current physical state, it can kill you.

• 72 hours fasted - Turmeric tea. Simply steep some tea and add turmeric. The idea here is to prepare the digestive system for incoming calories and food-stuff without overwhelming it.
• 72 hours 30 minutes - Bone broth. There are a host of bone broth nutrition benefits, but the objective is to get some calories (in the form of fat) and prepare the digestive system further for food.
• 73 hours - Eat food (with fewer carbs). Now you can eat some solid foods. Nat ate almonds, I consumed some pickles and sauerkraut, but don't go full-blown pasta carbonara just yet.
• 73 hours 30 minutes - Eat with fewer restrictions. We suggest avoiding too many high-glycemic foods, but by this point your system should be adapting to the foodstuff. Just make sure you stay near a bathroom if you are unsure (yikes!)

Voila! After fasting for 3 days most people feel great, have a newfound respect for fasting, and an appreciation for simple foods. Beyond the long-term benefits for anti-aging, longevity, and immune health, this process usually provides a psychological boost as well. People who willingly create a challenge for themselves and accomplish something meaningful often find the highest value.

Is Fasting Right for Everyone?

While you now have a better understanding of why extended fasts are useful and tips on surviving, that doesn't mean the process is for everyone. Fasting deprives the body of all energy resources, which can be a health concern for many people. While it is true that humans can last months without food, it's useful to only do so with the care of a physician. Elderly and those struggling with chronic issues can find benefits through extended fasts, but it is better to speak to a medical professional before doing so. This way you not only have someone watching out for you, but also a guideline for your limitations given existing medical conditions.

If you find that extended fasting is a practice you not only desire, but have the capability to do, then take advantage of all the luxuries afforded by removing something from your life. Happy fasting!