Tim Ferriss 3-Day Fasting Protocol

If you are at all familiar with Tim Ferriss, you know he is a huge fan of fasting. Tim aims for a 3-day fast once per month and a 5- to 7-day fast once per quarter. Every week it seems like there is a new study that comes out that reveals even more benefits to fasting. While fasting has enjoyed a recent surge in popularity, it has been practiced for thousands of years and has often played a key role in different religions and cultures.

In his New York Times best-selling book, Tools of Titans, Tim takes a deep dive into his own fasting protocol in the chapter on Dr. Dominic D’Agostino. Dr. D’Agostino has PhD in Neuroscience and Physiology from Rutgers University and is currently an associate professor at the University of South Florida Morsani College of Medicine, as well as being a senior research scientist at the Institute for Human and Machine Cognition. An expert in all things ketogenic diet and fasting, Dom is famous for deadlifting 500 pounds for 10 reps after a 7-day fast.

RELATED READING: Dr. Peter Attia’s Supplement List, Biohacking Toolkit, and Diet

Dr. D’Agostino is a huge proponent of a “purge fast”, saying: “If you don’t have cancer and you do a therapeutic fast 1 to 3 times per year, you could purge any precancerous cells that may be living in your body.” Studies also suggest that fasts of 3 days or longer can “reboot” your immune system, killing off healthy cells via stem cell-based regeneration.

Ferriss has been experimenting with fasting for years. His first foray into fasting was years ago in an effort to cure his debilitating Lyme disease. Ferriss did a 7-day fast that was medically supervised in a clinic where he lost 12 pounds and was in excruciating pain. In spite of that, Tim noticed a dramatic improvement in his Lyme disease, and began his journey to optimize fasting.

The longest fast Ferriss has completed to date was 10 days. Miraculously, Tim lost ZERO muscle mass on this particular fast while have a much easier experience compared to his first one. So what made the difference on this particular fast?

  1. Consume trace amounts of BCAAs and around 300 to 500 calories of pure fat per day during the fast. Specifically, Ferriss recommends consuming roughly 1.5 g of BCAAs upon waking and 3 g of BCAAs during his workout. Tim doesn’t mention the specific brand of BCAAs he takes, but Dr. D’Agostino recommends Scivation Xtend BCAAs (I also use this brand). The 300 to 500 calories of fat will be consumed via MCT oil or coconut oil.
  2. Tim got into ketosis as fast as possible to prevent muscle wasting. According to Tim, he can get into ketosis in under 24 hours instead of 3 to 4 days. By following Tim’s 3-day fast protocol below, you should be able to achieve the same results.

RELATED READING: Dr. Rhonda Patrick’s Supplement List

Tim Ferriss’ Fasting Protocol Overview

  • Consume exogenous ketones 3 times daily at 3- to 4-hour intervals. Tim primarily uses KetoCaNa and a C8 (caprylic acid) supplement such as Brain Octane. An exogenous ketone supplement helps to prevent carb withdrawal and get into ketosis quicker.
  • Up to 4 tablespoons of fat (e.g., coconut oil in coffee) is also allowed, just make sure to consume 300-500 calories from fat. Ferriss rewards himself with an iced coffee with a bit of coconut cream during the afternoons of his fast. He will also occasionally reward himself with a SeaSnax packet of nori sheets at the end of the day.
  • Walk 3 to 4 hours the first morning of the fast to get into ketosis faster.
  • Sleep as late as possible on Friday, Saturday, and Sunday mornings. The goal is to let sleep do some of the work for you.

3-Day Fasting Protocol By Day


  • Plan phone calls, podcasts or any other way you can be productive on your phone for four hours for Friday. This will make sense momentarily.
  • Eat a low-carb dinner around 6 p.m. This will be your last meal before the fast.


  • Immediately upon waking, consume exogenous ketones such as KetoCaNa or MCT oil. Do this 2 more times throughout the day, preferably at 3- to 4-hour intervals.
  • Consume some caffeine and be prepared to walk for 3 to 4 hours. Aim to be out the door within 30 minutes of waking. Grab a cold liter of water and add a few inches of salt and consume while walking. Be sure to keep consuming a large amount of water throughout the day. Use the walk to make scheduled phone calls or listen to an audiobook or podcast. Walking will burn up your glycogen stores, making you get into ketosis much faster.


  • After Friday’s walk, you should now be in ketosis. You can test your ketone level using a testing kit. Tim uses the Precision Xtra to test his blood ketones. You should be at around 0.7mmol or greater at this point. Another option to test your ketone level is to use urine ketone test trips, but they are messy and often inaccurate.
  • Continue to consume exogenous ketones 3 times daily at 3- to 4-hour intervals, trace amounts of BCAAs, and 300-500 grams of fat.

Sunday Night

  • Follow the same supplement protocol as the previous days.
  • Break your fast and enjoy it! You deserve it. For a 3-day fast, what you eat doesn’t really matter, but for longer fasts you will need to think re-feeding carefully. Ferriss has had everything from steaks to salads to greasy burritos to break his fast Sunday night.

How To Stay In Ketosis Post Fast

The key to staying in ketosis post fast is to follow the ketogenic diet by eating a boatload of fat. Shoot for 1.5 to 2.5 g of fat per kilogram of body weight, 1 to 1.5 g of protein per kilogram of body weight, and next-to-no carbs.

Remember, your fats will need to make up 70 to 85% of your calories; otherwise, you risk falling out of ketosis. Tim wrote in Tools of Titans, “A chicken breast by itself will kick you out of ketosis, but a chicken breast cut up into a green leafy salad with a lot of olive oil, feta cheese, and some Bulletproof Coffee (for example) can keep you in ketosis.”

Fasting Supplements and Tools

Tim’s 3-day fast protocol does not work without proper supplementation. Below is a summary of all the supplements and tools needed for the fast, including the specific brands that Tim recommends.

  • BCAAsScivation Xtend BCAAs, 1.5 g upon waking and 3 g during walk or workout.
  • Exogenous Ketones – KetoCaNa, consumed three times daily at 3- to 4-hour intervals to stave off carb withdrawal and induce ketosis
  • MCT Oil – Tim uses Brain Octane, which is made of purely C8. Dr. D’Agostino uses a powdered form of MCT Oil by Quest Nutrition. If you prefer a flavored emulsified MCT oil that is tasteless and can be mixed in your favorite drink, we highly recommend Onnit’s Emulsified MCT Oil (use code ‘brainflow’ at checkout for 10% off).
  • Caffeine – Caffeine can help stunt your appetite and make getting through the fast easier. Tim will often have tea or coffee with some Coconut oil. He also drinks Bulletproof Coffee.
  • Ketone Testing KitPrecision Xtra, to accurately test ketones levels the second day of the fast.


We hope you enjoyed our article on Tim Ferriss’ 3-day fasting protocol. The coolest part of Tim’s protocol is that it allows you to get into ketosis in under 24 hours! This can make transitioning to the ketogenic diet much easier, while reaping the benefits of fasting.

If you enjoyed this article, be sure to check out Tim Ferriss’ daily supplement stack as well as his morning routine. If you have any questions, feel free to comment below.

Scroll to Top