What do you think?
Rate this book
Fast This Way: How to Lose Weight, Get Smarter, and Live Your Longest, Healthiest Life with the Bulletproof Guide to Fasting
Break the rules, not the fast with world-renowned biohacker and New York Times bestselling author Dave Asprey.
For more than a decade, the Bulletproof founder Dave Asprey has shared his unique point of view and expertise to help fans become the best versions of themselves. From living longer to getting smarter, maximizing performance to practicing mindfulness, Dave’s followers look to him for his take on the most effective techniques to become healthier and more powerful than most doctors think is possible.
Asprey has been fasting for years, long before it gained widespread popularity, and if you’re a fan of Bulletproof coffee and The Bulletproof Diet, you have been enjoying some of the benefits of Intermittent Fasting too.
In Fast This Way, Dave asks readers to forget everything they think they know about the ancient practice and takes them on a journey through cutting-edge science to examine the ways novice fasters and Intermittent Fasting loyalists can up-end their relationship with food and upgrade their fasting game beyond calorie restriction.
What IF eating the right foods at the right time can actually enhance your fast?
What IF how you work out and sleep could trick your body into thinking you are fasting?
What IF it were easy to skip a meal, or two, or three?
What IF fasting is different for women, can be personalized to your genes, and can impact your mental health?
What IF all fasts could be created equal?
Fast This Way is a compelling read through the latest thinking on fasting and gives readers the manual and toolkit to make the most of their fasts and their personal biology.
For more than a decade, the Bulletproof founder Dave Asprey has shared his unique point of view and expertise to help fans become the best versions of themselves. From living longer to getting smarter, maximizing performance to practicing mindfulness, Dave’s followers look to him for his take on the most effective techniques to become healthier and more powerful than most doctors think is possible.
Asprey has been fasting for years, long before it gained widespread popularity, and if you’re a fan of Bulletproof coffee and The Bulletproof Diet, you have been enjoying some of the benefits of Intermittent Fasting too.
In Fast This Way, Dave asks readers to forget everything they think they know about the ancient practice and takes them on a journey through cutting-edge science to examine the ways novice fasters and Intermittent Fasting loyalists can up-end their relationship with food and upgrade their fasting game beyond calorie restriction.
What IF eating the right foods at the right time can actually enhance your fast?
What IF how you work out and sleep could trick your body into thinking you are fasting?
What IF it were easy to skip a meal, or two, or three?
What IF fasting is different for women, can be personalized to your genes, and can impact your mental health?
What IF all fasts could be created equal?
Fast This Way is a compelling read through the latest thinking on fasting and gives readers the manual and toolkit to make the most of their fasts and their personal biology.
Audiobook
First published January 1, 2021
1592 people are currently reading
1848 people want to read
About the author
Dave Asprey
62 books586 followersDave Asprey and his brands promote using science and biohacking technology to give you control of your body and mind, so you can upgrade to a happier more conscious state.
Known as "The Father of Biohacking, "Dave Asprey is an award-winning entrepreneur and innovator in the biotech and health science space. He’s the creator of Bulletproof Coffee and mineralized, mold-free Danger Coffee, the host of the Webby Award-winning #1 rated health podcast, The Human Upgrade (formerly Bulletproof Radio), and a multi-New York Times bestselling author of Game Changers, Head Strong, The Bulletproof Diet, and Smarter Not Harder.
Over the last two decades, Dave has worked with world-renowned doctors, researchers, and global mavericks to discover and put into practice the latest, most innovative methods, techniques, and products for enhancing mental and physical performance. Dave has personally spent millions taking control of his own biology – pushing the bounds of what’s humanly possible all in the name of scientific evolution and revolution. As the creator of The Bulletproof Diet and Bulletproof Coffee, collagen protein supplements, and many more commercial wellness products, Dave’s mission is to empower people not only with information and knowledge, but also the tools and techniques that unlock individual potential for the greater global good. To bring his knowledge to the public, Dave created the Biohacking Conference, the largest, longest-running Biohacking Conference in the world, celebrating its 11th anniversary in 2025.
Known as "The Father of Biohacking, "Dave Asprey is an award-winning entrepreneur and innovator in the biotech and health science space. He’s the creator of Bulletproof Coffee and mineralized, mold-free Danger Coffee, the host of the Webby Award-winning #1 rated health podcast, The Human Upgrade (formerly Bulletproof Radio), and a multi-New York Times bestselling author of Game Changers, Head Strong, The Bulletproof Diet, and Smarter Not Harder.
Over the last two decades, Dave has worked with world-renowned doctors, researchers, and global mavericks to discover and put into practice the latest, most innovative methods, techniques, and products for enhancing mental and physical performance. Dave has personally spent millions taking control of his own biology – pushing the bounds of what’s humanly possible all in the name of scientific evolution and revolution. As the creator of The Bulletproof Diet and Bulletproof Coffee, collagen protein supplements, and many more commercial wellness products, Dave’s mission is to empower people not only with information and knowledge, but also the tools and techniques that unlock individual potential for the greater global good. To bring his knowledge to the public, Dave created the Biohacking Conference, the largest, longest-running Biohacking Conference in the world, celebrating its 11th anniversary in 2025.
Ratings & Reviews
Friends & Following
Create a free account to discover what your friends think of this book!
Community Reviews
Displaying 1 - 30 of 238 reviews
November 13, 2020
I’m on the fence about this book. There were some things in it that were insightful and that I want to try. I enjoyed hearing about his spiritual fast in a cave, which frames the entire book. Though, it was a little out there for me at times. As a fasting purist, I didn’t like that he repeatedly says that fasting purists are miserable and struggle to make it through each fast. That isn’t the case in my life, and it isn’t the case in many purist IFers’ lives. I think the section where he talks about women and fasting is full of broad generalizations that lack consistent scientific studies to back them. And, while saying he isn’t trying to sell Bulletproof coffee, he does promote it throughout the book. However, I don’t think I am his target audience. This books seems to be more for people who have never tried fasting and know nothing about it. Overall, it is a book that would be a good introduction to fasting for somebody who has never tried it and is curious about fasting.
January 19, 2021
A big long chat about Dave’s pilgrimage, Fasting and how it might effect or apply to you;
This is NOT your typical health book. The science is spare and Dave’s experiences are everywhere: multiple caves, shamans, deserts, mountains...That’s not to say there’s no science, it’s just not front and center; Dave is - Bulletproof Coffee is.
Fasting is the subject of this book and there’s not much new here. I’ve been successfully practicing IF for a year and thankfully started with Jason Fung & Gin Stephens; more scientific and how-to than what you’ll find here. “Fast This Way” is a largely anecdotal volume that chronicles Dave Asprey’s history with fasting. He does get around to giving some suggestions for pairing exercise with fasting and what time and what types of exercise make the best impact. Be prepared to take notes or use an highlight function. There’s little recapping or summary in his writing. It’s like listening to a chilled out professor ramble on - this guy actually refers to the sex act as bonking🥴
Anyway, the highlights of this volume for me were: Chapter 3’s - Stages of Fasting - where there’s a clear explaining of how the body responds at various timed intervals (most people) Chapter 8 - has some interesting info on vitamins, supplements and the possible impact on/with fasting. IMO, this needs further investigation on my part, but it’s a good jumping off place. Chapter 9 - is a good discussion about how fasting is different for women based on hormonal seasons of life.
The remainder of the book is largely Dave’s experiences and philosophical approaches rather than science or it’s information readily available to anyone asking their “assistant” to the masses to grant them an info dump on the subject. Particularly weak are the chapters on sleep and mental & spiritual health.
On a technical issue, the Notes section of the book is interactive and will take you back to that section of text in the Kindle Edition. It does NOT work in both directions and the Index is NOT interactive - it’s setup to match the HC version.
Easy to read and accessible, perhaps this book will be best suited for those who are followers of Dave, the Bulletproof Plan or those who are very new to Fasting. Seasoned IF’ers will not find any new revelations or challenges for their journey 📚
This is NOT your typical health book. The science is spare and Dave’s experiences are everywhere: multiple caves, shamans, deserts, mountains...That’s not to say there’s no science, it’s just not front and center; Dave is - Bulletproof Coffee is.
Fasting is the subject of this book and there’s not much new here. I’ve been successfully practicing IF for a year and thankfully started with Jason Fung & Gin Stephens; more scientific and how-to than what you’ll find here. “Fast This Way” is a largely anecdotal volume that chronicles Dave Asprey’s history with fasting. He does get around to giving some suggestions for pairing exercise with fasting and what time and what types of exercise make the best impact. Be prepared to take notes or use an highlight function. There’s little recapping or summary in his writing. It’s like listening to a chilled out professor ramble on - this guy actually refers to the sex act as bonking🥴
Anyway, the highlights of this volume for me were: Chapter 3’s - Stages of Fasting - where there’s a clear explaining of how the body responds at various timed intervals (most people) Chapter 8 - has some interesting info on vitamins, supplements and the possible impact on/with fasting. IMO, this needs further investigation on my part, but it’s a good jumping off place. Chapter 9 - is a good discussion about how fasting is different for women based on hormonal seasons of life.
The remainder of the book is largely Dave’s experiences and philosophical approaches rather than science or it’s information readily available to anyone asking their “assistant” to the masses to grant them an info dump on the subject. Particularly weak are the chapters on sleep and mental & spiritual health.
On a technical issue, the Notes section of the book is interactive and will take you back to that section of text in the Kindle Edition. It does NOT work in both directions and the Index is NOT interactive - it’s setup to match the HC version.
Easy to read and accessible, perhaps this book will be best suited for those who are followers of Dave, the Bulletproof Plan or those who are very new to Fasting. Seasoned IF’ers will not find any new revelations or challenges for their journey 📚
May 19, 2021
I am someone who practices intermittent fasting and I did some extensive research on that before, so most of things said in this book were already familiar to me. But it was great to know in even more depth about intermittent fasting (IF). The author tells about his journey with IF and how it helped him. He tells us in details about the benefits of IF and how good it is for our health. And it's true. I myself feel very good when I fast. I can relate to the author when he talks about how IF changed him forever. I think IF will stick with me for the rest of my life.
One thing that was an issue for me was that the author was kind of repetitive. He repeats few things again and again. This was a tiny issue I had with this book. Other than that it was a great nonfiction book was fasting. I'd highly recommend this book!
One thing that was an issue for me was that the author was kind of repetitive. He repeats few things again and again. This was a tiny issue I had with this book. Other than that it was a great nonfiction book was fasting. I'd highly recommend this book!
March 21, 2021
While this book has a lot of information, (some of it questionable), it also has a lot of... personality. If you’re interested in Dave Asprey, his life experiences and opinions, you’ll enjoy this book. If, like me, you would have appreciated a book half this size with succinct, relevant information only, and without the endless mentions of his bullet-proof coffee formula, this book will irritate you. I much preferred Jason Fung’s Complete Guide to Fasting over Asprey’s self promotional fasting autobiography.
January 25, 2021
Interesting take on fasting, that opened my eyes to some new concepts. A lot of overlap from his bulletproof diet book though, so if you've read that, be prepared for some strong review. One of the first things I've read that addresses the differences for men and women as well as really detailed strategies for being successful with fasting. Worth a read if you are interested in fasting, or just having a deeper understanding of how your eating patterns affect your health and wellness.
February 24, 2021
Don’t waste your money. There are far better books on fasting out there. Dave’s personal story of hue vision quest fast was interesting but would have made a better blog post or magazine article rather than filler in a book.
April 7, 2021
I have always despised the theory where it is advisable to keep eating something at regular intervals. I never got benefitted from it neither spiritually nor mentally or physically. Infact it made me less focussed and more prone to weight gain. I am the kind of person who takes maximum 2 meals a day or sometimes even one and enjoy it to the fullest. Quite recently, I come to know that this concept of keeping long duration between two successive meals is known as intermittent fasting and finds its mention almost everywhere plus it is quite useful for our health too as per many research results.
Fasting is something which is quite important for our overall well being and its roots can be traced dated way back to the ancient times. It isn't a new concept and followers of Sanatan Dharma have always been propagating the ideas of it. Though off lately even the western people have also started getting the vitality of it and have been deeply involved in spreading the message that how one can change his or her life entirely just by keeping fast or atleast skipping meals after regular course to purify the body and ultimately our soul.
This book is a really good attempt in bringing into light about everything related to fasting and how it can help one immensely and hence should be incorporated by every being into their routine lifestyle. It offers great insights for anyone who is a beginner though people who are fasting purist since long won't get much new values from it. It also conveys how the practice differs for both men and women and depends on how one's body mechanism copes with it. Also depending on whether one is adopting it for religious reasons or fat loss, the way and thereby the results differ precariously.
All in all, an interesting well researched book on an invaluable topic
Fasting is something which is quite important for our overall well being and its roots can be traced dated way back to the ancient times. It isn't a new concept and followers of Sanatan Dharma have always been propagating the ideas of it. Though off lately even the western people have also started getting the vitality of it and have been deeply involved in spreading the message that how one can change his or her life entirely just by keeping fast or atleast skipping meals after regular course to purify the body and ultimately our soul.
This book is a really good attempt in bringing into light about everything related to fasting and how it can help one immensely and hence should be incorporated by every being into their routine lifestyle. It offers great insights for anyone who is a beginner though people who are fasting purist since long won't get much new values from it. It also conveys how the practice differs for both men and women and depends on how one's body mechanism copes with it. Also depending on whether one is adopting it for religious reasons or fat loss, the way and thereby the results differ precariously.
All in all, an interesting well researched book on an invaluable topic
February 5, 2021
I have purchased an abundance of books on diet and nutrition. Many of them very good - but I have never read one cover to cover before now. It is a subject I find fascinating, but I tend to read pieces of each book, I don’t read them cover to cover. But this one, I did.
I have always been intrigued by fasting - especially from a spiritual perspective - but have never tried it because it sounded like something I personally could not do. But as I heard more and more about the health benefits of intermittent fasting, I experimented with it. I didn’t love it. But I could see some benefits.
When I heard the author, Dave Asprey, talk about his new book “Fast the Way” I was blown away at the stacks of health benefits he was rattling off. So I bough the book. I read it cover to cover. And - most importantly- I started using the strategies for building fasting stamina and I love it!
This book is easy and engaging to read, and it gives you a roadmap for planning how you personally will approach incorporating fasting into your overall health routine. And my favorite part - it delves into the synergy between fasting for spiritual reasons and fasting for health reasons.
I have always been intrigued by fasting - especially from a spiritual perspective - but have never tried it because it sounded like something I personally could not do. But as I heard more and more about the health benefits of intermittent fasting, I experimented with it. I didn’t love it. But I could see some benefits.
When I heard the author, Dave Asprey, talk about his new book “Fast the Way” I was blown away at the stacks of health benefits he was rattling off. So I bough the book. I read it cover to cover. And - most importantly- I started using the strategies for building fasting stamina and I love it!
This book is easy and engaging to read, and it gives you a roadmap for planning how you personally will approach incorporating fasting into your overall health routine. And my favorite part - it delves into the synergy between fasting for spiritual reasons and fasting for health reasons.
March 6, 2021
Dave clearly has his preferred method which is the “Bullet Proof Method” and is very derogatory to “fasting purists”. Dave is a bio hacker and is more interested in the short cuts, this books is at times interesting but there are very few deep dives here. I think Jason Fung’s work is a better start for most people since he explains several of the mechanisms for why fasting helps people - and yes, a complete abstinence from food, and food flavors, is what you need to keep your body from releasing insulin for a few hours. A process which has been proven to help people heal from all sorts of insulin related problems.
January 31, 2021
I just finished an 8 day water fast. I liked Dave's approach to make fasting something that should be enjoyable using specific hacks. I included bulletproof coffee in my fast and that served me well. I felt great after finishing the fast and many of my aches and pains in my joints felt better from the body healing the inflammation. I am planning on making fasting more a part of my stack because of how it made me feel. Dave's book does a great job of making you understand not only how to do it but that you shouldn't be fearful of it. Happy Fasting!
May 22, 2021
First off, Dave Asprey is not an "expert" on this subject...he's an opinionated practitioner. If you want to read real science, follow someone like Jason Fung who has spent his whole adult life studying the subject. This book was very hard to get through, as it's just a very long and opinionated (and perhaps a little narcissistic) promotion of Dave's Bulletproof Coffee version of fasting. Nothing to learn here that you can’t learn from experts in much more detail. Would not recommend at all. In fact, after reading this book I have pretty much blocked all things Dave Asprey.
May 18, 2021
I read this after it was recommended by pro wrestler Daniel Bryan. I forgive Daniel. At about a hundred pages in a natural question came to me: How many times is this guy gonna plug his effin coffee?! Mine was the hardcover copy from the library so I went to the fasting subreddit and asked if anyone with a Kindle copy would mind doing a quick search for how many times the name of the coffee shows up. My guess was eighty. The answer was 110. Yup, in a 250-page book he manages to plug his coffee almost every other page. Keep in mind that's an average, sometimes he plugs it twice in the same sentence. But that's not all, he has plenty of other things to promote. Supplements, his podcast, his previous books... there is room for all of them in here.
Having said that, Asprey does cover the basics in an easy-to-digest style (I realize the irony of that expression here). So take the stuff that sounds like podcast filler with a grain of salt (ditto).
Having said that, Asprey does cover the basics in an easy-to-digest style (I realize the irony of that expression here). So take the stuff that sounds like podcast filler with a grain of salt (ditto).
June 29, 2021
Bulletproof coffee anyone!?
April 24, 2021
Last Sunday, when I finally got a bit of me time, I went looking for a fast paced engaging read, but something different from the usual genres I read. I ended up picking up Dave Asprey's Fast This Way.
I turned the book over, to scan the blurb, it ticked all the check boxes.
•What IF eating the right foods at the right time can actually enhance your fast?
•What IF how you work out and sleep could trick your body into thinking you are fasting?
•What IF it were easy to skip a meal, or two, or three?
•What IF fasting is different for women, can be personalised to your genes, and can impact your mental health?
•What IF all fasts could be created equal?
Dave Asprey, the world renowned bio-hacker and New York Times bestselling author, brings to us a completely practical guide to practicing mindfulness, maximizing performance, excelling in life and becoming a better version of ourselves. When we scrutinise the topic of fasting, usually the first thing that comes to mind is food and weight-loss, fasting has more to it that this. Not smoking is nicotine fasting, so on and so forth. It revolves primarily around the principle: fasting is going without, bit going without doesn't always mean going without everything.
Fast This Way is a compelling and engaging read, and the practicality it presents to it's readers; the manual and toolkit to make the most of their fasts and their personal biology.
I turned the book over, to scan the blurb, it ticked all the check boxes.
•What IF eating the right foods at the right time can actually enhance your fast?
•What IF how you work out and sleep could trick your body into thinking you are fasting?
•What IF it were easy to skip a meal, or two, or three?
•What IF fasting is different for women, can be personalised to your genes, and can impact your mental health?
•What IF all fasts could be created equal?
Dave Asprey, the world renowned bio-hacker and New York Times bestselling author, brings to us a completely practical guide to practicing mindfulness, maximizing performance, excelling in life and becoming a better version of ourselves. When we scrutinise the topic of fasting, usually the first thing that comes to mind is food and weight-loss, fasting has more to it that this. Not smoking is nicotine fasting, so on and so forth. It revolves primarily around the principle: fasting is going without, bit going without doesn't always mean going without everything.
Fast This Way is a compelling and engaging read, and the practicality it presents to it's readers; the manual and toolkit to make the most of their fasts and their personal biology.
January 23, 2021
Loved the all aspect of life take on fasting
I’ve read all of Dave’s books other than the baby one, since that wasn’t a topic of interest for me. I have learned things in all of them that have radically improved my life. Much of it was science and technical information.
I enjoy his podcast and am a customer of Bulletproof, True Dark, and a Biohacker box subscriber. If finances allow, I’d love to experience 40 Years of Zen someday.
I have read many books on fasting since my doctor first recommended it 4 years ago. I felt confident I understood the biological benefits of fasting, and practiced intermittent fasting along with some multiple day fasts over the years.
Still, Dave has blown my mind with Fast This Way! This book is so much more than an informative resource on fasting biology. It is an easy to read, engaging conversation between Dave and the reader. He uses a very profound personal experience to explain the spiritual, emotional, human aspects of fasting.
I had so many aha moments while reading this book. It has sparked a life change in me. I look forward to utilizing fasting from many things other than food in order to enrich my life. In particular I plan to start with fasting from self judgment. I think that will sweeten any other things I choose to go without.
I’ve read all of Dave’s books other than the baby one, since that wasn’t a topic of interest for me. I have learned things in all of them that have radically improved my life. Much of it was science and technical information.
I enjoy his podcast and am a customer of Bulletproof, True Dark, and a Biohacker box subscriber. If finances allow, I’d love to experience 40 Years of Zen someday.
I have read many books on fasting since my doctor first recommended it 4 years ago. I felt confident I understood the biological benefits of fasting, and practiced intermittent fasting along with some multiple day fasts over the years.
Still, Dave has blown my mind with Fast This Way! This book is so much more than an informative resource on fasting biology. It is an easy to read, engaging conversation between Dave and the reader. He uses a very profound personal experience to explain the spiritual, emotional, human aspects of fasting.
I had so many aha moments while reading this book. It has sparked a life change in me. I look forward to utilizing fasting from many things other than food in order to enrich my life. In particular I plan to start with fasting from self judgment. I think that will sweeten any other things I choose to go without.
February 1, 2021
There are better books on fasting (Jason Fung's for example) but this is an easy read if you want to start to explore fasting and assuming you like Dave Asprey's style; I do. I prefer his other books that go far deeper into a topic and share more cutting edge research.
July 17, 2021
I followed Dave,
not his way to Cave;
Vision quest,
a metaphor for the best;
But I'm dubious about consumption of supplements up to gram scale.
If activated charcoal avail, I'll pass MK-4 cocktail.
And why does he hate Kale?
not his way to Cave;
Vision quest,
a metaphor for the best;
But I'm dubious about consumption of supplements up to gram scale.
If activated charcoal avail, I'll pass MK-4 cocktail.
And why does he hate Kale?
January 31, 2021
I listened to this fantastic book in 2 days and am doing the 14-day fast challenge, priceless.
February 27, 2021
4 Stars
A comprehensive look at the mechanics and benefits of fasting. Lots of information for beginner and experienced fasters. Asprey shares hacks to make fasting easier, more effective, and even enjoyable.
I enjoyed his perspective on the spiritual aspects of fasting and the chapter devoted to the particular challenges women face when fasting. Throughout the book Asprey encourages the reader to listen to their bodies and fine tune fasting plans to fit their unique needs rather than adhering to rigid rules.
One drawback. There was tons of information and the book would have benefited from end of chapter summaries.
A comprehensive look at the mechanics and benefits of fasting. Lots of information for beginner and experienced fasters. Asprey shares hacks to make fasting easier, more effective, and even enjoyable.
I enjoyed his perspective on the spiritual aspects of fasting and the chapter devoted to the particular challenges women face when fasting. Throughout the book Asprey encourages the reader to listen to their bodies and fine tune fasting plans to fit their unique needs rather than adhering to rigid rules.
One drawback. There was tons of information and the book would have benefited from end of chapter summaries.
March 23, 2021
There’s always something to learn, even if one isn’t in full agreement with the author, which is the case in this book. Asprey has a different style of fasting than I do, and that’s okay. It doesn’t mean one of us is wrong and the other right. I’m not a coffee drinker, so his whole Bulletproof empire is totally lost on me. The chapters on sleep and supplementation were the most interesting to me. See? Always something to learn!
February 27, 2021
Very inspirational. Not only fasting from food, but also from tech, bad self-talk and other sings that don’t serve you. Good facts about women and fasting too. Will try the Bulletproof coffee (maybe tea since I don’t like coffee) with MCT oil on my fasting days. Will also add collagen again on nonfasting days.
August 23, 2021
2.5
I find it really hard to trust a book that spends half the time shamelessly self-promoting its products. I also found that it was lacking scientific studies to back its claims, it was more out of Dave’s own experience. Other than that I guess it was a decent read, it covers the basics and it was easy to digest, although there are far better books on fasting out there.
I find it really hard to trust a book that spends half the time shamelessly self-promoting its products. I also found that it was lacking scientific studies to back its claims, it was more out of Dave’s own experience. Other than that I guess it was a decent read, it covers the basics and it was easy to digest, although there are far better books on fasting out there.
February 8, 2021
Hum... Biohack your age... Very interesting
August 3, 2021
"Hunger is a biological message, and it is something that you can control. Craving is a psychological need, and it is something that tries to control you." [p8]
"Fasting is a habit changer. You will go without something and realize you didn't actually need it" [p32]
Hacks to help with ketosis
C8 MCT oil (caprylic acid) - converts almost directly in the liver via ketogenesis. As well as caproic acid (C6) and capric acid (C10); butyric acid (C4) should be even more rapid to convert to propanone (acetone), 3-hydroxybutyric acid (beta-hydroxybutyrate), and acetoacetate but can be difficult to digest. C12 (lauric acid) less so.
Activated carbon to fast - binds to lipopolysaccharide toxins that get created by gut bacteria and cause feeling of sickness. Also helps with detox. Studies have shown that activated carbon extends lifespan by absorbing toxins produced by gut bacteria, reduces cholesterol, promotes kidney function… But can make constipated
Supplements to maintain electrolytes: Ca, Mg, K, Na
Soluble fiber - attracts water in stomach and intestines, slows the digestive process - acacia gum, guar gum, larch arabinogalactan. Help to maintain healthy gut bacteria levels during a fast.
After fasting for several days/weeks, 1st meal should include protein, fat, vegetables, and lots of fiber.
Dose of carbs at dinner can help reduce anxiety due to serotonin release. Ok to eat a small amount of carbs if accompanied by MCT. Raw honey once or twice per week will take out of ketosis for a short period of time - raises glycogen in the liver, which preferentially feeds the brain.
Proteolytic enzymes (serrapeptase, nattokinase) produced in the pancreas break down proteins, but meant to support autophagy not digestion. Can supplement with these to aid digestion and break up clotting factors (Wobenzym and Masszymes are brands). Take 1-2 120,000 SU serrapeptase capsules and 1-2 2,000 FU nattokinase capsules daily.
Adaptogens
- Ashwagandha and rhodiola are stress-modulating
- Holy basil, ginseng, cordyceps are anti-inflammatory
- Reishi is relaxing
- Lion's mane aids nerve regeneration, Australian best
- Some can be extractged by water, others alcohol - go for liquid extracts over powder
Vitamins and Minerals
- Vitamin C, water soluble, take on an empty stomach for absorption (body can take up to 30g per day… best to limit to 1-4 g per day)
- B12 and folate, both water soluble. B12 protects against dementia, immune function, nerve support, increases immune function. Taking it creates a deficiency in folate - must be taken together. Causes neurological conditions if insufficient.
- A is fat soluble. Body is not efficient at converting beta-carotene into vitamin A, so difficult to get from food. Liver and oysters are the best source. 10,000 IU per day as a supplement improves immunity and can help with sleep.
- D is fat soluble, fights aging process, moderates immune function, facilitates hormonal response, calcium metabolism and bone formation. 1,000 IU of D3per 25lb body weight (or spend time in sun)
- E protects from cellular destruction - reco is natural over synthetic, even though natural is less stable?
- K2 is critical for calcium metabolism, works together with vitamin D. 1500mg per day
- I - critical for thyroid function. Iodized salt is chemically bleached. 150mcg per day, take in morning
- Mg - can cause loose stool, take with food. Body is naturally highest at noon, so take half in morning and half at bedtime. 800 mg per day
- K and Na - get from baking soda and salt. 200mg at bed
- Cr and V - modulate insulin levels. 200mg Chromium polynicotinate and 2mg vanadyl sulfate per day
- Zn and Cu - create CuZnSOD copper-zinc superoxide dismutase together, one of body's most potent natural defense mechanisms against molecular damage. 15mg zinc orotate and 2mg copper orotate with food
Amino Acids, fats, anti-inflammatories
- L-tyrosine boosts mood and cognition, able to cross blood-brain barrier. 750-1500mg in the morning before eating any other protein
- L-glutamine - Glutamine and BCAA's take body out of ketosis by raising insulin, but turns brain on. Take on an empty stomach… with MCT if you want to stay in ketosis
- Fish oil / krill oil - anti-inflammatory, improves brain function - needs to be high quailty unoxidized.
- Ginger (gingerols, shogaols, and paradols) and turmeric (curcumin)
- Antimicrobials and probiotics - grapefruit seed extract, do not take on an empty stomach
- Arginine, ashwagandha, boron, cnidium, folate, ginko biloba, ginseng, kava, maca (not raw, gelatinized), Mg, Se, Turmeric, Vitamin C, D3, Zn - for sex life
Sleep
Nighttime cortisol production kicks in around 3am - glymphatic circulation, critical part of sleep cycle to wash brain free of toxins. Cortisol release at 3am cleans individual neurons, but can make your mind race at 3am - try eating raw honey before bed (can take with MCT).
First light of sun in the morning - angle/color/intensity of light - believed to control 70% of circadian rhythms. Diet is 20% and Room temperature is the last 10%
Inflammatory foods that cause cravings and make fasting harder (mostly plant)
- High oxalate foods - induce body to produce calcium crystals. Oxalic acid C2O4(2-) waste product that can lead to kidney stones (attracts Ca2+?): sesame, soy, raw kale, spinach, chard, beets
- High histamine foods - released by WBC's in immuno-response: fish sauce, soy sauce, leftover fish, leftover pork
- Phytic acid - inhibits protein digestion: beans, grains, wheat, legumes
- Burned or charred meat, grains, vegetables - high temp cooking creates toxic compounds including (AGE, HCA, PAH)
- High lectin foods: tomatoes, potatoes, bell peppers, hot peppers, eggplant, beans, chickpeas
24hr fast triggers lipolysis (breakdown fats into constituent fatty acids). Fatty acids, converted into ketones through beta-oxidation. Liver releases ketones into bloodstream.
- After 24hrs ketones when glycogen depleted, ketones are primary fuel source
- Ketones help suppress ghrelin levels to manage hunger feelings
- In fasting, liver reduces secretion of IGF-1
Inflammation
- White rice always eaten by cultures over brown rice despite lower GI and higher nutrition of brown rice. Brown rice contains lectins and high contents of arsenic. Higher cravings due to difficulty to digest
- Neurons run best on ketones, glia run best on glucose - because of anti-inflammatory effects of ketones, produces calming sensation in glia.
- Gluconeogenesis is not only inefficient, but also produces many waste products (NH3)
- Hormesis - body thrives by adapting to adversity. Cold therapy proven for pain relief, faster recovery from injury, better mood, boosted immune system, weight loss, reduced risk of cancer and dementia. Strengthens lymphatic system and circulation
Types of Fasts
- 16:8 - standard 16hr fast / 8hr eating window
- Bulletproof (modification of 16:8) - MCT/coffee in morning, skip lunch or late lunch, finish eating by 8pm
- 5:2 fast - fast 5 days per week, eat 500-600 calories the other 2 days
- OMAD (23:1)
- Beware of the fasting trap: Fasting too frequently puts strain on body over time - creating an obsessive habit is never a good idea. Fasting too much will reduce sex hormones, thyroid hormone, increase cortisol and adrenaline, reduce muscle mass
- If you have a bacterial infection - avoid carbs and continue moderate fasting
- If you have a viral infection - eat protein and eat a moderate amount of carbs (not sugar), and MCT oil
"Fasting is a habit changer. You will go without something and realize you didn't actually need it" [p32]
Hacks to help with ketosis
C8 MCT oil (caprylic acid) - converts almost directly in the liver via ketogenesis. As well as caproic acid (C6) and capric acid (C10); butyric acid (C4) should be even more rapid to convert to propanone (acetone), 3-hydroxybutyric acid (beta-hydroxybutyrate), and acetoacetate but can be difficult to digest. C12 (lauric acid) less so.
Activated carbon to fast - binds to lipopolysaccharide toxins that get created by gut bacteria and cause feeling of sickness. Also helps with detox. Studies have shown that activated carbon extends lifespan by absorbing toxins produced by gut bacteria, reduces cholesterol, promotes kidney function… But can make constipated
Supplements to maintain electrolytes: Ca, Mg, K, Na
Soluble fiber - attracts water in stomach and intestines, slows the digestive process - acacia gum, guar gum, larch arabinogalactan. Help to maintain healthy gut bacteria levels during a fast.
After fasting for several days/weeks, 1st meal should include protein, fat, vegetables, and lots of fiber.
Dose of carbs at dinner can help reduce anxiety due to serotonin release. Ok to eat a small amount of carbs if accompanied by MCT. Raw honey once or twice per week will take out of ketosis for a short period of time - raises glycogen in the liver, which preferentially feeds the brain.
Proteolytic enzymes (serrapeptase, nattokinase) produced in the pancreas break down proteins, but meant to support autophagy not digestion. Can supplement with these to aid digestion and break up clotting factors (Wobenzym and Masszymes are brands). Take 1-2 120,000 SU serrapeptase capsules and 1-2 2,000 FU nattokinase capsules daily.
Adaptogens
- Ashwagandha and rhodiola are stress-modulating
- Holy basil, ginseng, cordyceps are anti-inflammatory
- Reishi is relaxing
- Lion's mane aids nerve regeneration, Australian best
- Some can be extractged by water, others alcohol - go for liquid extracts over powder
Vitamins and Minerals
- Vitamin C, water soluble, take on an empty stomach for absorption (body can take up to 30g per day… best to limit to 1-4 g per day)
- B12 and folate, both water soluble. B12 protects against dementia, immune function, nerve support, increases immune function. Taking it creates a deficiency in folate - must be taken together. Causes neurological conditions if insufficient.
- A is fat soluble. Body is not efficient at converting beta-carotene into vitamin A, so difficult to get from food. Liver and oysters are the best source. 10,000 IU per day as a supplement improves immunity and can help with sleep.
- D is fat soluble, fights aging process, moderates immune function, facilitates hormonal response, calcium metabolism and bone formation. 1,000 IU of D3per 25lb body weight (or spend time in sun)
- E protects from cellular destruction - reco is natural over synthetic, even though natural is less stable?
- K2 is critical for calcium metabolism, works together with vitamin D. 1500mg per day
- I - critical for thyroid function. Iodized salt is chemically bleached. 150mcg per day, take in morning
- Mg - can cause loose stool, take with food. Body is naturally highest at noon, so take half in morning and half at bedtime. 800 mg per day
- K and Na - get from baking soda and salt. 200mg at bed
- Cr and V - modulate insulin levels. 200mg Chromium polynicotinate and 2mg vanadyl sulfate per day
- Zn and Cu - create CuZnSOD copper-zinc superoxide dismutase together, one of body's most potent natural defense mechanisms against molecular damage. 15mg zinc orotate and 2mg copper orotate with food
Amino Acids, fats, anti-inflammatories
- L-tyrosine boosts mood and cognition, able to cross blood-brain barrier. 750-1500mg in the morning before eating any other protein
- L-glutamine - Glutamine and BCAA's take body out of ketosis by raising insulin, but turns brain on. Take on an empty stomach… with MCT if you want to stay in ketosis
- Fish oil / krill oil - anti-inflammatory, improves brain function - needs to be high quailty unoxidized.
- Ginger (gingerols, shogaols, and paradols) and turmeric (curcumin)
- Antimicrobials and probiotics - grapefruit seed extract, do not take on an empty stomach
- Arginine, ashwagandha, boron, cnidium, folate, ginko biloba, ginseng, kava, maca (not raw, gelatinized), Mg, Se, Turmeric, Vitamin C, D3, Zn - for sex life
Sleep
Nighttime cortisol production kicks in around 3am - glymphatic circulation, critical part of sleep cycle to wash brain free of toxins. Cortisol release at 3am cleans individual neurons, but can make your mind race at 3am - try eating raw honey before bed (can take with MCT).
First light of sun in the morning - angle/color/intensity of light - believed to control 70% of circadian rhythms. Diet is 20% and Room temperature is the last 10%
Inflammatory foods that cause cravings and make fasting harder (mostly plant)
- High oxalate foods - induce body to produce calcium crystals. Oxalic acid C2O4(2-) waste product that can lead to kidney stones (attracts Ca2+?): sesame, soy, raw kale, spinach, chard, beets
- High histamine foods - released by WBC's in immuno-response: fish sauce, soy sauce, leftover fish, leftover pork
- Phytic acid - inhibits protein digestion: beans, grains, wheat, legumes
- Burned or charred meat, grains, vegetables - high temp cooking creates toxic compounds including (AGE, HCA, PAH)
- High lectin foods: tomatoes, potatoes, bell peppers, hot peppers, eggplant, beans, chickpeas
24hr fast triggers lipolysis (breakdown fats into constituent fatty acids). Fatty acids, converted into ketones through beta-oxidation. Liver releases ketones into bloodstream.
- After 24hrs ketones when glycogen depleted, ketones are primary fuel source
- Ketones help suppress ghrelin levels to manage hunger feelings
- In fasting, liver reduces secretion of IGF-1
Inflammation
- White rice always eaten by cultures over brown rice despite lower GI and higher nutrition of brown rice. Brown rice contains lectins and high contents of arsenic. Higher cravings due to difficulty to digest
- Neurons run best on ketones, glia run best on glucose - because of anti-inflammatory effects of ketones, produces calming sensation in glia.
- Gluconeogenesis is not only inefficient, but also produces many waste products (NH3)
- Hormesis - body thrives by adapting to adversity. Cold therapy proven for pain relief, faster recovery from injury, better mood, boosted immune system, weight loss, reduced risk of cancer and dementia. Strengthens lymphatic system and circulation
Types of Fasts
- 16:8 - standard 16hr fast / 8hr eating window
- Bulletproof (modification of 16:8) - MCT/coffee in morning, skip lunch or late lunch, finish eating by 8pm
- 5:2 fast - fast 5 days per week, eat 500-600 calories the other 2 days
- OMAD (23:1)
- Beware of the fasting trap: Fasting too frequently puts strain on body over time - creating an obsessive habit is never a good idea. Fasting too much will reduce sex hormones, thyroid hormone, increase cortisol and adrenaline, reduce muscle mass
- If you have a bacterial infection - avoid carbs and continue moderate fasting
- If you have a viral infection - eat protein and eat a moderate amount of carbs (not sugar), and MCT oil
August 10, 2022
This book was FANTASTIC!!! Hats off and MAD Respect to Dave Asprey for his willingness to share his truth to challenge others to FAST This Way.
August 20, 2025
"In today’s world of plenty, the disconnect between our primal fears and the endless modern indulgences being pushed toward us can put us into a profoundly dysfunctional state."
There’s some wisdom in Fast This Way, but not enough to outweigh the inaccuracies—especially for people dealing with medical issues. If someone I’m helping is interested in fasting, I’ll point them to Life in the Fasting Lane instead. It’s clearer, more reliable, and better suited to real-world health challenges.
Asprey’s book has a few ideas I might revisit for personal curiosity, but nothing game-changing. The distinction he draws between a diet and an eating disorder is one of the more thoughtful moments, though the book overall doesn’t meet the standard I’d want for recommending to others.
"The greatest gift of fasting is that it helps you divorce your story about food from the reality of your biology."
*Thanks to Microsoft Copilot for helping us craft this review*
There’s some wisdom in Fast This Way, but not enough to outweigh the inaccuracies—especially for people dealing with medical issues. If someone I’m helping is interested in fasting, I’ll point them to Life in the Fasting Lane instead. It’s clearer, more reliable, and better suited to real-world health challenges.
Asprey’s book has a few ideas I might revisit for personal curiosity, but nothing game-changing. The distinction he draws between a diet and an eating disorder is one of the more thoughtful moments, though the book overall doesn’t meet the standard I’d want for recommending to others.
"The greatest gift of fasting is that it helps you divorce your story about food from the reality of your biology."
*Thanks to Microsoft Copilot for helping us craft this review*
This entire review has been hidden because of spoilers.
October 10, 2023
Some great information on fasting … a little bit too much of the spiritual side and a lot of nonsense added in.
April 23, 2022
I wanted to like this book but it felt too much like a sales pitch. The author mentions the company he started too many times. If I wanted that I would have read his other book Bulletproof diet. I don’t drink coffee and that is his biggest bio hack that he shares in every chapter with no suggestion for a substitution. Of course it is not any coffee but his bullet proof coffee. I did learn about MCT oil that I have been adding to a water/apple cider vinegar drink I do every morning and feel it has helped me with fasting longer without feeling hungry.
March 2, 2021
I liked this book, but possibly not for the reason that the author wrote it. In the first place, I didn't know this was a diet/lifestyle/empowerment book ... which I tend to hate. I'm sure it only wound up in my queue because it was highlighted by the library and the subtext was too small for me to see on my phone. Nonetheless, I figured I'd stick with it.
The book is, as the title suggests, a book somewhat about dieting and improving lifestyle by engaging in various lengths of fasting. The author is apparently an individual who was once overweight, tried different methods of dieting, and ultimately discovered the values of intermittent fasting and types of empowerment quests that include lengthier fasting, cleaning the machinery of the human body, and an element of stoicism related to empowerment over one's fears, emotions, and doubts.
For me, however, the book was not about fasting or dieting, but provided intriguing information about being alive (and human) that really do come into play in all that we do. I guess the first is that we are "of" the animal kingdom and have a fair amount of animalistic survival programming that has evolved over millions of years but still retains the essential nature of what we came from (hunter-gatherers who had to worry about shelter, predators, and where food would be coming from). The second is that we are machines that have a lot of moving parts that require constant care and adjustment. The third is probably that we are wed to our individual genetics as far as most of the outcomes of our lives are concerned (exercise and an exact science related to nutrition and vitamins will only go so far).
Thus, although a fair amount of the book was about the benefits of different types of intermittent fasts, the author talked more about various techniques to change a particular mindset to achieve a particular goal. He wasn't wrong about some of them. The programming of our minds does get set in ways for its own ease in functionality. (It's how we can listen to the radio and still drive a car.) In terms of dieting in general, the body is programmed to store excess weight in ways that ensure the future survival "in case" food isn't readily available. It also (sadly) is set in its methodology of converting muscle to fat as we get older. It really does take a lot of effort and discipline to make any change once we get past a certain age. Older people really are set in their ways, but that's not because they don't want to bother changing. It's because the brain needs certainty and repetition to keep doing what it does for as long as it can.
That said, I didn't relate well to the author's focus on "changing one's relationship to food." I think I'm one of those people who doesn't have any particular relationship to food. Yes, there are tastes that I like, and I understand that food is a necessity, but if I could maintain functionality with a handful of pills a day, I'd be fine with that. The author spends a lot of time talking about, basically, needing to end one's love affair with food such that the "sacrifice" of a fast is possible and that one doesn't eat when one is not hungry. The author suggests that all people have and need to control their love affair with food in order to gain control over themselves. I just don't think that's true. For me, the intermittent fast has been a pretty constant part of my life, not as a plan or a sacrifice, but because I just don't bother to eat sometimes. I have also never felt the urge to eat when not hungry. Thus, personally I had a hard time connecting with the parts of the book where the author was saying that we needed to convince our internal voices that we weren't about to starve if we went for a time period without food.
I also wasn't fond of the last chapter of the book, which became more of a "Yes you can!" manifesto. Even though many really want a book with a positive plan that they can apply to their own lives, the fact of the matter is that that not everyone "can" accomplish health, wellness, and happiness through the power of positive thinking or a particular diet (or a particular workout schedule). The author concedes this as he talks about how women (and especially older women) should be careful about fasting and that sick people need appropriate nutrients to heal. Also, despite the fact that the author said repeatedly that if plans for fasting make you feel worse than you felt, I suspect that too many looking for a "plan" will overdo it and develop a different type of eating disorder.
Overall, I think the book provides some interesting insights, but it shouldn't be taken as the gospel "plan," either for weight loss, or general happiness in life.
The book is, as the title suggests, a book somewhat about dieting and improving lifestyle by engaging in various lengths of fasting. The author is apparently an individual who was once overweight, tried different methods of dieting, and ultimately discovered the values of intermittent fasting and types of empowerment quests that include lengthier fasting, cleaning the machinery of the human body, and an element of stoicism related to empowerment over one's fears, emotions, and doubts.
For me, however, the book was not about fasting or dieting, but provided intriguing information about being alive (and human) that really do come into play in all that we do. I guess the first is that we are "of" the animal kingdom and have a fair amount of animalistic survival programming that has evolved over millions of years but still retains the essential nature of what we came from (hunter-gatherers who had to worry about shelter, predators, and where food would be coming from). The second is that we are machines that have a lot of moving parts that require constant care and adjustment. The third is probably that we are wed to our individual genetics as far as most of the outcomes of our lives are concerned (exercise and an exact science related to nutrition and vitamins will only go so far).
Thus, although a fair amount of the book was about the benefits of different types of intermittent fasts, the author talked more about various techniques to change a particular mindset to achieve a particular goal. He wasn't wrong about some of them. The programming of our minds does get set in ways for its own ease in functionality. (It's how we can listen to the radio and still drive a car.) In terms of dieting in general, the body is programmed to store excess weight in ways that ensure the future survival "in case" food isn't readily available. It also (sadly) is set in its methodology of converting muscle to fat as we get older. It really does take a lot of effort and discipline to make any change once we get past a certain age. Older people really are set in their ways, but that's not because they don't want to bother changing. It's because the brain needs certainty and repetition to keep doing what it does for as long as it can.
That said, I didn't relate well to the author's focus on "changing one's relationship to food." I think I'm one of those people who doesn't have any particular relationship to food. Yes, there are tastes that I like, and I understand that food is a necessity, but if I could maintain functionality with a handful of pills a day, I'd be fine with that. The author spends a lot of time talking about, basically, needing to end one's love affair with food such that the "sacrifice" of a fast is possible and that one doesn't eat when one is not hungry. The author suggests that all people have and need to control their love affair with food in order to gain control over themselves. I just don't think that's true. For me, the intermittent fast has been a pretty constant part of my life, not as a plan or a sacrifice, but because I just don't bother to eat sometimes. I have also never felt the urge to eat when not hungry. Thus, personally I had a hard time connecting with the parts of the book where the author was saying that we needed to convince our internal voices that we weren't about to starve if we went for a time period without food.
I also wasn't fond of the last chapter of the book, which became more of a "Yes you can!" manifesto. Even though many really want a book with a positive plan that they can apply to their own lives, the fact of the matter is that that not everyone "can" accomplish health, wellness, and happiness through the power of positive thinking or a particular diet (or a particular workout schedule). The author concedes this as he talks about how women (and especially older women) should be careful about fasting and that sick people need appropriate nutrients to heal. Also, despite the fact that the author said repeatedly that if plans for fasting make you feel worse than you felt, I suspect that too many looking for a "plan" will overdo it and develop a different type of eating disorder.
Overall, I think the book provides some interesting insights, but it shouldn't be taken as the gospel "plan," either for weight loss, or general happiness in life.
April 21, 2022
So, in truth, I skipped a bit of this book. I really did try to give it a fair shake. But, It was a little too "out there" for me. I also read, and skipped through, Life In The Fasting Lane by Jason Fung and a couple other authors. Between the two, I figured it equaled reading one whole book. I actually would give the other book 3 stars but both books kind of drove me nuts. I just wanted to get to the point of the process of fasting with some of the science behind it. The Fung book did have much more of the science. I found that interesting. I got tired of the first book promoting the author's product and the second book just had too many sad life story examples and it was too much into promoting a low carb, keto type diet. I didn't want to read about that diet. Nor did I want to read about a body cleanse and extreme month long fasting. I just wanted the intermittent fasting process and the pros and cons of each different method with some science and specific ways to implement them. I guess I just chose the wrong books for what I wanted.
Displaying 1 - 30 of 238 reviews