Ketosis and Athletic Performance: More Than Fat Loss

The above video is a presentation by Peter Attia, M.D.

His talk is somewhat technical, but I always write blog posts hoping 20,000 people will *love* them, not that 1,000,000 will *like* them.

In this presentation, you will learn (in my words, not Pete’s):

– More about nutrition than most MDs learn in med school.

– How ketosis-adapted performance can aid fat loss and high-altitude resilience.

– Why the calorie estimates on treadmills and stationary bikes are complete BS.

– The three primary systems of energy production and basic organic chemistry, both of which aid understanding of all athletics.

Even if you struggle a little with vocabulary, the first 30 minutes are well worth watching a few times.

This talk made me immediately want to jump back on the Cyclical (or “Cyclic”) Ketogenic Diet (CKD), which was conceptually introduced to me in 1996-1998 by the writing of Lyle McDonald, Dr. Mauro Di Pasquale, and the late Dan Duchaine. It’s incredible for simultaneous fat loss and lean muscle gain, though perhaps needlessly complicated for non-athletes.

I usually limited the carb-reloading period to 12-18 hours after a glycogen depletion workout on Saturdays, though I experimented with moderate Wed night carb-ups while training for sports like kickboxing.

If you’ve experimented with ketosis, what was your approach and experience? Pros and cons?

For additional reading, I suggest the following posts by Dr. Attia:


Odds and Ends:

This week, I’m using my birthday to change the world with @charitywater. Please click here to take a look. You could do the same.

The Tim Ferriss Show is one of the most popular podcasts in the world with more than 900 million downloads. It has been selected for "Best of Apple Podcasts" three times, it is often the #1 interview podcast across all of Apple Podcasts, and it's been ranked #1 out of 400,000+ podcasts on many occasions. To listen to any of the past episodes for free, check out this page.

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219 Replies to “Ketosis and Athletic Performance: More Than Fat Loss”

  1. So, I heard don’t eat bread, rice or pasta for general meals. If 3000cals are required what is he eating as I think I missed this part of the presentation. thanks

  2. I was diagnosed with Anklyosing Spondilytis in January. I immediately began experimenting with my diet based on anecdotal success stories I read online. After many months of experimentation I settled on a diet that consists entirely of meet and green vegetables with a small amount of cheese, beer, and wine. The diet has reduced my inflammation levels from 7x the normal value to currently about 1.5x the normal value. So still a little ways to go but it has made an enormous difference.

  3. Started the Keto Diet after hearing it from a friend. On a 5’7″ frame I went from 260lbs to 238lbs in 8wks, with zero exercise. Strictly limited myself to <50g carbs per day while maintaining 1800 calories.

    Now I've joined a gym and I'm excited to try this out with exercise. Going to start slow and steady…

    1. I train in mixed martial arts and have competed in Kickboxing while in ketosis. I can honestly say that if a dedication to getting enough calories is there, my performance has improved in every athletic marker: aerobic fitness, anaerobic fitness etc. I think it has improved because my system is generally less stressed from carbs which I am clearly intolerant to. It takes some adaption time-the benefits of ketosis for me have emerged over a stretch of a year but they are well worth it for me.

  4. I was friends with Dan Duchaine. He was a man ahead of his time. Militant Bodyopus was my bible when I was a compeitive powerlifter.

  5. Thanks for the post and all of your amazing work. I follow Peter closely now and his work at NUSI. What is terrific, I became aware of him through your podcast last year. I have been CKD for several years and for the last 4 months have been Keto, my experince has been life altering…the cognitive buzz and empowered flow state, is extraordinary. The other significant addition I highly recommend is cold water therapy, and of course without saying, the most important addition to performance…daily meditation practice. Thank you Tim, I owe most of all my performance enhancements to you! Your work has changed my life and I have changed the lives of many others! I am in your legion of learners and teachers, your legacy lives!

  6. I tried It a few years ago and I had the most energy I had ever had in my life. But it was a bittersweet experience because it made me gain weight. I was eating a lot of heavy cream and eating when I wasn’t hungry if my ketones got too low. I used the urine strips. I fell off the wagon and my energy went back to shit which really sucks because I’m only 34!! With no kids!! Now I’m excited to try it again for the THIRD TIME. wish me luck 😉😉

  7. I learned all about Ketosis from Peter Attia’s website and ultimately lost 20lbs of fat and gained 7lbs of muscle in about a 2 month self-directed workout/weightloss program. I like to rock climb and saw my abilities jump from V2 to V6 in that short period of time. Here’s my report of how I did it:

  8. I did keto for 10 days, it did bring my blood pressure down to 118/70, but I know it’s not a diet for life. But if I look back to the time before I relied on driving a car everywhere and to using the computer, 1995, I was very slim and had a six pack, I did eat rubbish all the time, drank plenty of beer, but I was not sitting at a PC for many hours at a time.

    Well fast forward to 2015, and I am still on the computer! But also 20 kilos heavier and wider…..the car and the computer are the problem! Anyone care to argue?…..please do.

  9. Hey Tim,

    I’ve been doing a lot of research in both the Slow-Carb diet and the Ketogenic diet. How would you compare the two?

  10. I have been in Ketosis for about 3.5 months now. I tried a 5 day fast but I could barely get past day 3. I wasn’t even hungry, my mind was playing tricks on me… But, I noticed that even after some beer binges with friends, the next day my Ketonix shows that I’m still blowing enough Acetone to show that I’m still in Ketosis…

  11. I personally like and continue apply many of John Kiefers readings regardless of misuse of a multitude of citations. Application has been my personal experiences and others I train. Carb Back-Loading supports solid glycogen replenishment and the following the ultra low carb regiment majority of the day allows me to push my HR, helps my CNS recover, and not gain much if any fat. I do like movements that keep my HR <60% such as Ido Portal Movement Method to tax every muscle group without taxing my CNS much. HIIT, CrossFit, and other like concepts will require carbs however if you sustain consistent intake of dietary fats and protein through gluconeogenesis the body should have plenty of available glucose as solid energy source for workouts. Carb Back-Loading works very well for sustaining muscle volume and lean muscle tissue without much if any fat tissue accumulation if any.

  12. My biggest struggle is afternoon munchies. If I feel like I’m dragging and low on energy, I used to turn to the carbs and sugar. So that was my biggest road block. I’m still learning, though. I use a ketone supplement (beta hyroxybutyrate) that really helps with the cravings and energy. I also would like to see more resources on what to buy at the store. I need to get more keto-friendly foods that I like and know I would eat,

  13. Thoughts on Dr. Jacob Wilson’s research on ketosis (and everything else he does on body composition, for that matter)?

  14. I’m an ultrarunner and a HW developer so I jumped right into ketosis two years ago. A diet with so many ways to monitor progress was really appealing to me. I certainly had plenty of issues staying in ketosis when something as simple as an avocado can knock you out. I just finished building a portable breath meter that monitors acetone and generates a ketone mmol/L value. [Moderator: link removed]

  15. I struggle with fueling around ultra marathons while on ketosis. Pre-race would you want to carb up a bit? In race how what is an ideal low carb fuel. I would prefer to use real food over products. Post race would you rather be in ketosis for recovery or replace all that spent glycogen?

    My current solution is to use vegetables for carb loading pre/post race meals in the slow carb fashion. Also using chia as my primary in race food due it’s weight, fiber and fat ratio. Still need a lot of electrolytes so Sucees tabs typical 1-2 an hour.

    I monitor my blood glucose and ketones daily. It surprises me to hear that people are using piss stix as indicators as that is a very limited tell as to what is going on.

  16. Thanks Tim for sharing this useful presentation and your experiments in general. For over 14 months I´ve lived in ketosis without any cheat days and have never felt so good before. Besides loosing fat, I am more energetic and sportive which directly influenced my business and private life. I was not aware that glucose had been influencing my mood so much. Tell me please, do you think one can live all her life in ketosis without any harms?

  17. Hey TIm, my wife is trying the slow-carb diet and struggling a lot with cravings (pizza, donuts, etc.) Is there anything that you’ve found that helps?

  18. I know this is an old thread, but I figured it’s worth a shot anyway. I’ve been out if the gym for roughly 10 months, so I’m effectively starting from scratch. I’ll be picking up where I left off using the 5/5 method 3 days a week (push, pull, legs) as described by Tim in either geek to freak or Occam’s protocol, I can’t remember. I’ve also become really excited to try a keto diet for the first time. Basically what I’m looking for is the 20 pound recomposition described in 4 Hour Body, and I’ve got 6 weeks to do as much damage as possible. A couple of questions here:

    Any problem getting into ketosis for the first time at the same time as starting a gym regimen, besides what I’m guessing is a certain induction flu?

    Any suggestions about post workout meals in this situation? Maintain very low carb and focus on caloric surplus?

    I’m sure I had more questions, buy this is a good start. Thanks in advance for any help.

  19. I’ve been doing a standard keto diet for about 4 months now with great results. What I want to know now is whether this can be coupled with Occam’s protocol to maximize muscle gain and minimize fat gain

  20. Thank for this lost Tim. After 30 years of a typical bodybuilder diet ( cycling starchy carbs, med to high protein ) I finally utilized an Intermittent Fasting approach ( 50% fat, 25% carbs, 25% protein ).. I was amazed at how easy it was.. I def noticed better natural energy & focus.. In 8 weeks I gained 3 lbs. on the scale while losing 2 inches off my waist. My testosterone level increase by 200 to 822.. Amazing to me for a 50 year young guy that is lifelong drug, hormone & ped free.. I have become hooked on the benefits of a personalized IF program.. And now have all my clients utilizing it.. And I just signed with a publisher to write a book about it..

    1. That’s a huge hormonal improvement for any adult age. While your book is forthcoming, will you share the length (hours) of your intermittent fasts?

  21. Actually carb refeeds are starting to appear in the research pointless and counter-productive (see Dr. Jacob Wilson’s work on this). It is a misunderstanding of how ketosis works – a primary adaptation is novel/upregulated gluconeogenic pathways. The great misunderstanding – one is NOT glycogen depleted when one is in ketosis. Volek and Phinny, among others, have shown this. Eric Westmann has the numbers – a 170 pound man can make 800 cals of glucose a day in ketosis, mostly from non-protein substrate. While your glyocgen might not be topped off, it is never empty either except in very specific sport situations – high volumes of high VO2 max work at high cal/min rates. A keto athlete might be in a better glyocgen state most of the time compared to a high carb athlete because glucose efficiency outstrips lowered storage of glycogen. My 45 year old wife competes in Figure in year round ketosis with no carb refeeds. Maintains 12% BF off season comfortably on 150g fat, 30g carbs, 135g protein and at 124 pounds benched 140 in a bench-only powerlifting competition to win overall. She can do 10 bodyweight pullups and do dips with a 45 pound plate on a belt. No need for carbs.

  22. Out of ketosis on Saturday morning. FASTEST way back into ketosis, nothing off the table? Is one day possible?

  23. I’ve been in ketosis for 4 months and lost 35 lbs and I’m feeling great. I listened to all the relevant podcasts with Dr. Peter Attia and Dom D’agostino, and those were all super helpful. Just today I discovered that Dr. Attia and Gary Taubes are no longer on the NuSI website, and that a NuSI study did not support one of their hypotheses. I’d love to know the latest on what the study showed, etc.

  24. Hi guys, Is it possible to gain a decent amount of muscle on the cyclical ketogenic diet whilst weight training as I am struggling to find any research on the topic?

  25. Listening to your podcasts, I twice heard that you are having gut flora problems after antibiotics. I won’t go into how I know this, but you should try 1/2 raw milk (you can get safe stuff at health food stores in California no problem) 1/2 fresh squeezed grape juice to make a quart. Drink it all right away as it begins to curdle immediately. Try it for a week. If your measurements don’t change or you don’t feel a difference, call me an asshole, but you have nothing to lose. I hope it helps!

  26. The ketogenic diet really does work. Thank you for posting this. I chanced on this video on your blog just in time. I started my nutritional transformation in early 2017 with the ketogenic diet and a daily exercise habit. I was a bit of a couch potato and never really got into sports. I had exercised sporadically in the past.. weights and cardio at the gym, doing different traditional forms of yoga (hatha, Iyengar, Sivananda) and dance workouts. This time, I started jogging at 4:30am every morning and doing bodyweight exercises in the evening. I cut sugar out completely (including natural sugars) and followed keto as sincerely as possible. Imagine my surprise when I started losing fat and visibly gaining muscle within weeks. I am 34-year-old woman weighing 61kg when I started. It’s under 2 months and my weight has dropped to 54kg. Even more surprising was the fat loss. My body fat percentage was upwards of 27 when I started. last week, it was 20.5. My goal is 18% body fat by end of May 2017 and I am more and more sure of reaching it.

    I dropped dress sizes too. I have gone from a medium size to a Large, XL and even XXL in my late 20s. The XXL phase was the most depressing. My waist was about 38 then. After getting on the ketogenic diet, for the first time in life, I am a US XS (that’s extra small!). I am studying nutrition too and as of now, the Keto diet looks pretty balanced (the only thing I miss is fruit). Once I reach my weight loss (50-53kg) and fitness (<18% body fat) goals, I will switch to a Paleo-keto diet.

  27. Haha, this post is old and no one will see this comment, but it was fun to hear Dom D’Agostino asking Dr. Attia about exogenous ketones. We all know what Dom has shown regarding the power of exogenous ketones, and how spot on both guys have proven to be as far as disease prevention and treatment with keto as an adjunct. But more to the point, I truly believe that almost anyone would find the extreme restrictiveness of keto to be almost irrelevant if they first experienced the effects on energy/fatigue. It also seems, as someone who has struggled with binge eating, that the hunger alleviation of keto confers a massive advantage to someone struggling with weight-loss and is almost completely ignored when different diets are compared in studies.

  28. Informative video and love the link to the cycling of the Keto Diet. I’ve been looking at ways to incorporate ketosis while gaining muscle and not gaining any fat for my bulking periods. Tim has created great articles and parts in the 4-Hour Body of how to get down to roughly 8% body fat but at least from my knowledge hasn’t touch on how to naturally (without steroids) get down below 5% body fat. I would love for Tim to post or have someone on the podcast about this but does anyone else have any suggestions that worked for them?

  29. Have you heard of the pesKETOrian diet? Probably not, because I just invented it. It’s a keto diet only I just eat fish for proteins. A few exceptions: grass fed butter, heavy crean, and pasture raised eggs.

    Can you please ask Dr. Attia if this is genius as I suspect, or if I’m wasting my time?


    Mark Cafiero

  30. I’ve read about CKD, it is a solution to long-term Ketogenic Diet success. It allows the practitioner to break ketosis from time to time, therefore enjoying carbs, while resetting the metabolism. CKD is a very challenging type of ketogenic diet, which is why it is not recommended for beginners.

  31. [Moderator: Twitter link removed.] During a routine physical, my doc announced to me that I was pre-diabetic. I commented something like “wow, I’m not even overweight!”. He grabbed my stomach fat and said, “See this? This is a gut. Lose it or else you will become full-blown type II diabetic”. I started the keto diet that day. Today, 6 years later, I’m running faster skiing better than I did in college, and my life is changed. Still keto and I enjoy a cheat on major holidays and some birthdays only. IF almost every day. Life: changed.

  32. Hi Tim! I love your podcast and have learned much from it. Thanks for that, your TED talks, and 5 bullet Friday. Random place to post this, but seems as relevant as any: I would love to see (hear) you interview this scientist: [Moderator: link to Lisa Mosconi’s website removed.], not least because menopause is hardly considered a cool topic and I would like to see that changed by an arbiter of cool such as yourself, but also because I know you are fascinated by neuroscience and diet and her work combines these…could be an epic conversation.

  33. Did keto for a few months. Lost 20 pounds; bad cholesterol shot up. Used it like a blunt tool for weight loss; would do it again if I could keep the cholesterol down.