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Discussion Starter #1
Started on a Keto diet end of last December and so far it's been great. I've lost weight and energy levels are very stable, more so than using carbs as energy.

Anyone here with Keto diet / endurance racing experiences? Signed up for two races this year (single speed category), one is a 24hr race - approx. 9 miles/900ft elevation per lap.
 

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XCdude
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Read all the work, by Dr. Dan Plews leading the charge on exactly this. Added all the names above.
 

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Up In Smoke
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There is a movement of ultra-marathon runners on keto diets. Worth looking into for endurance stuff, but detrimental to high intensity efforts. Pick your poison.
 

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The longer you are on keto the better you will perform on it. My peak intensity is almost as good as when carb fueled. But I can ride fasted if I want to and not bonk. I've done keto may times and have stayed on it for over a year. Once adapted you can ad more carbs during ride on race day. But requires some research.
 

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Train low / race high [carbohydrate] has its merits, even for MTB. Bear in mind though that MTB is inherently intense, even when you are going easy. The demands are different than most of what has been investigated in the literature.
 

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Thanks for the information everyone. I think I'll need to experiment to see if an all protein diet will work during the race. I'd still like to hear from someone that has fueled with protein for a 24hr solo MTB endurance event. I know everyone is different, but there doesn't seem to be much information out there.
 

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There might be anecdotes from 24 hour racers on carbohydrate restricted diets, but proper research on this specifically would be difficult to organize! Either way you approach training, you will still want carbohydrates during the race.

You might find this podcast episode helpful (my co-host did his PhD on low cho diets and ultra-endurance performance): https://anchor.fm/performanceadvant...-with-Expert-Dr-Will-OConnor-eau79l/a-a1hp5gj
 

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Thanks for the information everyone. I think I'll need to experiment to see if an all protein diet will work during the race. I'd still like to hear from someone that has fueled with protein for a 24hr solo MTB endurance event. I know everyone is different, but there doesn't seem to be much information out there.
Joe Rogan talks about Keto a lot with his podcast guests.
 

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Thanks for the information everyone. I think I'll need to experiment to see if an all protein diet will work during the race. I'd still like to hear from someone that has fueled with protein for a 24hr solo MTB endurance event. I know everyone is different, but there doesn't seem to be much information out there.
1) You're not going to "fuel" yourself with protein. You'll be relying predominantly on your stored fats and ketone mobilization, as well as stored glycogen.

2) It is possible to fuel 24+ hrs of aerobic activity from your fat stores, if you keep your intensity levels low enough. At higher aerobic intensities, you will shift to glycogen/glucose utilization. All keto-adaptation does is shift where that transition in substrate utilization occurs. Given the elevation gain per lap, and the fact you're on a single-speed, there will be plenty of instances where you're going to dip into your glycogen stores. Once you burn through those stores, you're going to be left in a mental fog wondering what the heck went wrong. So, even if you're planning on a ketogenic diet strategy (which is absolutely NOT all-protein...), I'd suggest having a back-up plan unless you plan to ride slow the entire race.

3) Is this your first 24-hour solo race, or just the first on keto? Maybe keep a note-pad in the pits and jot your perceived energy level/exertion each time you stop in to refuel/replace bottles, etc. If you have HR and power data, you may able to approximate the intensity level that keeps you out of the red, or at least manage to capture approximately when you've burned through enough glycogen to impair your performance, mood, mental clarity, etc. (granted, none of this is a substitute for actually calculating substrate utilization via indirect calorimetry). It might be useful data to help you prepare for the next 24-hour race...
 

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There is a great book on the subject. The Art and Science of Low Carbohydrate Performance, by Jeff S. Volek, PhD, RD, and Stephen D. Phinney, MD, PhD.
 

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Discussion Starter #11
1) You're not going to "fuel" yourself with protein. You'll be relying predominantly on your stored fats and ketone mobilization, as well as stored glycogen.

2) It is possible to fuel 24+ hrs of aerobic activity from your fat stores, if you keep your intensity levels low enough. At higher aerobic intensities, you will shift to glycogen/glucose utilization. All keto-adaptation does is shift where that transition in substrate utilization occurs. Given the elevation gain per lap, and the fact you're on a single-speed, there will be plenty of instances where you're going to dip into your glycogen stores. Once you burn through those stores, you're going to be left in a mental fog wondering what the heck went wrong. So, even if you're planning on a ketogenic diet strategy (which is absolutely NOT all-protein...), I'd suggest having a back-up plan unless you plan to ride slow the entire race.

3) Is this your first 24-hour solo race, or just the first on keto? Maybe keep a note-pad in the pits and jot your perceived energy level/exertion each time you stop in to refuel/replace bottles, etc. If you have HR and power data, you may able to approximate the intensity level that keeps you out of the red, or at least manage to capture approximately when you've burned through enough glycogen to impair your performance, mood, mental clarity, etc. (granted, none of this is a substitute for actually calculating substrate utilization via indirect calorimetry). It might be useful data to help you prepare for the next 24-hour race...
Thank you for the information. Yes, this is my first 24hr race. I started a keto diet end of last November to lose weight for this race, and a couple others this summer. If I follow your advice correctly, it sounds like I should plan to have carbs available to sustain 24hrs.
 

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Follow Dan Plews, Paul Larsen and Pete Attia all the information you need they have it.
 

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Found I just couldnt stay hydrated at all with keto and had zero intensity.


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Dr. Dominic D'Agostino is another one that has LOADS if information on low carb/high fat diets. TONS.
 

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I've never done a 24hr endurance race. I've done a ton of 6-10hr 10'K climbing rides and a few 12hr rides on keto. I finished last year with a White Rim one day and I've trained for the 12hrs of Mesa Verde this winter but that got cancelled cause of the pandemic and all. I am not a XC racer. But I'm happy to share my keto cycling experience. YMMV.

I've been low carb since 2014 and strict keto for 2 years. My general impression is that it takes a long time to fully adapt to keto. It took me about 6mo to be really comfortable on longer efforts and 9mo to be able to push on longer efforts. I am more of a eggs, nuts and avocado Keto vs a dairy/ red meat. Not a vegetarian, not even close. But I try to maximize monounsaturated fats for baseline energy.

For longer rides/ more relevant to a 24hr race. For the most part I drink water on rides up to about 4-6hrs. I feel best after about 4hrs. Beyond 4-6 hrs I like salty fatty snacks like pork rinds, nuts and very dark chocolate. I've also had very good experience with the UCAN super starch bars. I feel that I can dig deeper, longer and more often on a keto diet vs a normal diet. But as has been said there is a definite limit to power out put on keto. For longer efforts this is totally irrelevant though, for me. I simply am not strong enough to get any where near max power during a big ride for any length of time. My pace on a long ride is much slower than a 1-2 hour burner. So I don't miss the top end. I think having a lower top end on long efforts is self protecting. I can diesel along at a pretty good clip. But sprints and such are just limited. So I don't/ can't burn all my matches too fast. Not sure how that would translate to a single speed bike. I just down shift and spin. Until there is no spinning to be done. Then I mash my granny gear. Some hills are steep.

If I will be pushing hard, like a 1hr hill climb effort for time, or a 1hr threshold effort on the Zwift bike I simply need carbs beyond 35min. I have not been able to extend that time frame with MCT oil, or fasting or supra threshold efforts fasted. At threshold and above, even well adapted on keto you are making lactate, by definition. Therefore you are using glycolysis to rapidly generate ATP. And that means burning carbs. That said even during hard efforts you are generating more energy from fat than the not keto adapted athlete, making less lactate and using less carbs. So you don't need a ton of carbs to keep the legs turning. I find my recovery times are lower now than they used to be. This is true both on the bike and in the gym.

Overall, I think that nutrition is VERY individual. I have a few friends also on keto inspired partly by my positive experience. We all can ride harder, longer with faster recovery than on standard diet. We are all enjoying cycling more (and that is all that matters in this long post). We all used to suck down cytomax or what have you for rides, and we used to bonk and cramp and hurt for days. Now we drink water. But the details of our experience are as unique as we are. For you OP I really think the keto diet is essential (for many people but not all) for endurance races. My concern would be the time that you've been on keto and the anticipated hard efforts on the single speed. Just be mindful while training. And eat some carbs (I recommend UCAN) on race day and race simulating training.

Keto On!!!
 

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Discussion Starter #17
Very good information, thank you! I'll order and try out UCAN bars, thanks for the tip. My diet is also nuts, eggs, avocado, but also fish and chicken, some steak. Not into "dirty keto", excess fats. Keto has been more of a lifestyle change for me, I was a bread and pasta (carbs) guy. I'm down 25lbs and feel better\stronger, so far so good.

It does sound like I'll need to plan on eating carbs to maintain enough energy over 24hrs.
 

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I find it hard to believe you can keep the effort low enough riding singlespeed to not be burning through carbs like crazy.

I've raced a lot of endurance and ultra endurance events, both singlespeed and geared....and regardless of bike there's a lot of high intensity efforts. Without walking A LOT, there is absolutely no way to keep your effort level under a threshold intensity on a SS. Maybe with ultra endurance trail running that's different because you can actually hike uphill segments and keep your HR lower and not lose much time on the field. In my experience that's simply not reasonable if you want to be even semi-competitive. Whether it's 24 hours of old pueblo or colorado trail race....there's a lot of time spent above threshold and even at vo2 max power to keep momentum and simply get yourself up the climbs. Heck, with 24hop, you gotta legitimately do a 6min/mile running sprint at the gun to get to your bike to get a decent position going into the singletrack. Without a 1:1 ratio, there's no way you're not going well over threshold HR going up the first climb to the top of ten mile at the Breck 100. When you're 5+ hrs into these things, it's the guys that can still knock out 20-30min at or above threshold and hold a really high pace to the finish that go on to podium, not the ones that dial it back and keep their HR low.

All the science I've seen says carbs are king on the bike and are instrumental to pre-ride fueling, in-ride fueling and post-ride re-fueling. If you want to lose fat and be healthier, it's calories in/calories out and you gotta keep yourself at a deficit until the weight comes off. Eating lots of green things, colorful veggies, beans and things high in fiber/volume help to keep you feeling fuller and being healthier....which inherently means way less bread/pasta.
 

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It does sound like I'll need to plan on eating carbs to maintain enough energy over 24hrs.
I think so. Again, it doesn't take a ton of carbs to stay well fuels as a Keto athlete. And there is a dark side of too many carbs. While exercising you can burn a lot of carbs without a big insulin spike and staying well in ketosis. But if you do get a big insulin spike then fat metabolism drops off dramatically. And it is very individual. So best to practice. There is a lot of keto endurance info in the Iron Man world. I have not ventured there for a while but I'm sure you can look into it. Please share your experience as you train and race.
 

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All the science I've seen says carbs are king on the bike and are instrumental to pre-ride fueling, in-ride fueling and post-ride re-fueling. If you want to lose fat and be healthier, it's calories in/calories out and you gotta keep yourself at a deficit until the weight comes off. Eating lots of green things, colorful veggies, beans and things high in fiber/volume help to keep you feeling fuller and being healthier....which inherently means way less bread/pasta.
Calories in/ calories out has died 1000 deaths and still lives because it makes sense. But it doesn't work IRL. No one loses weight over any time period following that line of thinking. Carbon in/ carbon out is true for sure, conservation of mass and all that. But neither you nor I nor anyone outside of a physiologic chamber can measure carbon or calories out with any accuracy. And no one feeding them self out side of a rigorous study where all food is measured and provided can measure calories/ carbon in with any accuracy for more than a few days. Long term weight is dictated by hormonal balance of the body.

Carbs are king is true for the racers at the sharp end of the pro/open field. This is not up for debate. It is true. For the vast, vast majority of racers and riders I think (and have a large pool of anecdotal evidence to support it) that a low carb diet is better/ faster/ healthier.

Then there is the next question, and I have my answer for it, but real studies and proof still elude us. Are the people who are winning and eating carbs less susceptible to the negative effects of carbs and there for can more efficiently burn this fuel source? There is a big difference between the physiology of the top dogs and the mid pack. Even the mid pack of the Leadville 100, while they are elite athletes, they are not nearly the same as the top 10. In my experience drawing nutritional advice from someone with very different physiology as yourself is not a good road to go down. Exercise and training can be pretty well carried from one person to another. For nutrition this is simply not the case. Genetic differences, gut biome and our own interpretations of nutritional information make what works for one person unlikely to give the same results in another. My take is that the really fast racers have different abilities to burn and manage carbs than the mid pack. And that while the people who win the race do so by eating large quantities of simple carbs, the mid pack racers will be faster and healthier on a low (not no carb) carb diet and race program.

Likely different advice for different athletes. And I hope I'm not coming across as stand offish. I'm always looking for more info and new data points. If you are doing ultra endurance events and fighting for a top finish then you have very different physiology than me. I can do 10-12 hrs and go for a respectable finish. Podium is not on my radar. I'm just trying to show a different perspective that is based on elite athletes but not off the few at the very sharp end of the sport.
 
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