Welcome to the Empirical Cycling Podcast. I'm your host, Kolie Moore, joined as always by Kyle Helson, and I want to thank everybody for listening and ask you to please subscribe to the podcast if you haven't yet already, and assuming you probably have, please share the podcast. That's the best thing you can do. If you're enjoying what we're saying and you relate to what we're saying, share it with a friend. It really helps us out. Also, if you want to help us out with a couple bucks, we are ad-free, so you can donate at empiricalcycling.com slash donate. We have show notes for this episode on the website, including links to all of the studies that we're going to talk about. and possibly more, whatever comes up while we're recording. And if you have any coaching and consultation inquiries, if you have any questions or comments, just email me directly at empiricalcycling at gmail.com. Also check out the Instagram. We've got the weekend AMAs and the stories going on as of recording right now, but probably be gone by the time this goes up. That's at empiricalcycling. So if you want to check that out, give me a follow over there. So last episode, we talked about fats and carbs in order to address VLA Max. Check that out because that's probably the only time that we're going to talk about VLA Max on the podcast unless somebody asks in one of the Q&A episodes. So this episode, we're going to start a two, probably two-part series looking at the ketogenic diet. And this is going to lead us into the just general discussion of burning fats about... Because if we started the other way, like if we started with... you know like Fat Max type discussion we would have to we have to go there and then we would have to work backwards to oh why doesn't keto work right oh did I give it away oops sorry spoiler alert spoilers spoilers and so so we're gonna go the logical way at least in terms of the points that I think should be made to have a deeper understanding of this kind of stuff and so far I think on the podcast at least If it were me listening, because this is, you know, admittedly I'm a huge nerd, but this is the kind of thing that I got into biochem for, like this answers all the questions I had growing up, which was like, we can either take a lighter or, you know, put sugar in a pot and we can burn it at very high temperatures, but how do we get... energy out of it at normal temperatures in our bodies. Like these questions fascinated me. Like how does an Oreo become fat or a sprint across the yard or something like that? So now we're going to talk about fats a lot for the next couple episodes. So we've got a couple episodes dealing with fat previously in the previous last couple Watts docs. So I encourage you, if you have not heard them, to go back and listen to those. A lot of the episodes, again, scrolling through our old episodes, I'm like, man, 2,500 listens, that one deserves at least 5,000. So if you see a low listen episode that might be technical, it's probably worth listening to, in my opinion. So go check those out. So moving forward, Kyle, what are your thoughts so far on the fat aspects of this series? Maybe this is a good time to talk about the villainization of big sugar. Well, short of getting into some sort of long history lesson about sugar and foods and advertising and stuff, which by the way, if you ever want a fun watch is go find old cereal ads from like the 50s when they would advertise as added sugar being a positive aspect to the cereal. Anyway. I think that recently it's become quite popular to really people probably have known but it's become much more popular now to think about fat burning and being really good at fat burning and fat utilization as being really important in sports performance especially endurance sports performance and so hopefully this has given some people a little bit of a deeper insight into kind of how that works in your body. And like you said, how you turn an Oreo into a sprint across the yard or fat, depending on how many Oreos you eat. But this maybe gets taken a little bit too far when people start thinking, oh, fat utilization is good. Therefore, reliance on carbs and sugars must be bad. And you're like, well, that's not, it's maybe taking it too far, right? Like these things are not mutually exclusive. using fat well is a good thing. It doesn't mean that using sugar well or using sugar at all is bad. Yeah, and also, well, I think there's also an easy bad guy in this whole thing too, which is, you know, any kind of study that looked at, you know, high fructose corn syrup kind of things are associated with more weight gain and things like that. You know, because really... Not to spoil the next episode, but a lot of it comes down to calories in, calories out, and that's a good way to get in more calories than you need. And if you're eating stuff like beans and rice, you're going to get in less calories overall because you're going to feel so damn full. I had beans and rice for dinner yesterday. I got to my evening meal, and I was like, no, I was so full still. But anyway, the point is, if... Taken to logical extremes, we get to the ketogenic diet, right? Because if, like you said, if burning fats is good, how do we burn more fats? But then the question is, what are the other impacts that it potentially has on performance? And that's what we're going to look at today. We already kind of did an episode on this, by the way, a while ago. It had a very long and wordy title because I didn't know how to title anything snappy. I still don't, for the record, but getting better. But I didn't then either. Yeah. So we'll get to that episode. I've got a reference in here somewhere in our show notes for this episode. So we'll get to it. So let's start with what is ketosis? And if you want to talk about nutritional versus other kinds of ketosis, look that up online. There's a lot of good resources on that kind of stuff. So we're just going to go in for just exactly what do we need in this episode without kind of giving proper quote unquote lip service to people who seriously are proponents of this diet. So what is ketosis? So ketosis is a metabolic state the body is in because of chronically low glucose, blood glucose. So the name ketosis and keto, like what are these from? Like we've discussed this before, a ketone is a functional group in chemistry. So it's just a common thing that has certain... Common Chemical Properties across all ketones. So it's a carbon that's got two of its four bonds attached to a single oxygen molecule. And typed out in regular form, it just looked like C equals O. So that's a ketone. You see that, you think that's a ketone. So ketone bodies are just two types of chemicals that have ketones in them, and they are in a... in abundance when we are in ketosis, like in the bloodstream, and these can be measured. So the two of them are beta-hydroxybutyrate and acetoacetate. And these are very chemically similar based on whether or not we want to add or subtract an NADH, which would be the same way that pyruvate and lactate are similar in chemical structure and refer to Wattstock number 31 and 32 on that. Does that kind of make sense? Yeah. And for people taking notes at home or who maybe are unfamiliar, acetone is going to be probably the most common ketone you have heard of, but don't drink acetone. It's bad for you. But like nail polish remover or it's a common organic compound solvent or industrial solvent, but that's probably the one that people have maybe heard of in their day-to-day life. Yeah. Yeah. And so acetoacetate, like you probably are familiar with the word acetate, which is vinegar. So it's really just two like vinegar-ish molecules linked together and then you add or subtract a proton and electron and whatnot. So anyway, ketosis means you have ketone bodies in your blood or possibly urine and they've reached a certain level. And at this level, you are considered in nutritional ketosis. So this evolved as a mechanism for two things. First, a low carbohydrate availability in the environment. You know, like if you don't have any potatoes or fruits or anything like that to eat, you're mostly relying on animals and insects and things like that. It behooves your body to have a mechanism to be able to survive. And, you know, a lot like... Lactate to kind of have a way to use all this extra acetyl-CoA, which just becomes acetyl groups, and then you get acetyl acetate and beta-hydroxybutyrate. So it's pretty simple. You get excess of them. And if you have way too many in the mitochondria, of course, you are going to refer to last episode, you're going to overwhelm the fats transport mechanism across the mitochondria. Now in regards to performance, so what's the promise in ketosis or at least high-fat diets? Is it, you know, we're burning more fats during exercise? Why is this good? So I think a lot of people think about two things. Number one is weight loss, which we'll probably talk about next episode. And number two is going to be performance, which we're going to talk about this episode. So in theory, also burning more fats leads us to spare. Glycogen. Glycogen stores are limited and fat stores for practical purposes are unlimited. And the question is, does this help endurance performance by using more fats? Does this about cover most of it or did we miss a couple of things here? I think that basically covers it. I think that for some people, you may be able to tie together weight loss and increase performance, especially in something like... is cycling where there's an emphasis on watts per kilogram and I think in other sports like that involve a weight cut so that is like weightlifting or MMA or wrestling or boxing where you actually have to make a certain weight you can kind of Mix these two as well, where weight loss and sports performance are the goal, two simultaneous goals, and people turn to keto often. Maybe not often, but people consider keto for this sort of thing. Yeah, and I think also at this point, just culturally, it's, you know, what is it, November 13th in 20, what year is it, 21? Wow, 21 already? Oh, God. So I think I think we're past the keto craze by now and a lot of people have figured out a lot of people have probably tried it and it didn't work you know so I think we're past the past the crest of the keto craze but I'm sure it'll last sort of like the thought you know the what is it the common knowledge that lactate causes fatigue or acidosis or something like that I think it's entered into the popular sphere enough that people know that it is a strategy for weight loss and even people who aren't interested in sports performance or sort of being on the cutting edge of research kind of in the same way that the Adkins diet and similar things were the craze and the... Late 90s, early 2000s, I think that kind of paved the way for the keto stuff because that was the initial wave of these lower carb, higher protein, higher fat diets. Yeah, and I remember too in the late 90s, I was in high school and I remember one of our teachers, everybody was like, oh my God, he lost so much weight. And I was like, the Atkins diet. I was like, what's the Atkins diet? And they're like, yeah, you don't eat bread. It's like, oh, that sucks. Why? It's like, well, he lost so much weight. And it's like, oh, that's cool. What do you eat? And they're like, hamburgers, like no buns. It's like, oh, all right. And then as soon as he started eating bread again, just like gained weight immediately. But that's one of those like, you know, number on the scale type things because you've restocked glycogen and glycogen has a lot of water storage associated with it pretty quickly. So I think the other thing that, you know, besides, you know, anecdotal stuff like my high school teacher, There was good marketing, for lack of a better term. A good presentation of the keto diet during this time. And so I read a lot of the papers from this era, which was not long ago, actually. So I read a lot of the papers, the pro-keto for athletes things. and they had some very interesting kind of, I'm gonna disparage people again. I've learned not to do this publicly on the podcast, but I apologize. They had a lot of bro science type language, you know, like phrases like release themselves from carbohydrate dependence. You know, it sounds like you're throwing off the shackles of colonialism or something. Yeah, I think that is. One of those things where people look at it and they think like, oh, like the selling phrase is that your body only stores so much glycogen. So if you can do this high intensity, high performance exercise, not relying on glycogen and instead relying on fat, you have a lot more fat. Therefore, you're going to be so much better and your performance is going to be amazing and you're going to have tons and tons of endurance because you won't. Deplete Your Glycogen Stores. Yeah. Well, it's like, have you ever heard of eating? That's a thing. Well, I saw in one paper, I saw a table of the amount of energy by the total 1,000 kcal energy reserves that we have in the human body. And so it's 2,000 kcal in carbohydrates, plus or minus. That's a... Good Estimate. Fat is 35,000 kcal. And protein, I believe it was 30,000 to like 600,000 or something like that. But the scale, it was by 1,000 kcal. So you're looking at two versus 30 for carbs versus fats, which is like, oh, we've only got two. Oh my God. As opposed to like 2,000. 2,000 still sounds like a lot, you know? Right, yeah. And I think that is... One of those things where obviously someone made this plot to maximize the contrast between these two figures. Yeah. I mean, they also mentioned that phrases like research on keto athletes were quote unquote remaining hidden. You know, like it's like, you know, like the JFK files or something like that. And it's like, you know, there's no conspiracy to like hide research on, you know, from the early 1900s on people who were doing high fat diets. Because first of all, part of it was to elucidate the mechanisms of metabolism itself, which, you know, like beta-oxidation wasn't really a thing until 1910s or 20s. Anyway, it was early. So, but then, you know, we didn't have a full picture of metabolism until like, you know, until the Krebs cycle was discovered decades later. But, you know, we got pieces along the way. But anyway, so back to keto, one of the other cool things that they, I legitimately do think is really cool, they show, you know, keto adapted athletes versus non-keto fat oxidation rates. And they're well past a gram a minute, which is huge. You know, we're looking at 1.4 to like... 1.8 or 1.9 grams per minute. And imagine if you did one point, like, let's call it two grams a minute for an hour, you know, that's 120 grams. What is that in pounds? Is that like a quarter pound? Yeah, 120 grams. So an ounce is like 28 grams. Yeah, that's a quarter pound. Oh my God, my back of the napkin mouth was right the first time. Mark this occasion, that's a first for the podcast. First and only. And only, we'll make sure of that. Yeah, and so also like a couple of the statements that they made, I was unimpressed with reading these papers, like not providing any references, like certain behaviors of blood glucose. And I'm like, I want to see a study that shows this. Behavior of Blood Glucose. Don't reference one. I could probably go look one up, but I couldn't find one. So maybe that's on me. And also anecdotal and subjective evidence that gets called empiric observations, which offended me personally, given what I've named my coaching company. Yeah, I think it was always a little bit suspect when These claims for this diet are coming from someone who's trying to sell you a training plan or a nutrition plan or meal planning services or what have you. Obviously, they want to sell you a product, so they're not going to hand you a cut sheet that's just got a bunch of hard-to-read tables and weird graphs from papers that they don't probably understand. Of course, they're going to throw in really, really impressive-sounding language. That doesn't surprise me. It worked. It worked on a lot of people. And that's how marketing works. Yeah, for sure. Okay, so I think the last thing that a lot of these papers show with real promise is the kcal per hour or kilojoules per minute. The other thing that I think is weird about these calculations is that they're not familiar calculations. These could be completely turned into power, but they're not. They're expressed as kcal per hour or kilojoule per minute or grams of fat per minute. And it's like, oh, that's cool. That's a lot. Is that a lot? How much is that? How much do I normally do? Like, we don't have a sort of everyday reference value for any of these kinds of things. you know a normal value that most people would think about that you know at least for cyclists you know I'm sure they weren't thinking about cyclists so much when they wrote these papers but you know for us you know it would be very helpful and to just think about power output right? Yeah and I think a lot of even recreational athletes or even even when you get into like running or another endurance sport that doesn't have power meters thinking about things in terms of power output is not so familiar to them either. So... Yeah, I would want to see something for running in velocity. Like, that would be doable as well. Yeah. On one hand, it could be... The advertisers being a little bit disingenuous and picking these numbers that you don't have a strong reference for, so it's hard to determine whether this number is good, absolutely, and they only present it to you in a comparison. And on the other hand, it may just be because they lifted something straight out of some paper and they themselves don't really understand whether this number is good or bad, absolutely, but it sounds good because it's compared to a number that's smaller and bigger is always... Better. Yeah. Well, and, you know, I think also when you see numbers like this in journals, like they have a legitimate purpose to be there, except, you know, except when it comes time to, you know, translate it to the average person, I would say it's hidden by the veil of dimensional analysis. Like there's a good amount of unit conversion that has to go on and... It's been a long time since I was in chem class and I had to do unit conversions like that. And I'm not that good at it anymore, frankly, to the surprise of nobody. Anyway, so let's talk about one of the greatest hits from the recent decade, the 2010s, which is Louise Burke's study on elite racewalkers, which I'm sure a lot of people have probably heard of in some degree or other. But it is one of the really good experiments and an elegant experiment that shows kind of what we're dealing with when we get into the keto diet. So before Burke's study, studies had really only been done in athletes who perform at a low level or low intensities like triathletes and ultra runners. Ultra Runners, for instance, I might say that that would be an ultra whatever, would be an instance, maybe not a, depending on the race, maybe not the best idea, but sometimes it can be a good instance of like, oh, I need to fuel less or I want to fuel less, keto might be a good choice. I think we've said that before on the podcast. But one of the things that's happened before, or one of the things that happened in this study is they only controlled the diet. Otherwise, the athlete's trained as normal. And so, wait, Kyle, have you ever seen race walking? You have, right? Yes. Yeah, of course. It's... Does it look strange to you? It looks strange to you. It looks like they're trying to run, but they're wearing really heavy shoes. Oh, yeah. I mean, it's because they get what? They get like two or three... I forget. They get some number of... instances where a judge can call them for having both feet off the ground and if they exceed that number they get disqualified because that's running and walking definitionally has one foot on the ground all the time and the thing that defines running is that for brief periods of time right like both feet are off the ground and so yeah they have to like swing their hips and legs as rapidly as possible and impart as much force on the ground as they can, but not so much that the other foot loses contact with the ground. Yeah. Actually, you know what it reminds me of? Did you ever see those videos of those weird cult people, the functional pattern? Yeah. When they're running and they've got that back-on view of somebody on a treadmill and the before. You see somebody running and their hips are moving a little bit. And then in the after, their hips are perfectly stable and everything else is going around like matte. It looks so weird. It looks a little bit like that. But race walkers are actually badass. Like their times over like 10K, 20K, a lot of people would be really lucky to run that. Oh, totally. Yeah. No, the times that they do are really impressive. Pete, you know, okay, if you go out and walk a mile rapidly, right, like, you can probably get down below 15 minutes, right? Yeah. But these people are out there doing, doing like, yeah, basically what you would, you'd, you would do is like a gentle jog for a mile walking and they're able to do it at marathon or longer distances. Yeah. And so that's one of the cool things about the study. So these are like serious, real athletes. and they're in the study of really high level athletes. So 22 of the 29 participants from this study year either went to the 2016 Olympics or the race walking team championships, which were the two biggest races of the year for race walking. Oh my God, sorry. Oh, you're right. Just to look it up, the men's world record race walk mile is 536. Oh my God. 

What? Like a sub six-minute mile walking. All right. I am duly impressed. Okay. So that's the caliber of athlete that we're dealing with here. Yeah. Okay. So besides the people who went to those two races, they were their training partners, for instance. So a bunch of really, really, really high-level people in this study. That's a big feather in its cap here. So the study design does three weeks of isoenergetic diets, meaning they all have the same kcal or kilojoules, which will be important, make note of this. So the first diet is high carb obligately, 65% of all calories come from carbohydrates. Diet two is periodized high carb and low carb availability. Following the periodized train low ideas like sleep low, don't carb feed after exercise, start some sessions with low muscle glycogen, stuff like that. We've got the paper linked in the show notes. So there's a complicated table if you want to look at exactly how the diet was done. So that'd be table two. So check there for details. Diet three is just low carb. It's about 80% fat of all their calories. Less than 50 grams per day of carbohydrates, which makes me sad just reading it. That's like none, right? Yeah, it's enough to make up for what you get in meat. Yeah, it's like a banana is like 30 grams of carbs. Yeah, depending on the size of the banana, but yeah. Yeah, like you're talking, I mean, ballpark, you know, a banana is like... just over 100 calories or whatever. So you're talking like maybe a banana in half a day total. And that's if you were intentionally eating it, right? So you can't have spinach or celery or even the really, really liquidy, watery vegetables. You can't have very many of them. Yeah. So the participants for the study were educated about their diets, which is also another big feather in the cap for the study. And so they did this to control for the placebo effect. And so they allocated people to their preferred group or they did not put people in a group that they did not want to be placed in. So if somebody didn't want to do the keto or the periodized carb thing, they just were put in the high carb thing. Or if somebody was like, oh yeah, I want to do keto or I want to do periodized, like they got put there. So between either... Somebody's preference or somebody's preference to not be in a group, they were actually able to get three really well-matched study groups in terms of age, VO2 max, personal best 10K and 20K race times and things like that. So this was a very, very good study design. The diet intervention occurs over a three-week camp before their events or some events. This was not like right before the Olympics, by the way. So as some of the participants, according to the paper, did two camps in dietary interventions, but we may get into that later. The training programs were mostly the same in that everybody who participated had the same six required sessions per week, including strength and cross-training, and otherwise it was up to participant preference. So these were pretty serious camps. And before and after the training camps, they tested VO2 peak. Not Max, important to note this, VO2 Peak, and Economy. So Economy is something we don't talk about in cycling very much because it doesn't have the biggest impact on us because we can't really change our technique that much. Like our fit probably has a bigger impact on economy, which is going to be very small relative to like changing your running stride. So Economy is O2 consumption versus your moving speed done sub-maximally. So this is not sprinting. So economy is like considered, you know, your endurance pace or your marathon pace or something like that. And usually we think about it for running, but in this case, it's for race walking. And so they tested all this during a graded exercise test with a couple steps. And the first couple steps were sub-max and they got to test economy. After the, well, before and after the training camp, everybody did a sanctioned 10-kilometer race. And so pre-intervention, everybody ate what they normally would. Post-intervention race was eaten in accordance to their diet restrictions. So this is going to be important later also. So day three of the testing phase. Also, so day one was the lab test, day two is the race, day three is a 25-kilometer walk, alternating every 5K outdoors and indoors, and the indoors was in a lab to get metabolic data. So this was done at one of the Submax economy tests, or about their 50-kilometer race pace. So if your 20-kilometer personal best is a little over 80 minutes, which it is average for all the groups, So the 50K is going to be in the about three-hour range for endurance. Which is 50 kilometers is just over 30 miles, right? So imagine how long it would take you to walk 30 miles versus these people who are like, yeah, that's less than four hours. Yeah, how long does it take you to like an average person to run a marathon, like four to five hours, something like that? Yeah. And these people are walking longer than a marathon in less time. Yeah. All right. So now we get to, so what happened with these athletes? So if we look at, this is going to be table four in the paper. Paper, by the way, is open source. So you can just go read it. So click on the link, check it out if you want. In figure four, what we're looking at is their race times from the pre-camp race to the post-camp race. The keto groups' times stay the same. The carb groups, both of them, got faster by about two to three minutes on average. And this is a statistically significant difference, and there was no difference found in the keto group. All right, so during their post-test race, the VO2 for the carb groups did not go up. at 20K pace. But the O2 use as a percentage of their VO2 peak went down. Right? Does that make sense? Right. The actual amount of oxygen they were using went, like, it could have... stayed the same from before and after, but because their VO2 peak is now higher, they are working at a lower percentage of maximum. Right, exactly. And so in the keto group, they're actually working at a higher percentage of their maximum to go the same pace they did before the camp. Right, whereas the high-carb group is actually going faster. Yeah, and so what's another way of saying this? And Burke puts it in the paper, quote, low-carb, high-fat, also increased the O2 cost of race walking at velocities relevant to real life performance, unquote. And so what's another way of saying this? Their economy for keto was reduced, which means you've got to use more O2 to go the same speed. And compared to the carb groups, you know, they're using less of their VO2 peak in the race, and they're going faster. Yeah, seems like a win-win. I don't know. Work at a lower intensity and go faster? Who doesn't want that? Yeah. Yeah. And so like for the keto group, both variables, the speed and the O2 consumption went the wrong way to save the economy calculation. Yeah. Yeah. In fact, the title of this paper has it right in the name, Low-Fat, High-Carb Diet Impairs Exercise Economy and Negates Performance Benefit from Intensified Training. There you go. Seems like a pretty conclusive title. And even if you just read the abstract, it seems like it's fairly conclusive. There's no gray area here where you could weasel out some maybe pro-keto diet for race walker support. Yeah, exactly. So it's unfortunate, but there is a criticism of this study that we're going to get to in just a minute. But first, I want to think about... Why did the keto group's economy get reduced? So I put down my thought before I even read the discussion. So I went straight to motor units as people probably expected. So the low glycogen from the high-fat diet increased motor unit recruitment at race intensities. So less efficient muscle fibers were potentially used and referred to the slow component episode of the Wattstock series. My other thought here, I would say to a lesser degree, is potentially less ATP is produced by fat since because fat breaks down into equal FADH and NADH contributions as opposed to more NADH via carbohydrates and refer to Wattstocks number 29 and 31 for that. I think those were those episodes. We can see this actually in a RER table with carbs versus fats. So with the non-protein combustion, At 100% carbohydrate combustion, RER of 1.0, we get 5.047 kcal of energy out per liter of O2. Okay? For 100% fat combustion at RER .707, we get 4.86 kcal. Per liter of oxygen, yeah. Per liter of O2 used. Yeah. This right here points toward what we said earlier about the Keto Group having to work at a higher percentage of their VO2 peak because they're going to need, you know, call it 16% more oxygen to get the same amount of energy out. This is actually supposed to be one of the benefits, by the way, because remember, per gram of fat, we get 9 kcal. Right, yeah. Yeah, so remember the classic thing is like fat is more dense energy storage, right? Because we can store a lot of energy in fat and because per gram of fat we get 9 kcal, whereas for carbohydrates and protein we only get 4 kcal per gram. Right. But the energy density per storage unit is not the same as what can we get out per liter of O2. So it's an important distinction. Right, yeah. So you're adding in this other, if you were just straight up burning fat by mass or carbs by mass in a controlled environment where you had unlimited oxygen and your only rate limiter was either the amount of fat or the amount of carbs you have and it was limited by weight, the fat would definitely win. But you are, because you're, I don't know, not Just adsorbing oxygen through your body into your blood. Your body is not in a controlled environment where oxygen is more than plentiful. You are actually in a somewhat oxygen-limited environment. So that's why, going back to your Oreos and thinking about that earlier, this is why... Just thinking about something like how many calories do you get out in like the bomb calorimeter experiments is not 100% conclusive when you apply it to how does your body actually use these things. Yeah. Yeah, that's very true. All right. And so what was Louise Burke's opinion? Why was the keto diet group's economy impaired? So she's actually in the camp of the ladder where she thinks that, you know, because the... Fat combustion per liter of O2 is higher, so to meet their energy demands, you need more O2, which can get you working at a higher fractional utilization of your VO2 max. So she notes smartly, and I quote, when exercise is undertaken at a modest fractional utilization of an athlete's aerobic capacity, There is opportunity to compensate for a loss of economy by increasing oxygen uptake. However, during activities conducted at or around an individual's lactate threshold, such compensation is not possible and reduced ATP production from the available oxygen supply will limit exercise capacity. Burke, by the way, also notes that other researchers have also found an increase as expected in the fat mobilization and transport mechanisms like HSL, Fat-slash-CD36, Intramuscular Triglycerides, and CPT, which was, CPT was discussed in the last episode, by the way. And we mentioned previously that having more of these transport mechanisms, this is a way to actually burn more fat. And, you know, see, we were right about this. But we'll eventually get to how one might do it without resorting to keto diets. Probably not this episode, but I think it should be. Pretty obvious by this point. The last point to make about the study here is that for the keto athletes, there was a concomitant decrease in carbohydrate use as well because it makes sense that you don't burn what you don't have, but also this means that their liver wasn't keeping up with the gluconeogenesis requirements that the body would have to burn glucose at a normal athletic rate, same as the high carb. People. Does that make sense? Yeah. Yeah, yeah. I mean, geez, I can't imagine. I mean, I can't imagine going out on one of these and that you'd feel well, but maybe these people did feel good. I don't know. Yeah. Oh, maybe they did. I don't know. I don't think they did. But the study also looked at blood glucose levels. And they didn't tank. They actually maintained. This actually proves a point that the body needs glucose. Glucose is required and the breakdown of glucose pathway is required because there's a lot of things that are necessary to, I don't know, what's it called, be alive? That come off the glucose metabolic pathways and so the liver will be like, oh God, we need some glucose, we'll make this. This gets into something I saw in someone who was promoting the keto diet as being not just good for athletes, but good for health generally for all people. One of the things this person was saying was that because your body can go through gluconeogenesis, that carbohydrates were not an essential food. And using the definition of essential, like the way that essential amino acids, like that is used in the phrase essential amino acids, where certain amino acids your body cannot make, this person was arguing, well, your body can make carbs, therefore, it's not essential that you eat them. Yeah, but that's kind of doublespeak, isn't it? Because scientifically, that's true. Oh, totally, yeah. I was like, wait, wait, wait, wait. But most people are like, oh, so we don't need to eat carbs, they're not essential. It's like, these are two different definitions that we're using here. Oh, totally, yeah. I was like, that is a complete abuse of the term essential in this context because your body makes these things because they are needed and this one specialized definition of essential amino acids is not broadly applicable to all compounds that your body, oh, you know, your body can make a lot of things but it does so exactly because it needs them. Yeah. Yeah. And so, okay, so to wrap up this little bit about this Burke paper, in the last paragraph or one of the last paragraphs of her paper, she actually calls it an unsuitable practice and cautions against likely lower carb absorption rates in the gut and whatnot. So did she speak too soon? Because the main criticisms, I think, of the study were actually fair. So what were they? So low-carb, high-fat adaptation should be followed with carbohydrate supplementation to reap the benefits of fat adaptations because of the fat adaptations that are going to persist, plus then you get enough time to readapt to having carbs again. So does this sound like a promising criticism for the study? Because they didn't get any chance to readapt to carbs, right? I think so, but I think in a lot of places that I have seen, where they advertise keto being good for athletes. Like you mentioned earlier, they sort of pitch it as this, you are unshackled from the chains of having to eat carbohydrates. And they, maybe not, maybe they do in the plans. I've never actually purchased one, but at first pass, it does not appear that they say, oh yeah, and then by the way, before competition, you should eat carbs again. Yeah. Well, I think also, A lot of it's for more explosive type efforts. And I think there's a misunderstanding about the metabolism that happens because like we talked about in what was that, episode two or three or something like that, the training too hard for cartariums thing, that was talking about the creatine phosphate regeneration being aerobic, which it is. But one of the things that I didn't get into because it makes it way too complicated is that when you are doing these super hard efforts, there's not enough creatine phosphate to supply this stuff. Yeah, for sure. Even in a five-second sprint, you're going to use a ton of carbohydrates. And if you're lifting weights or if you're doing Olympic weightlifting, you're going to use a ton of carbohydrates. Especially because your brain has to be so turned on. Like you have to be so mentally focused for one rep max sports, right? Like if you're in kind of low carb, low glucose, like fog. Yeah. Well, that's kind of one of the things that we talked about in the recent 10 Minute Tips episodes on lifting too. Yeah. All right. So Burke, one of my favorite scientists, by the way, forgive me for fanboying out here. So she does a follow-up study. The title of her follow-up paper starts with Crisis Averted. So we can see where this went. So they did a very similar design. They included women this time. And, you know, because in the previous paper, it looked bad since the 10K after the low-carb camp was really rough on those participants. So once again, in this paper, the 10K race after the camp was again rough on these participants. But then everybody did about two weeks of carbohydrate reintroduction. which included a race taper and then they did a 20K. And so what happened was the keto group bounced back to similar levels of performance as the group that never went low carb but did not make any improvements beyond coming back up to the level at which the other groups had all been trained up to. So the camp still had an effect but going low carb for it didn't have any performance benefits. Interesting. So that seems like one of these things where that to do, this is for me, to do this extra intervention and to like radically change what you're eating just to get back to where you were doesn't seem particularly appealing, but yeah, that's my opinion. Yeah, not really. So what's our bottom line for exercise having gone through this study? I think it's that based on what we've discussed in previous few episodes about metabolism, what we're seeing is that the muscles in the body and the body itself also have a good deal of plasticity to them because evolution has seen fit to give the ability to be flexible with our fuel choices, but that does not also mean that exercise capacity is all created equal. We can only still deliver a certain number of liters of O2 to the muscles per minute maximally or at threshold. And so rapid and long, hard ATP demand power outputs, like a 60-second max effort, for instance, or maybe a 10K race walk, you need carbohydrates to meet that rate of demand. Increasing submaximal fat oxidation by diet manipulation is cool. It's good that we can do it in terms of evolution and food resources and whatnot, hunter-gatherers and all that kind of stuff. But for pretty much anyone but ultra-distance athletes, you will probably require tons of carbohydrates for your event. And even then, there are successful ultra-marathoners who eat tons of carbs, like Courtney DeWalter, again, fanboy. So she's great, and she is up there with the fastest men even. No, and I think this goes to say that But like with a lot of things, when you talk about training, when people say, oh, what's the best training to do? That's kind of like asking, what's the best diet? Like, there's only going to be one best diet, and the rest of them are all suboptimal, and there's just going to be one, and if you do this sport, you know, no one would ever say, oh, if you do this sport, there's this one best workout, and you should only do that one, because all the rest of them aren't as good. Yeah. Well, I think we should also say, like, make that asterisk like the best diet for your performance. Because if it's like, oh, this diet's got 65% carbs and this diet's got 70% carbs, it's like eat what you need. I think one of the things that I was looking for in the study before I read it was that I was looking for better time to exhaustion. How long can you maintain a submaximal pace because you don't have as many carbohydrates to rely on, but it turns out what carbohydrates that you are relying on are in fact being used. And so there was a study, we'll link it in the show notes, done by Finney, which was actually 1983. So it was a really early one. The average TTE, so time to exhaustion, is similar between the keto group and the non-keto group, both before and after being keto adapted. And it's not short either. It's like 147 versus 151 minutes. But the RER table is interesting as well. But basically it showed that low-carb, high-fat diets don't really improve even the endurance aspect of exercise performance for like a sub-max effort, like a three-hour effort or something like that. Really, I think the only promise it has is really with ultra if feeding is a really big issue. So like what... Other lessons can we take away from this? Because, you know, we've been kind of talking about the strict measurement of performance aspects here. So, again, what limits exercise performance is beyond the carbohydrate fat decision. And I think looking at the last couple of Wattstock episodes, we kind of started to show that. But especially for bike racers, the over-threshold stuff will definitely suffer. Wattstock number 10, we went into that. But, you know, in the first Burke paper we looked at, she notes that media will typically look at things like stage races, triathlon, marathons, and such as submaximal events when she, again, very smartly notes that tactical situations can often be decided by short efforts that are well over threshold. and would require large amounts of carbohydrates. So even quote unquote submaximal efforts can actually be quite high. Yeah, that makes sense. And I think that's maybe the problem when you look at a sport and you don't have a super thorough understanding of how races and competition actually unfold. Like if you look at a data file from, I don't know. Andre Greipel like going having a jaunt at Flanders and you just look at his average power versus his FTP you'll see oh like he was at some you know moderately moderate percentage of his FTP on average for the race and if you're just like oh that's a race it just must be just a long tempo ride yeah right like oh no it is not it is not just a six hour tempo ride like Literally all of the hard parts are way above threshold. Yeah, they are very, very hard. And so I think we can kind of close out this episode with another quote by the inimitable Louise Burke. Quote, it should enhance an athlete's capacity to utilize... and integrate all of the body's range of energy producing pathways with special focus on ways in which they become specifically limiting for performance. That quote, it makes me laugh, right? Because I don't think it's any secret that one of the sports that has kind of embraced keto the most is CrossFit. And they like to sell people on the idea of CrossFit. I totally understand the appeal of this that their sport is highly varied and as a human it's it's it's not ideal to just specialize in one thing and they're gonna do all of these different movements and combine all of these different sports and activities into one and you're like okay that that fine that sounds interesting but then to then go on and say that Keto is the best because it lets you burn fat really, really well. Aren't you then locking yourself into this? You're committing the same, quote, error of specialization that you rail against in sports and sports performance in diet and exercise fuel. Pathways, right? Yeah, potentially. I mean, I don't even know how prevalent it is in CrossFit anymore. I'm sure all my CrossFit friends are going to, you know, one of them actually will send me screenshots or she'll send me pictures like, hey, look what's on the CrossFit gym this morning. And it's like this podcast, like, hi, everybody in CrossFit. Yeah, you can flame me all you want. Thanks for listening, yeah. All right, let's wrap this up real quick. All right, so. Thanks everybody for listening. Again, share the podcast if you thought it was pretty good or like what we're doing here. Tune in for the 10-minute tips episodes as well. If you're a nerd, you'll get a lot of very practical conversational type chatter there. So that's good stuff. Share that. Remember, we're ad-free. So empiricalcycling.com slash donate is where to send us a couple bucks if you would be so kind. Five-star iTunes rating would be great as well. We've got the show notes up on the website, empiricalcycling.com as you expected. and if you want coaching, inquiry, consultation on to training or weightlifting or whatever it is send me an email empiricalcycling at gmail.com if you have any questions or comments let me know there or you can send me a DM or follow me on Instagram at empiricalcycling we've got the weekend AMAs the Instagram stories so I'll see you over there and with that see you all next time thanks everyone