Welcome to the Empirical Cycling Podcast. I'm your host, Kolie Moore, joined by my co-host, Kyle Helson. I want to thank everyone for listening, and I just want to remind everybody to please subscribe if you have not yet, and that we are an ad-free model, so please go to empiricalcycling.com slash donate to donate to the show. We've got our show notes on the website. We've got a bunch of links to all the studies that we're talking about here today. And for any coaching consultation inquiries or questions or comments about the show, please, or possibly hate mail for today's topic, Please send an email to empiricalcycling at gmail.com So why could we possibly get hate mail for this, Kyle? Well, today we're going to be talking about something that I think you and I kind of make jokes about back and forth, but the recent rise in popularity of keto or ketogenic or low-carb diets for athletes, and in particular, you know, every athlete I think is looking for some Advantage or some way that they can be a better athlete and either race better or perform better or something like that. And so this has really become a popular topic of discussion and a very sort of trendy, if there can be such a thing, a trendy thing in the past four or five years. Right. And so that brings us to the question that we are going to answer today on the podcast, which is, can a fat-rich diet lead to better endurance performance by sparing glycogen? And this is one of the proposed benefits of becoming fat-adapted. So just so we're clear, we're going to be saying fat-adapted or fat-adaptive diets. today in order to, you know, kind of encompass the whole gamut of them. But we know that there are really big differences. So if you really think this one instead of the other, that's okay. We understand the differences, but we're lumping them all together for today's purpose. And by the end of the show, you will understand why, you know, that might, it makes sense to do that. Also, I want to issue a warning that if you trust our judgment on this, please listen until the end of the episode before you make any decisions for yourself because like in all things, there are benefits and drawbacks and as in all the episodes we've had so far, regardless of how I use anything in my coaching methods, I just want to present Everything with kind of an even-handed approach. So I think if you look back probably, you know, a few decades, you can kind of see different trends and different popular diets or dietary advice in sports and performance. And then somewhere along in the late 90s, early 2000s, low-carb, sort of high-fat diets have become really popular for both weight loss and then also people looking at them in terms of performance. The idea that people often have is that if you're going to do a very aerobic sport like cycling or running that because it's aerobic you must be using mostly fat and therefore eating high fat diets must be better and people also think that oh carbs your body has a much more limited supply of glycogen and carbs, but much more fat, right? You have somewhere, most people listening here probably have somewhere between 10 and 25% body fat in terms of their weight, whereas you only carry sort of, you know, a couple thousand calories worth of... Glycogen maximally in your body at all times. So thinking, oh, if I become really fat adapted and don't eat any carbs and eat only fat and protein and force my body to become really good at using fat, that must make me better at sports. By mechanisms that propose that we're going to go through today, some of which, not all of them, but we're going to go through a lot. The main question that we're going to get to, does this mean that what glycogen you have, you can spare it and use it when you really need it? Or also, you know, I see a lot of, you know, reducing your quote-unquote dependence on carbohydrates touted as a big benefit also. Yeah, I think that's one of those ones that's kind of, I've always thought was kind of confusing because your quote-unquote dependence on carbohydrates, like, yeah, there's something to be said for being really efficient and a really good, really good at using fat, but like, You're not going to somehow change the metabolic pathways to magically not use glycogen just because you ate a lot of steak and cheese and bacon or something the night before your race. Right. And that's because... That's because no matter how fat adapted you are, you are going to be using carbohydrates because substrate use changes based on not only your diet, but also exercise intensity. And you're never going to do like a 30 second all out sprint and have it be 98% fat. That's just not going to happen because, you know, we'll get into this deeply in another episode, but just real quickly, it's because the mechanism by which we get ATP from fat is very slow, and getting energy and ATP from carbohydrates is extremely rapid. And I think that's something we've talked a little bit about before when we were talking about different metabolic pathways is that the reason that your body starts covering efforts initially, regardless of the total intensity, but the reason that your body starts covering efforts initially aerobically, or not aerobically, is because it's slow. Because aerobic is slow, exactly. Yeah, because aerobic is slow. Before we really dive into this, I want to issue a couple words of caution about some of the studies which are out there on fat-adaptive diets for athletes. In my opinion, a lot of them read a lot like marketing materials more than actual scientific studies, written a lot by keto proponents and manufacturers of exogenous ketone and similar products. Just, if you're wondering, save your money. They're really expensive and they're not worth a tenth of what they're getting sold for. And you could probably just drink nail polish remover for the same effect. I don't suggest drinking nail polish remover. No, please don't do that. Just real quick on a lot of the studies that you're going to see, because there are a lot that really don't pass muster for really good scientific papers, although they do get published, which we'll probably get into another time, does not necessarily equate with scientific worth. There's a lot of phrases that I see in these papers to support certain points that Don't Get a Reference. It's just assumed that it's known, for example, from one of the worst offenders that I saw. Quote, another reported benefit of performing high-volume training in the keto-adapted state may be reduced, delayed onset muscle soreness and accelerated post-exercise recovery, whereas it is common to take many weeks off from training after a 100-mile running event. Keto-adapted athletes report that they can resume training and even competition within a week or two, unquote. Kyle, how does that sound as empirical evidence? He calls it, by the way, quote, empiric evidence, unquote. As somebody who named his business Empirical Cycling, I'm actually offended by this. It's basically the definition of anecdotal evidence. Like, oh, my buddy said he tried out this. you know disgusting nail polish remover drink and he got a fifth in his you know you know annual crit that he that he targets so therefore it must be good right yeah yeah we all want to do everything the fast people are doing okay and then there's the other type of study out there obviously it's not all of them but quite a lot I saw had this problem where they did comparisons between test groups That first, bear no relation to the real world, and second, didn't control for caloric intake among the test groups. So I saw one that had two fasted groups of people doing endurance cycling to exhaustion. One had no food, and one had fat-based food. And Kyle, what do you think happened? I'm going to guess, wild guess here, that the people who ate something, anything, anything more caloric than air, Probably did better. You are exactly right. So I saw another with a similar setup that gave carbohydrates to the carbohydrate group. Go figure. They gave them 40 grams of carbohydrates for breakfast and then nothing else before a long, hard test. And so if you're not fat adapted... We'll get into this in a little bit. You need to keep eating carbohydrates. So this bears no relation to the real world. So if you are used to eating carbohydrates and then suddenly you're not eating carbohydrates, you only get like 40 grams, that's like two gels worth before several hours of exercise or something like that, you're not going to perform that well. I say all of this as someone who understands that there is utility to fat-adapted diets, and we're going to get to those for sure. Just some of these studies don't really pass muster. I think it should be, it's kind of worth noting here too that it's not just the low-fat, or not low-fat, the low-carb, high-fat studies that... Have a lot of these problems. Like, the original study that, like, Gatorade likes to talk about how, oh, athletes who, like, drank Gatorade versus water, like, had a longer time to exhaustion. Well, duh. It's just the exact same thing we just talked about. Like, the people who drank Gatorade were drinking sugar and water and salt. The people who were drinking just water, they didn't have any calories. And then back in the, like, I think the mid-2000s, the company started, this one company started releasing an intra-workout drink that had sugar and a little bit of protein. And they would say, oh, in the studies, these people who drank this drink with a little bit of protein have longer time to exhaustion or whatever than people who just drank just carbs. And I was like, well, that's because if you add a little bit of protein per serving, you're increasing the number of total calories per serving. I actually remember seeing a study where people went back and they controlled it for a total number of calories versus the carb only versus carb plus protein, and that time to exhaustion was the same. Right, but that's not a very sexy headline, is it? It's true, yeah. Our drink is exactly the same as those other drinks, damn it, damn it. Okay, so in order to start getting into how we can think about fat and carbohydrates and what we use and when and why during exercise, let's think about what happens in a muscle going from rest to exercise. At rest, there's low ATP demand, but generally we know that carbs are being used somewhere in the body because there's always a low level of lactate in the blood, like 0.5 to 1 millimole, something like that. So if you want specifics on that, look at Watts Dock number 6. And, you know, the lactate dehydrogenase enzyme is always active in case we suddenly need to use carbs and we can't really switch it off and it's in equilibrium with pyruvate. So, therefore, you know, we always have a little lactate in the blood. Not a big deal. When we start to exercise at any intensity, the body is slow and it's conservative. It's like trying to get a teenager out of bed, right? It's like trying to get me out of bed, let's be honest. how long the exercise is going to go on for and therefore how long ATP demands will be higher than the demands of rest. And so ATP demands over resting levels are first covered by phosphocreatine because it's easily renewable as discussed in Wattstock number two. And then the glucose and glycogen takes over because it provides an immediate source of ATP and it you know it lasts for a lot longer than phosphocreatine does after that depending on the exercise intensity so we're only at like you know 30 seconds right now something like that you know going from like say active recovery to FTP something like that depending on the intensity you're either going to just use glucose which would be something like you know the last 10 to 15 seconds of a 30 second hill sprint Or you will use a combination of glucose and fat like doing like a zone three or a tempo ride. And we're going to get into that another time. The crucial learning here is that this happens every single time we go from rest to exercise. So every single time in a race where you have to follow a surge or like you go from coasting to smashing up a hill, something like that. Process plays out based on the fuel you have available and the biochemical pathways that your body is ready to use and also fiber type and a million other things and we're going to get into what determines this kind of thing in another episode but for now let's just focus on the substrates. Let's think about how substrates are used aerobically because both fat and carbohydrates are used aerobically. They get converted to acetyl-CoA, and acetyl-CoA is shuttled to the Krebs cycle. The Krebs cycle creates reducing agents that carry protons and electrons to the electron transport chain. And it's the electron transport chain that is the true aerobic piece of machinery in our metabolism. And so this means that both fats and carbohydrates can be used aerobically because we're producing NADH and FADH2 through through both carbohydrates and fats. Does this kind of make sense? Yeah. Basically, your body isn't dumb. Like you said, it's going to use what is available. Humans have evolved over the last thousands of years to be fairly flexible. We're omnivores. Probably one of the reasons why humans have been so successful in surviving and not dying out is that Our bodies are very adaptable and we are very flexible and this is just one more example of that. The body shifts its aerobic metabolism based on what it has available and training. So let's look at substrate availability. So if you eat a lot of carbs, your body uses more carbs. If you eat not as many carbs, your body switches over. to fat preference for aerobic metabolism. And that's just a preference. So in a lot of studies where people are keto-adapted and they have astoundingly high rates of fat oxidation, the drawback is that you have very low glycogen stores no matter what the marketing materials say. So from a pro-fat-adaptive diet paper, Here are some numbers. So they have a carbohydrate group and a fat-adapted group. And the carbohydrate group has 143 millimoles per kilo of glycogen before exercise. And the fat-adapted group had 76 millimoles before exercise. So they have half the stores. Now, after exercise, the Carb Group got down to 56 millimoles per kilogram of glycogen and the fat adapted group got down to 53. So they got down to the same level. Your body probably stops you at some point before you're absolutely down to zero because then, you know, it's probably very bad for your muscles and for your cells to live. But the group that had lower glycogen stores to start meant that they had less fuel available to burn during that exercise. Right, but they actually used a lot of, they actually used a very large amount of fat as fuel. However, this exercise was pretty submaximal. you know doing submaximal exercise need to remind you about these numbers that say that even the fat adapted group doing submaximal intensity exercise still used about 20 some odd grams of glycogen per kilogram of body weight and so so like like let's say you're riding at like zone 2 or zone 3 pace like endurance or tempo-ish and you are very fat adapted you're going to use a lot more fat than somebody who's Pounding carbohydrates the whole time. And that's just because your body's just using what it's got available. You're going to say, or somebody's going to say, if you start out with more carbohydrates available and you end up with the same amount and you cover whatever you don't have with fat, this seems like it might be a good thing for bike racers, doesn't it, on the surface? However, we're going to get into some of the drawbacks of this and we're going to address the question that we asked at the outset very directly. So we're getting there. We're getting there. Okay, so if you're doing exercise that requires large amounts of ATP very quickly, you are required to burn carbs because you need it available quickly. Remember, burning fat is slow. So this strategy actually reduces your stored fuel for those high-intensity efforts. So lower-intensity efforts, Not a big deal. High intensity efforts starts to become a big deal. So the body is, you know, as we've said, it's very adaptable to use carbohydrates or fat or protein at rest. That's just at rest. So turning protein and fat into carbohydrates or its derivatives is slow in case, you know, you do, because we do have those processes. in our bodies that we can, you know, we can pretty much turn most chemicals into most other chemicals at some point. That's why you can turn alcohol into carbs. Exactly. Okay, so the body is very adaptable to use carbs, fat, and protein at rest, but during exercise we have different requirements. So we can actually turn protein, fat into Glucose, Carbohydrates, or the derivatives thereof, of carbohydrates. But it's slow, but it's not infinitely slow. So yes, if you eat a lot of protein or something like that, you are going to be able to maintain semi-normal levels of glycogen. We've got a severely fat-adapted group here at half of the glycogen stores, but it's not nothing. And so you've got some availability of glucose even if you are completely fat adapted. But while exercising at higher intensities, even at high intensity of daily life, like severe stress, the body uses and needs energy at a rate that is faster than can generally be supplied by just fat sources alone. or fat and protein. So training also affects the substrates that we use. So it shifts our preference from carbohydrates to fat or fat to carbohydrates. So a lot of training modes from high intensity training to VO2 max to threshold training to endurance in all of the scientific literature can and will improve your ability to rely on fat. and Spare Your Glycogen Stores. One of the points here that I want to make is that there are no short-term hacks to this. It takes years of consistent and high-quality training and we're going to get into some really cool studies that show this happening but it doesn't happen over the short term and we're going to get into a study in a minute showing exactly the kind of compromises that you're going to make. So you're saying that keto diets don't unlock secret metabolic pathways hidden deep within my physiology? Nope. Most of those metabolic pathways have been well documented by scientists by now. Oh, dang. So then this kind of meshes in with the experience I think that lots of people have when they start cycling is that if you're not well trained, Totally bonk and blow up and die farther away from the end of races than people who are well-trained. And it's not necessarily just that their FTP is higher, though it probably is also that their FTP is higher than yours. This kind of hints at it, that people who are well-trained, in addition to having very efficient aerobic production of power, that also translates into having that Little bit of extra glycogen at the end of races so they can out-sprint you up that 400-meter uphill sprint into the finish or whatever. Yeah, yeah, pretty much. And that's something that I really want to touch on. Actually, I don't want to touch on it. I want to go really, really deep into that in a future episode. But for now, I want to take a look at a really, really cool study. This is one of my very favorites on this topic. and we have a link up on the website empiricalcycling.com under the podcast episodes and this one is actually full text so you guys can go read it. It's kind of long but it's worth it. The study did exactly what we're talking about in terms of fat-adaptive diets. And then they did what a lot of people assume that you can do if they're on a long-term fat-adaptive diet. So on race day or like two or three days before race day, you start eating the carbs again in order to replenish your glycogen stores. So does this work is the question because this is one of the big benefits that's touted from these diets. Let's get into the study. So the participants underwent two eight-day protocols and they had a two-week washout period. And the two protocols were a seven-day low-carb fat adaptation and then one day of carb loading because, you know, we can't do a month. Sorry. Most people don't want to give up that much training time. And then a seven-day high-carb diet and then one day carb loading. So after the loading period, the fat adaptation groups showed significantly higher reliance on fat oxidation at submaximal intensities and had the same glycogen storage capacity. So even in a week, if you change the focus of your diet, you are going to very much shift your body's preference for fuel. Here's the test protocol. And this is one of the reasons that I love this study so much. They did a 100 kilometer time trial with alternating one kilometer sprints. They called them all sprints, even though it's hard to sprint for a kilometer fully. And four kilometer sprints. They did five one kilometer and four four kilometer sprints throughout the 100 kilometer time trial. So it's a really good mix of high intensity and low intensity. And so what are we going to see? if the fat-adaptive diet indeed spares glycogen for these performances because they're starting out with the same glycogen levels. So, Kyle, what do you expect? You would expect that the glycogen depletion rates for the people who were eating the carbs would be higher than those for the people who are fat-adapted if the theory that being fat-adapted helps you spare glycogen is true. Right. And so we should see better time trial performances for the one kilometer and four kilometer time trials. Yes. In theory, the times for the quote, well, like fat adapted athletes would be more similar at the end of the race, the beginning of the race than for the carb adapted athletes. Right. Okay. So here's what happened. For the entire 100-kilometer time trial, including all nine shorter efforts in it, there was no statistically significant difference between the eight-day trials for any athletes. But if we look at the individual results from this study, what we're actually going to see for the 100-kilometer time trial is that times went down, people went faster. between going from the high fat diet to the high carb diet. And there were actually three people whose times were pretty much the same and even went up just a little bit going from the fat to the carb diet. But most people's times actually went down a lot. So it didn't reach the threshold for statistical significance, but if we look at the individual results, we can actually see that some people, the high-fat diet may not affect them that much, but for a lot of people, the high-fat to the high-carb diet actually improved their performance a good deal. So remember, every athlete is their own control because they go through each protocol. What we did see was that there was a much greater rate of fat oxidation during the majority of the test that's not including the one in four kilometer time trials, it's just all the in-between endurance stuff. So you're going as hard as you can for your 100 kilometer thing and you've got to do all these sprints on top. So for that lower intensity, people are definitely using a lot more fat in the fat-adapted group. Now, one of the other things is that the perceived effort in the fat-adapted group for the 1 in 4 kilometer efforts was a lot higher. Now that seems like it could be bad. But if it's good for performance, then it's just one of those trade-offs. This is the data everybody's been waiting for. The power output for the high-fat group significantly lower in the 1 in 4 kilometer time trials. So in the 1 kilometer, The first and the last were pretty similar for time and power outputs for both protocols. But the middle three were significantly lower, showed a much larger reduction in power for the FAD-adapted group. And we can actually see that the FAD adapted group lost 70 watts on each of the middle one kilometer time trials despite having the same amount of glycogen as the carb loading trial. In the four kilometer time trial, all power outputs for the FAD adapted group were lower. And how much lower you want to know? Well, the FAD adapted group actually did about 40 or 50 watts less. average over the four kilometer time trials. So actually not that surprising because if we've got the five one kilometers, we can imagine them spread out and the four kilometers are in between those. So your very first and your very last effort being similar is not that surprising. But it's everything in the middle, which is four four kilometer time trials and three one kilometer time trials. that where you take a hit on your power output and your times significantly go up, you know, you're slower over these sections, that's the result that we, you know, that's bad, to put it very simply. Yeah. I mean, you can imagine this simulation does look a lot like road racing, right? Oh, it sounds like, oh, it's like a mini day out at Flanders or something. Yeah, exactly. Exactly. So you're saying in the middle there, I'm getting dropped a lot. Yes, you're probably, yeah, you're missing that like extra 50, 80 watts that, you know, for your, you know, for your five minute-ish efforts over the four kilometers, you know, that's going to help you make the selection or not. So the other thing that I thought was really interesting about this is that they also did an EMG. And so that's just a measure of electrical activity of the muscles. They just put little stickers on your muscle and they measure the electrical activity between them. So the EMG during the one kilometer time trials were similar. indicates a similar level of muscle recruitment. And if you want to know more on that, please see Wattstock number nine on the Size Principle. So the Size Principle, we're going to be talking about a lot here, so make sure you listen to number nine and just keep that in your head going forward. So author of the study thought that what was happening here was a greater amount of muscle recruitment in the fat-adaptant group, but after Listening to episode 9, you might disagree because I disagree. Though this is up for debate, you know, welcome to the edge of science. So what I think is happening here is that the same amount of muscle fibers were recruited and used because the EMG signal was the same, but resulting in lower power outputs. Now this means that there's a reduced ability to use carbohydrates as fuel, even if The glycogen stores are there. And this is in the high-intensity region where you're using basically all carbs, even though a large amount of them are being metabolized aerobically. On the other hand, if the author of this paper is correct, and a larger amount of muscle fibers is being used, then this is even worse because then your carb-burning ability took an even greater hit because now we have the same energy output from more muscle fibers, which means less energy output per muscle fiber. So this is one of my favorite studies on this entire topic, and that's why I'm really excited to share it with everyone, because this study looks very much like road racing. It really does. Imagine just sitting in a group and then having to climb a bunch of one-minute and five-minute hills. It sounds like a lot of road races that I know. And so if you think that you would be able to, you know, become fat adapted and then on race day, you know, get all your glycogen stores back and then, you know, have the best of both worlds, it really doesn't work like that. I would actually love it if it did. That would be really cool. But unfortunately, it just doesn't. To move a little bit away from cycling, you see this in other sports too where this exact strategy is touted of being able to like be really fat, high fat, high protein diets and then, oh, but right before competition, yeah, we're going to carb load again and it does sound appealing, right? It sounds like, oh, I'm like kind of getting my cake and eating it too or something but then, unfortunately, you run into this where... There is no such thing as a free lunch, I guess. You can't get that hack. God, I hate that phrase, but biohack's the worst. It's the worst. I hate it. I hate it. So I just have one more general thought on the effect of fats and carbohydrates, which is that pretty much since the mid-1900s, scientists have known that the ingestion of carbohydrates will reduce fat oxidation with immediate effect. and we're going to go way more into this in a future episode but it does happen for sure and so if you're wondering would that the fat adapting group have been able to burn more fat probably they would have had a higher fat oxidation if they hadn't carb loaded but they would have had even less glycogen stores for those one and four kilometer efforts so it likely would have gone even worse for them also there are more studies that in addition to this one that are actually more biochemically focused. So we're not going to delve into detail on those. But the point is that in addition to this study, there are others that show that a fat-adaptive diet actually reduces your ability to burn carbohydrates at a high intensity. So this is really like a low-intensity type of strategy, the fat-adaptive diets. And the short and long-term diets also probably have slightly different mechanisms by which you lose the ability to burn carbohydrates and get energy from that quickly. And it's probably a combination of gut microbiota changing and regulatory changes of key enzymes in the process of breaking down carbohydrates, stuff like that. So there are short and long-term versions of all that too. Does a fat-adaptive diet let you spare glycogen better for use at the crucial times in a bike race? The study really says no. It doesn't. But there are uses for low-carb and ketogenic diets. The first is weight loss, which is pretty obvious. If you train your body to burn more fat, then you can probably burn more of your own fat. And a lot of people have successfully used ketogenic diets in order to lose weight. And that's fine. However, we're actually going to get into the mechanisms of weight loss and such a little bit later. So for now, we're just going to leave it there. So the other thing that it's useful for is ultra endurance. Not just like a marathon, I mean ultra endurance. I mean you're looking at way more than an Ironman. Like because people do the 24-hour mountain bike races and stuff. Exactly, yeah. And you're looking at like 250-mile race in the desert, something like that. where, by the way, Courtney DeWalter is not fat adapted and she's kicking everybody's asses. That's a different episode. Yes, very different episode. Okay, so if you're doing very long races, like 24 to 72 hours straight, it might make sense for you to use the strategy, especially if you have problems carrying enough food and getting enough food to eat and It also requires that you maintain an even pace or a more or less even pace because remember like we were saying about how the body responds to sudden high demands of ATP. If you are suddenly sprinting up a short hill and you're halfway through your 36-hour race, you're not using fat for that kind of thing. You are definitely using carbohydrates if you're going hard enough. If you do this kind of thing a lot, then a high-fat diet doesn't make sense for that type of terrain. But if it's relatively flat and the rises are gradual and you can kind of like stay in your power output, then this is a very good strategy because you can eat less overall, you can carry less, you know, so it does make sense for ultra-endurance type stuff. But it actually wouldn't make a ton of sense then for your 24-hour mountain bike race. You might have a bad day. Yeah, you might have a bad day. And I coach ultra endurance mountain bikers and we actually do not use this strategy. So does training like this let you get faster? Now this could probably be an episode in itself, but I wanted to put it here because this is the next obvious question that I'm sure a lot of people have because this was the first thing that popped into my head, of course. You know, let's say you're an athlete who... wants to lose some weight, and before, you know, a couple long weekend rides, you're eating nothing but like eggs and some cheese and a salad or something like that. Like that's your pre-ride fuel. And you go out and train like that because you want to lose some weight and your body's burning a lot of the fat that it has, et cetera, et cetera, and you're losing some body fat and this is great. Does this make you faster? Does this make you a more aerobic athlete? Does this improve your efficiency? Et cetera, et cetera, et cetera. And I'm going to say no to this for two reasons. The first is that to train properly, bike racers need to do more than just train at low intensities. And carbohydrates become absolutely necessary when you train at higher intensities. And I'm even just talking about FTP training. Not even getting into like sprint work and stuff like that. So if you do one of these fat adaptation diets, there doesn't seem to be any structural change in the oxygen delivery or consumption. So you're still the same mediocre bike racer that you were before, but now with even less glycogen. Congratulations. And so here's the other thing is the body takes time to switch back to digesting and storing carbs. Properly. If your only carbs are what your liver can produce through gluconeogenesis, you don't need nearly as many carb processing enzymes, do you, right? So you don't just get right back to where you were. So in order to be a good bike racer, you need to be able to both have large glycogen stores and the ability to use them and be very, very efficient and fat-reliant as much as possible. to leave your large glycogen stores alone. So, in other words, you can't, you know, because we're talking about the trade-offs of one diet or the other, and we can use, you know, the diets, you know, as we see fit for the purposes that, you know, that they can provide us, but at the same time, like, in order to have it all, which we really want as bike racers, you know, Tour de France is going on right now, and, you know, this is like the, about 180-ish or something, like 180-ish of some of the best bike racers in the world who have the ability to do both, to be fat-reliant as much as possible and have large glycogen stores and use them when they need them. I mean, has anyone seen Peter Sagan, like, finish a race and eat, like, two handfuls of gummy bears, like, immediately after? He's not exactly going low carb on, like, 400 calories of Haribo. Alright, so with, you know, the wanting to have it all thing, there is actually a bottleneck in your physiology with aerobic energy supply. And whether you are burning carbohydrates or fats, you still only have the oxygen that your heart can deliver to your muscles and the constant ATP supply that you can get from your electron transport chain. There is no unlocking extra watts like this. We can change our substrate use based on all the things that we talked about, but you don't get any faster like this. Okay, so how do we actually get to these long-term adaptations that we want in order to become a Tour de France racer? The only answer is, and it's unfortunate, but it's long-term, very focused training and very focused recovery. In my experience, That is it. There are no silver bullets. There's no silver bullets. There's no hacks to find extra watts or whatever it is. The main determinant of long-term adaptation is the body's solution to best meet the demands for ATP at the rate, that's the shorthand for intensity, at which they are required. So if your diet... Doesn't matter what it is, does not allow you to complete the work required for adaptation, whether that's an endurance ride or FTP, VO2 max or high intensity intervals, then you need to change it. It doesn't matter where the energy comes from as long as you can do the work. So to be a good bike racer and to be able to ride at high intensity levels that absolutely require carbohydrates, you unfortunately need to keep eating carbohydrates. Unfortunately, man, I love eating carbohydrates. No, I think this brings up a good point that in terms of being a good bike racer, you want to be all around a well-trained athlete. Like you said, have good endurance, good FTP, good VH2 max, et cetera, et cetera, et cetera. And so likewise, if you're Body requires fuel across all of these, a different fuel necessarily across all of these different intensity ranges. Removing one of those fuel sources kind of doesn't seem like a good idea. If you, like you said, if you, maybe you can concoct scenarios for very specialized forms of racing where you can only, where you would only need one type of fuel or the other. The more sensible popular diet advice is eat like a well-balanced diet, but if you want to lose weight, and still be training. You just have to eat a little bit less. Completely cutting out one of those primary macronutrients is not going to help you in terms of your performance, especially if you're trying to complete hard workouts at the same time. And unfortunately, there are no shortcuts. Yeah. And I think that's the other thing is that people hopefully are realizing that training is the thing that makes you Better, and diet should enable that, not the other way around. You shouldn't think that this diet is what is going to help you, therefore, sacrifice your training to be able to stick to your preferred diet that you think is going to make you better. Great way to wrap it up. 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