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And that is for kind of off hours questions. If you got something on your mind, you want to type it in before you forget, head over there and go ahead and ask. And we'll kind of tackle those as the podcast goes on over the next couple of months. And today we have a really, really fun interview. And I'm very much looking forward to, well, it's already done for me, but if everybody listening, then it's about to come up for you. And I've been reading up on this topic for a long time, energy. And it's way beyond carbs and fats and all that kind of stuff. And today's guest is a, he's a very special guest because he's an expert on this topic. He's, you know, he has done a lot of the research. He works in a lab that's done a lot of the research on energy and energetics that I've been reading lately. And today we're going to be talking about a lot of concepts that I find are largely unknown in the cycling world. And they're kind of, they're out there to some degree, of course, but it seems to be a lot more crossover with the general fitness community, more with like strength and physique sports, which is also kind of where our guest comes from today. Those are kind of his backgrounds, both in competing and coaching. And, and we're also going to talk about how these concepts apply to the endurance training world. Because one of the things that that the lab he works in is working on as you'll hear is a bunch of really highly energetically taxing things. Like, you know, what happens if you run a marathon every day? What happens if you run, like physically run across the country with your own two feet? What happens if you are a pregnant marathon runner? Because these things are all highly demanding of energy. And, and how does it apply to cycling is a very, very big question and a big topic. And we are going to a future episode. We're going to be breaking down a bunch of the big papers on this kind of thing, including one of the ones that we that we talk about a little bit of detail today. But to introduce this topic, I really wanted to have an expert on and I'm so happy that I finally got Eric Shreksler onto the podcast. And he, if you, you probably have heard the name, if you are kind of in the fitness side of the world, rather than just the pure cycling side of the kind of media and stuff. He's a postdoc at Herman Ponser's lab. And he is a formerly of stronger by science. He writes for the mass research review. I am a lifetime subscriber to mass. He's also the host of the Iron Culture presented by mass podcast and front page fitness. And he's an absolute wealth of information on this topic and a bunch of other topics. And we probably could have spent five hours talking about stuff. And we wouldn't have even scratched really the surface. So, and so if you would like to check out any of the papers that we touch on in this episode, head over to empiricalcycling.com and check out the podcast notes for this episode. And one of the things that we talk about today really is the, what's known as the constraint energy expenditure model. And some of the ways that it gets misinterpreted, kind of general application of it, kind of where do you expect this? We also talk about doubly level water and and a measuring measuring energy expenditure and how it's some practical ways to think about energy expenditure. And at some of the edge cases that may or may not happen in the Iron Cycling and also with general weight loss. And also dip into body weight and stuff like that in this episode. And I got to tell you having come from just listening back to this interview. We did not really approach it with much nuance, I think, in part because in the world where he's from in the general fitness world. In terms of strength and physique sports, body weight manipulation is actually very normal. And in the cycling world, it's a problem really. So we didn't really get into much nuance when we touch on it. We kind of approach it from professional coach to professional coach. Our kind of attitudes towards it is reflected in this way. And it really is, I think I tried to get across, you know, that this is probably, you know, some of the considerations that we're discussing in the cycling world. And the cycling world is not for amateurs like not even by a long shot. So and we also didn't really touch on things like health risks and really didn't dig that deep into differences between endurance sports and strength of physique oriented sports like wrestling, body building, powerlifting, that kind of stuff. Field sports a lot of the time and just general kind of fitness. So those are some of the caveats. And so we will on the podcast be approaching a lot of those topics from very nuanced angles in the future. So please don't get at your pitch forks yet. We've got a lot more guests and experts lined up to discuss this kind of stuff. So I think that's enough of a preamble. And with all that in mind, here's my interview with Eric Drexler. I really wanted to talk to you specifically not only because you work in the concert lab, but also because of your background in coaching and the crossover between actual scientific training I come from the biochemistry world myself. And the rubber meets the road in coaching is actually somewhat rare. I know not for you and the folks at mass. But it's a little more rare in the cycling world. And I think especially one of the things that I wanted to bring you in for was that the cycling world is the understanding of dieting and especially energetics is actually not very nuanced. And I think a lot of people in cycling world focus more on carbs and fats and things like lactate, but not enough about energy. And I couldn't think of a better way to start making content on this kind of stuff than to be talking to you. So my first question really is what exactly does the concert lab study and what's your role there? Yes, so my role has kind of shifted recently. So I started out as a postdoc there and really as a unique postdoc there because the concert lab is housed within the department of evolutionary anthropology. So most people that come through hermins lab as a doc student or as a postdoc are coming at it from biology or evolutionary biology evolutionary anthropology. So that department largely focuses on primate evolution. And if you look at hermins research over the years from his PhD to what he's doing now it really has kind of drifted into a much more applied and kind of human focused kind of direction not not to say he doesn't continue doing animal work, but it has shifted kind of over the years. So it's really hard to imagine me working so closely with hermins 12, 15 years ago, but as his research is kind of drifted into this space there's now room for someone like me to kind of join in on the fun me being an exercise physiologist sports nutritionist by training. So I joined in as a postdoc recently accepted a faculty position here at Duke moving up the ladder so to speak, but I still I do my teaching at a different department that's more exercise focus, but I still am doing my research out of hermins lab there and essentially what we study is energy expenditure. And so you know if you look at it from an evolutionary perspective the human body is a really fascinating machine that it really burns a lot of calories and throughout our entire evolutionary history we've had some really interesting trade offs to consider you know when you look at us compared to our closest relatives from an evolutionary perspective. You look at how different our GI tract is you look at how different our brain is and the energy need that goes with that brain and you start to see that how we use energy throughout our lifespan is not it's certainly not an inconsequential consideration in terms of the viability of our species. So there's there's this whole life history theory that focuses on how humans allocate energy in order of you know in order of priority or preference throughout the lifespan. And so in our lab we we of course study energy expenditure across the world.
many species to get a better understanding of how different species utilize this critically important resource. I mean, there's essentially very little more important than determining how your energy is going to be allocated toward doing the things that keep us alive. But we've branched out lately into studying some extremes. So, looking at how do we manage energy budgets under conditions that would really kind of push us to our limits. So, looking at ultra endurance athletes, we've got a project that a PhD student did a dissertation on recently on heavy endurance training in the context of pregnancy, where we have this kind of double whammy of massive energy requirements. And so, we do a lot of energetics looking at a variety of different questions related to either the extremes that we see or questions that, of course, have some relevance to public health as well. So, that's kind of our sweet spot these days. Yeah, and you mentioned our kind of closest evolutionary relatives. And I think it might be interesting to talk about like this difference between us and gorillas. Like, why are they so jacked and lean and why are we so kind of fat and skinny comparatively? Yeah, I mean, and this is one of the areas where I have to be careful because I still am very much an exercise physiologist who shows up to an evolution department. I'm like, what am I doing here? So, I'm probably not the best at laying out the entire theoretical foundation, but it is true. Like, when you look at a gorilla and you look at us, the differences are astounding in terms of, of course, just the sheer mass and muscularity is an obvious one. The brain size relative to body size, just the depth of cognitive capacity that we have relative to a gorilla. And then the diet and the gastrointestinal tract are so tremendously different. I mean, gorillas eat just kilogram upon kilogram upon kilogram of plant material all throughout the day, just kind of chewing on this rough, you know, really fibrous plant material. And the reason they're able to do that is because their GI tract is so fundamentally distinct from ours in terms of how they're able to extract protein from the diet, extract, extract energy from the diet. And so, what you see broadly speaking is that in our human evolutionary history, we kind of gravitated toward a strategy that really prioritized, you know, making sure we have this really high capacity brain, high capacity in terms of both cognitive, you know, computational power and also just energy requirement. You know, it takes a lot to keep a brain going. I think the brain burns approximately, I think it's about 200 calories per kilogram of tissue every day. So we're talking about a very energy intensive organ. And one of the ways that we've kind of made that work is by over time, you know, our GI tract is much shorter than that of other primates. And what we do is we kind of gravitate toward a diet with very high energy density so we don't need to have this really extreme level of, you know, when you look at a gorilla, they're just constantly doing this fermentation of these just massive amounts of plant material. And we've kind of shifted to a more streamlined GI system where we are seeking out energy dense foods and nutrient dense foods so that we can kind of get away with having this much more concise GI tract in terms of its architecture and function. So very, very different strategies. And I wouldn't really want to go ahead to head with a gorilla in any physical capacity, but when it comes to building the internet, we're beating on by a mile. Remember that gorilla Coco who could communicate in silent was I always wondered, did somebody ever ask for how much can you bench? That's a good, you know, I actually have met somebody and chatted with them who was at the place briefly where Coco was, but I think they actually got there after she had passed. So she had heard all the kind of stories, but didn't get to interact with Coco, but yeah, certainly a fascinating tale for sure. Definitely. Okay, so back on topic. So with measuring energy expenditure, there's a couple ways to do it, but I, if you could dive into the more quantitative ways to do it, because I think a lot of people at this point have probably heard of doubly labeled water, but people may not have heard of things like the weird equation and people may not have heard of like a metabolic chamber. So, so what is doubly labeled water? How does it work? And how does it actually end up measuring energy expenditure? And like, what's the approximate error on it compared to something a little more rigorous like a metabolic chamber? Yeah, so, you know, when we look at energy expenditure, you know, coming from an exercise physiology lab, I was used to a fairly crude way of doing it. So, in exercise physiology, you know, for resting metabolic rate, we'll pretty much get you in there and do indirect calorimetry. And, you know, folks who are really into cycling, very well may have engaged in some indirect calorimetry in the past, right? So, if you've ever done like a VO2 max test where they had you wearing a mask, you were doing indirect calorimetry on a metabolic cart. We used to do a lot of, you know, exercise testing with indirect calorimetry where people are wearing the mask, we're measuring the air going in, the air coming out. We also would do resting metabolic rate with indirect calorimetry via metabolic cart. And basically, the metabolic cart, what we're really looking at is, you know, air is coming into your body, air is going out of your body. It's coming from the ambient room, going into your lungs, you know, you're doing gas exchange and then you're expiring, you know, the residual, what's left. So, we're looking at a combination of comparing the air going into the air going out. How much oxygen seems to be getting consumed by your body and how much carbon dioxide is being put out by your body. And so, we'll end up putting that into the weir equation, like you mentioned, and kind of figure out, okay, based on, you know, the exchange of gas, we can kind of work backwards with all these physiological and biochemical calculations and work our way toward how much energy, how many calories are you actually burning either at rest or during some kind of exercise activity like if we're doing a VO2 max test. Now, indirect calorimetry, like with a metabolic heart like that is it's really great for certain things. It's great for measuring expenditure and, you know, gases during exercise, for example. But it's pretty limited when we want to start extrapolating out to to things like total daily energy expenditure. Because basically unless we're going to have you just stand next to that cart all day and just breathe into it tethered by, you know, a three to six foot tube. We put the cosmic thing on your back, yeah. Yeah, I mean, and yeah, there are portable, portable indirect calorimeters that have become a little bit more accessible these days, but there it's still a very unusual way to go about life. And so the question is, how do we actually measure total daily energy expenditure in a way that's more reminiscent of day to day life and the life that you are living, you know, because ultimately, that's what we're trying to get at is on your normal day, how many calories are you burning? So like I said, a lot of times with with indirect calorimetry, people are stuck in the situation where they basically do a resting test, do like a 30 to 60 minute resting metabolic rate. And then they'll just kind of figure out how active are you generally and just multiply that resting metabolic rate by something and say, okay, we think your total expenditure is probably around here. And that's obviously subject to considerable error just because of the massive assumptions that that were making, particularly with that multiplication process. So you could do a little better than that and use a metabolic chamber. And we have one of those in the Ponser Lab here at Duke. And about metabolic chambers really simple, it's using the same premise of indirect calorimetry. We're still measuring the gas going into the room and out of the room, but instead of tethering YouTube, the metabolic cart by a little tube and wearing a mask, you know, we're basically creating a little dorm room for you where you have your little sink and your toilet and a bed and a desk and a television. You know, we can bring in a walking pad or a stationary bicycle. So we basically, for my office. Yeah, exactly. We create this kind of little self-contained room where we can say, hey, stay in there for 24 or, you know, people can vary how long they want to keep you in there. But it's usually about a day. And basically say, yeah, we're going to get you when you're sleeping, where you can get you hanging out at the desk. Maybe we allow you to do some exercise on a walking pattern of bike, like I said. And we are going to, at the room level, kind of make those estimates based on the gases going in and out and kind of determine how many calories you're burning from that perspective. And that's better than just kind of getting this little snapshot of 30 minutes and trying to do a bunch of multiplication. But there's still shortcomings with that because obviously I would imagine most people where, you know, were interested in measuring their energy expenditure, they don't actually live their whole day in a tiny room. They go out and do things. And so we can try to say, hey, get on the walking pad and do some of this, do some of that. But we're really not replicating their day to day life. Right? And so that's, in my view, where doubly labeled water really comes into play as a major major.
your upgrade. So doubly labeled water, pretty much anyone you ask is going to say it's the gold standard for measuring total daily energy expenditure. And what we're doing is we're giving you water and it's labeled doubly. There are two ways that we've labeled it, right? So if you think back to high school chemistry, you've got your periodic table of elements and each of the elements has its own atomic mass. And so water is H2O. We've got the hydrogen part and the oxygen part, hydrogen usually has an atomic mass of one, oxygen has an atomic mass of 16 typically. So we can give you a labeled version of hydrogen that is actually H2 instead of H1. It's labeled because it has an extra neutron giving it more atomic mass. And when we put that under a, if we have two samples of water, one with normal hydrogen, one with the heavier hydrogen, when we put that in our laser analyzer, we can tell the difference between the two and calculate the concentration. So we can label that hydrogen, turn it from hydrogen one to hydrogen two. We can also label the oxygen, turn it from oxygen 16 to oxygen 18 by having a couple extra neutrons in there. And so basically what we'll do is we'll bring people in, get a baseline urine sample to figure out these different versions of hydrogen and oxygen. We call them isotopes. And these are stable isotopes. They're non-radio active. But we basically get a baseline sample to figure out how much of these isotopes are in your system just from background exposure because these are naturally occurring isotopes in very, very small concentrations. So we want to figure out what your background level is. Then we give you a carefully measured dose of this doubly labeled water which is scaled to your body mass. And five or six hours later we'll get a second sample where the little dose of water we gave you, it's usually like 100 grams or 100 milliliters worth of water give or take. We give that a few hours to kind of basically distribute all throughout your total body water pool. We want to completely dilute it throughout your entire system. So then we'll get another urine sample at that kind of peak enrichment is what we call it, where your total body water pool is maximally enriched with this labeled water. And then we'll just collect a few more samples over the course of the next week or so and kind of see how quickly the labeled oxygen is leaving your body system and how quickly the labeled hydrogen is exiting your body. So you can think about it like imagine your body is like a big fish tank and we put a drop of blue dye in it. So immediately it's going to dissipate throughout the entire tank. And then every day we're going to take a liter out of the tank and we're going to put a liter of normal water back in. So over time as you're using water and water's exiting your body we're diluting that initial sample of the double labeled water. So what we're trying to do is kind of look at the rate at which your body's eliminating this labeled hydrogen and oxygen from the system. And so basically then we do a bunch of math and we figure out based on the slope of elimination for hydrogen and oxygen we can work backwards and figure out the two things were were typically most interested in. The three things that you really get from double labeled water. Number one we can get a decent estimate of your body fat percentage. Number two we can get a really good estimate of your water turnover on a day-to-day basis. So we get a better idea of your water needs daily. And then of course what everybody's interested in is we can get your total daily energy expenditure specifically by comparing by looking at the difference in the elimination rates for oxygen and hydrogen. So that is the method in a nutshell. I'd have to double check the literature on the kind of most up-to-date estimate of exactly what percent of what validity we have. Because obviously the method is always getting tweaked and changed and updated and improved. You can always update the equations we're using things of that nature. But without question, the number that you get from this you can really take to the bank and you can really utilize in terms of assessing your daily energy needs. And it is certainly considered the gold standard and the best we got at this point. Right. So it's not going to tell you that your energy needs are like 2500 when they're really 3500. It'll be like it's 2500 and it might actually be like 26 or 24 kind of. Yeah. Yeah. We can really take this not like I said. I'd have to double. I don't want to be wrong. I took my comprehensive exam. My lectures are used to be hedging all the time. So I don't know. When I took my comprehensive exams as a master student, one of the smart ass doc students told me he had some advice and I said, oh, this will be good. He said, don't be wrong. It actually was good advice because it's okay to say, you know, I can't give you the exact number with a high level of confidence at this time because it's always getting updated and changed. So, but I can tell you that this is the type of thing that you can actually realistically make individualized nutrition changes based on this number. We are going to be within a margin of error that frankly is smaller than the margin of error that's allowed on your food labels. So it's, you know, like, because you know, food labels are allowed to have up to like a 20% variance in terms of their caloric accuracy. So, so yeah, we absolutely from this are getting an individualized highly tailored and precise estimate that you can actually act upon in terms of setting your targets for nutritional needs. Yeah, and that that nutritional error is why I always have a couple extra chocolate chips. Yeah, why not? It's a, yeah, it's my perfect excuse. So how did the, well, what is the constrained energy model and how did this come about? Yeah, so the constrained energy model, you know, Herman is a Herman Ponser's a pioneer in that area and it's been about 10 years since he published to the the first like big paper that you can kind of view as like the constrained model manifesto of like, Hey, I've been chipping away at this idea for a while and enough evidence has mounted here that I'm ready to kind of put a name on it and present it all as kind of a tidy bundle of information. So the constrained model, you know, one of the things that I think really I don't want to speak for him, but it seems to me the story goes that, you know, what really caught Herman's eye is doing research using doubly labeled water, getting like I said, this is very precise estimate of daily energy expenditure across very different populations. So of course, you know, we're based out in North Carolina, we're going to be doing research at the time Herman wasn't in North Carolina, but, you know, in America, we're going to have some research we're doing on sedentary populations, likely who have, you know, overweight or obesity in terms of their BMI category. So we see the energy expenditure that we anticipate with a cohort of people that is overweight or obese and highly inactive. But, you know, we also we have this great collaboration. It's a big acronym called Peacán. It's population, ecology, something, something aging network. But a big collaboration where we work with people all over the place who are doing research and all these diverse populations all over the planet. So, you know, talking about like hunter-gatherer communities, talking about very small scale pastoralist communities, you know, communities that are not industrialized economies where they do either subsistence farming or hunting gathering or small scale herding to kind of meet their needs. You know, they're not doing crop production for commerce reasons. It's just they grow what they need and they eat it or they hunt what they need. And so these are just fundamentally very different lifestyles. These are populations where in many cases it's not unusual to see individuals averaging 30, 35,000 steps a day compared to the tiny fraction of that that we see in industrialized economies. So, you know, we within our Peacán network we've got folks who have done studies in Siberia, South America, Africa, Southeast Asia. I mean, just all over the world. Different climates, different latitudes, you name it. And time and time again, you know, Herman was kind of realizing that you look at these two cohorts with, you know, dramatically different activity levels. And they were generally converging within a fairly tight range for total daily energy expenditure on average once you correct for body mass. And so to him, that was a very eye opening if not jarring observation, which is, you know, coming from the exercise science world, we always tell people if you want to burn more calories, move more. And to an extent that is true. But what was really catching Herman's eye was like, well, I'm doing this study on sedentary folks who work at desk job in Philadelphia. But then I'm also doing these studies on people who are, you know, hunters in the hodza community in Tanzania and they take 33,000 steps a day. And once I correct for their body size, the total daily energy expenditures are not all that different. And that really gave rise to the constrained energy expenditure model, which basically suggests that yes, generally speaking, if you do more activity, you'll burn more calories than if you did very little activity. But the relationship is not linear. So it's very natural for us to assume if I, let's say, I'm doing my cycling training. I'll try to stay on brand here. And I'm going to add enough work to my daily workout. Let's say I work out seven days a week just to make things easy. Pretty average. I'm going to add an extra 100 calories worth of effort. And so reasonably one would expect, okay, I'm bumping my training load by 100 calories a day. I'm doing it seven days a week. My total daily energy expenditure will increase by 100 calories per day.
But what we tend to find is that's usually not how it works. The number your total daily energy expenditure typically will go up when you increase your training load. But if you increase your training by 100 calories a day, on average, it may only go up by maybe 70 calories instead of 100 calories. The other 30, it seems that our body has numerous potential mechanisms by which it can strain less essential elements or components of total daily energy expenditure so that we're essentially conserving energy. And what's interesting is that it's not just kind of a flat tax off the top where it's like, okay, every time you try to increase by 100 calories, the tax is 30 percent and you're only really getting 70 percent of what you put into it. It's very non-linear in the sense that when folks are, let's say you are extremely sedentary and you eat more calories than you need on a daily basis. If you increase your activity from virtually nothing to 100 calories higher than nothing, you're probably going to be getting the lion's share of that increase in total daily energy expenditure because there's no reason for there to be a massive constraint there. You're in positive energy balance, there's all these calories to be had. Your body's not going to really be getting any signal or any indication that we need to start being very conservative about energy use. On the flip side, you can imagine that you are in a community where caloric resources are relatively scarce. You already are averaging 27,000 steps a day. You've basically lost five pounds from your top body weight and now you're kind of out of plateau at your current body weight, which is quite lean. If you increase 100 calories worth of exercise daily from there, now you can start to see a scenario where your body's like, "Okay." Of course, I'm assigning a level of cognitive thought here that's obviously not real. You could understand why we would evolve with mechanisms that say, "Listen, you're not eating very much. You're doing tremendous amounts of physical activity. We probably need to have some level of constraint on total daily energy expenditure to prevent curing rapidly into a starvation, threatening kind of situation." That's the idea with the constraint energy expenditure model is that our body has mechanisms where if we really push our physical activity or exercise level super high and especially if we're underfueling in that context, we have the ability to, let's say, reduce some of our non-exercise physical activity expenditure or let's say, reduce some elements of our basal energy expenditure in order to soften the blow and give us a little bit of cushion between us and basically a fast track to starvation. Actually, one of my favorite bits of trivia that really illustrates this is the average what is the average weight gain in America is about about a pound a year, which roughly is like 10 calories a day. I heard this on a podcast five or 10 years ago. My first thought was, "Are we all really overeating by just one fork full? You've got to be kidding me." That's impossible. Then I heard this and I went, "Oh, now it makes perfect sense because I think that a lot of people when they hear this, because it's typically, it's been studied in constrained, you don't have enough energy, your body needs to compensate somehow, but it goes the other way too, doesn't it?" Yeah, absolutely. For sure, it is very fascinating when you start looking into the research on what magnitude of overeating would it really take to develop obesity over a lifespan? Yeah, it could be as simple as a mismatch of 1%, where you're overeating by 1% in perpetuity, and if you're not reaching a plateau and every time your body gets larger and your expenditure goes up a little bit, you maintain that 1% overeating. You can kind of explain the gradual weight gain into the obese categorization that we observe over the lifespan. One of the things that's really cool is Herman, he wrote a paper in this really cool special issue for a journal like a year or two ago. It was a special issue where they got together like really legit experts with very different views. They said basically write an article about how we got here with the obesity epidemic. What is it that's driving obesity in humans? They have representation of people talking about theories that as our diets get relatively lower in protein, we kind of over-consume to meet that gap and keep eating until we meet our protein demand and now our calories drift higher. People writing about the effects of insulin, the carbohydrate insulin, motlicks, all these different models that people have thrown spaghetti at the wall to see what sticks metaphorically. Herman's paper was like, "Hey, could it be as simple as that were primates?" He looked at, I think, a couple dozen species of primate and basically compared the good life to the hard life. The hard life being when you want to eat, you got to go out and hunt it or gather it versus the good life meaning you're good, you're not really being, you're not getting chased away by predators every day, you don't have to go out and hunt. With all these different primates, he basically compared a wild group of the primate to a primate who lives in a cushy zoo or sanctuary where there's no predators, the food gets delivered to him on a regular schedule, it's delicious fruit, they don't have to go out and eat all the fibrous roots to try to get some calories. For the human comparison, he compared kind of like hunter-gatherer societies to industrialized economies where people have easy access to abundant caloric resources. It seems to be kind of a part of being a primate, living the good life. We tend to overeat just a little bit, essentially in perpetuity and that's how we kind of get where we get. To your point, the relationship, like I was saying, it very much differs depending on context and the two big elements that seem to be dictating the magnitude of compensation as we currently understand it. Number one is how much are you eating? If you are severely under-eating relative to your expenditure, we can expect a higher level of compensation, which is very intuitive. Number two, how active are you? We tend to find the most compensation in people who are doing very extremely high levels of physical activity, not in totally sedentary people who decide they're going to start walking a couple miles a day. I think maybe kind of the thing I was maybe trying to get across is to have a more intuitive understanding, to not quite get into the dual intervention point model, but to just think about the constrained energy expenditure model as more like the body trying to match output to input. Right. Yeah. Exactly. I think that's a good way of putting it. For example, why would we need to pump on the brakes if a person who is totally outmatching their intake relative to expenditure, they're eating 300 calories per day more than they actually need? What would be the need? What would be the evolutionary pressure to say, well, if you increase your calories by 100 in that context, you're still in a caloric surplus. Why would we need to apply any brakes to energy expenditure in that context versus if you think of a very, very lean individual who is already under-eating relative to their energy demands or their energy expenditure? It is a very threatening thing for them to continue bumping that expenditure up and up and up and growing that taxes. I think the whole cycling world, why don't you? Yeah. It's a very threatening thing. What's really interesting, I came into this not from an endurance perspective, but from a bodybuilding perspective, which is a really unique case study in the body adapting to these very unique constraints. What's really interesting is you talk to body, I'm sure it's somewhat similar in cycling, but you talk to bodybuilders. What's your least favorite thing about the sport? I'll start talking about all these things that happen late in what we call contest prep. As a part, bodybuilders, when they're not about to compete, they may be 30 pounds heavier than they will be by the time they actually get on stage and compete. The process of getting lean and getting down to that 30 pound weight loss, so they're really ready to go on stage with virtually no body fat. They call that contest prep and people always talk about what's the worst part and they're like, contest prep, I'm cold all the time. I have no libido. I can feel the symptoms of low testosterone. Literally, what they're doing is pointing at the body, essentially saying, "Well, if you're going to be doing this much exercise and if you're going to be underfueling this much, I'm going to start cutting into some basal processes to save some energy," which means, "I'm not going to keep cranking out all this thyroid hormone that you're used to." That's why your energy expenditure drops and you feel freezing cold all the time. You have no business engaging in any reproductive activities when you are this in such a dire situation energetically.
And so that's where we start to see drops in testosterone. Your body's not going to waste the energy to make it, and it's not going to put you in a situation where you're utilizing your reproductive system to create more offspring because that's not a good look for you right now when you barely have enough calories to go around to make ends meet for yourself. And so we start to see these energy requiring processes related to these hypothelamic hormone cascades are all getting turned down likely as an energy conservation response. Yeah, so what are the more nuanced categories of the energy constraint that we're feeling? So you mentioned the metabolic adaptation. I know you did a lot of research on that before you joined Ponzer's lab. So why don't you talk about that a little bit and also the other categories of exercise energy compensation and also efficiency of movement? Yeah, so when we are breaking down total daily energy expenditure, there's a million different ways that you could categorize it depending on the context. But the way I like to think of it as it is basically four separate compartments or four different components you could say. So we've got our kind of resting or basal metabolic rate, which is just the calories we need to get by just existing as a human. So when you're sleeping, this would be your sleeping metabolic rate, which is exactly what it sounds like. And then when you're awake, we call it your basal metabolic rate. And you could think of that as, you know, if for whatever reason you're going to have a day where you woke up but never got out of bed, never ate, you just laid there and looked at the ceiling for a while. The calories you burned on that day would be your basal metabolic rate. But on top of that, there are other things that require some energy in our typical day to day life. One of the simple ones is the thermic effective feeding. And that's just the calories that it takes to ingest, digest and metabolize food. So all the calorie expenditure associated with the process of eating things and then getting those nutrients where they're going basically is the thermic effective food or the thermic effective feeding. Then we've got our exercise activity thermogenesis, which is our structured intentional training dose in the context of cycling. So that is your mileage that you're putting in, whether you're on the bike or maybe you're mixing in some resistance training, maybe you're mixing in some cross training, you're in the pool, you're doing some running. This is your structured exercise training calories. And then everything else kind of falls into this bucket that we call non-exercise activity thermogenesis. And this is everything that exists. You know, I kind of painted that picture of you just laying in bed all day and doing literally nothing. So that's one end of the spectrum. The other end of the spectrum is when you are actively engaging in intentional structured exercise training sessions. All activity that falls in the middle kind of gets caught in this bucket that we call non-exercise activity thermogenesis. So a simple example would be you go walk from your front door to the mailbox to get your mail. That's clearly activity. You're not resting, you know, you're not purely at rest. But you're not going to count that in your training log, right? I went and got the mail today. So some cyclists do. I see those little three minute walks logged. But so that would be non-exercise activity thermogenesis. And it even goes to simpler things, you know, sitting up in a chair and maintaining your posture, fidgeting while you're in a chair. These are, at the end of the day, muscular actions that require more energy than simply laying in your bed and kind of not moving at all. And so this all falls in a non-exercise activity thermogenesis. And so to answer your question as concisely as possible, and we're talking about this constrained model or we're talking about metabolic adaptation. We're talking about a situation where your body is burning fewer calories than we could realistically predict based on all of our, you know, theoretical calculations. We're wondering where is your body cutting corners to make this deficit happen? Or to, I guess, shrink this deficit. You know, clearly your body's taken some shortcuts to conserve energy. Where are these shortcuts occurring? So far, the two main culprits. And it's very, there's a lot of debate over exactly where these calories are coming from. But right now, the leading theories with the most evidence behind them have really been zoning in and kind of focusing on these basal processes and non-exercise activity thermogenesis. Those are the two areas where we seem to be seeing the most happening in terms of potential constraint of energy expenditure. So like I said, bodybuilders know this at a very visceral level, especially on the basal side. You're in this big caloric deficit. You have almost no body fat left. You're still losing weight, but very slowly. You'll notice things like, like I mentioned, thyroid hormone and testosterone will fall out of the reference range almost always. You'll notice things like your fingernails and your hair are growing more slowly. So really interesting things where you can tell. Like yeah, my body is just instead of spending the energy required to grow my fingernails at the normal rate, which requires assembling all those proteins, all the energy that goes into that process, your body is saying, no, we're going to slow that down and save the calories while we can. And then on the non-exercise activity side, some of this is kind of a subconscious response that impacts volitional activity, meaning when you're really feeling fatigued in this state and you realize you didn't get the mail this morning, are you really going to go out your door and get it in the evening? Why not pick them up tomorrow morning? So it's pretty full sometimes. And it gets pretty full. Yeah. So it's the skipping out on things because you're like, I just can't be bothered. I remember I was prepping for a bodybuilding show when I was working on my PhD and people came into my lab and they point, I wouldn't have ever noticed this on my own, but they pointed out to me when I was really pushing hard. They were like, bro, you're like melting onto your desk right now. And I was like, what do you mean? And I just, I didn't even realize it, but even just the energy to sit up straight, it was gone. And I was changing my postural characteristics of how I would sit or stand throughout the day to conserve energy. I fidgeted less, things like that. So some of this stuff impacts volitional non-exercise activity and some of it's purely non-volitional and you wouldn't even notice it until somebody pointed it out. But these are the areas where we see the most. Now there have been some studies you mentioned like mechanical efficiency and things like that. And you can look at mechanical efficiency from different levels depending on, I'm not like a biomechanist. So anyone who is that's listening like cringe is like kind of, you know, can flate different concepts. Some of them to your dms. Yeah, perfect. But basically, you know, it is true that, you know, over the course, you know, if you are kind of in a deficit, caloric deficit, burning more calories, then then you are consuming and you're kind of in as you're losing weight, you're going to see more of this constraint kind of setting in most likely. You know, it is true that as you're losing weight, that is going to impact the energy cost of your exercise bouts. If that's the only thing that changes, right, you doing that exercise about at 181 pounds energetically looks different than you doing that same exercise bout at 168 pounds, for example. So there's that component, but there's also, there's been studies where they look at people before and after weight loss and they measure the efficiency of cycling and they actually use little weights to replace the leg mass that was lost. And so they're saying, well, I want you to do the exact same workout on like an electronically looked, break their gometer so we can control the wattage and the cadence and everything, you know, really highly controlled cycling workout. But we're going to have you lose some weight, experience all these endocrine changes I talked about, but then we'll make sure that the actual legs that are pedaling weigh the same as they used to. And even with that weight replacement, there have been some, there have been a couple small studies indicating that even just the mechanical efficiency of cycling can change and you can become a little bit more energy efficient after that weight loss has occurred as some of these compensatory neuroendocrine changes kind of start setting in here. Now, it is true. I should caution that when it comes to like a competitive cyclist, I think a lot of people overstate the impact of that mechanical efficiency because if you dig into those papers, it seems to be most prominent at super, super, super low power outputs like power outputs and a cycling workout that are more compatible with like you walking to get your male than you doing your training about that day. And the higher the intensity goes, we start to see that potential change in efficiency going away. So I try to really reiterate that to me, it looks like changes in resting or basal processes, play a role. Like changes in some of these non-exercise processes, play a role, thermic effective feeding and the actual energy cost of your training session aside from changes in body weight impacting it, those seem to be less likely to be the culprits when we're trying to fit
figure out where this energy's going. - Yeah, and you mentioned a bunch of stuff that people can kind of consider qualitatively because cycling is an incredibly quantitative sport because almost everything we do goes through a power meter. So we could be fairly precise about what we're spending how much. I mean, efficiency calories, like it's kind of plus or minus a few percent here and there. But we can make some rough estimations. And I think a lot of people are experiencing, in my experience anyway, 'cause I coach a lot of people, like I've got a bunch of other coaches, and we coach a lot of people, and I do a bunch of consultations every year with people who want to keep coaching themselves. And one of the most common things I hear is like, well, you know, I'm really lazy. I don't have the energy to play with my kids. My libido is pretty low, or like I'm cold all the time. My sleep is really disturbed. And, but you know, my calories are, I'm eating enough. I'm like, are you hungry? They're like, yeah, but I'm eating enough. It's like, okay, let's back up a step here. And so my fascination with bodybuilders, 'cause I'm injured, and so I've been doing more strength training than cycling myself. And so my fascination with bodybuilders and the strength training world has led me down to all this stuff. And you know, I found the mass podcast like a couple months ago. And then you guys merged with Iron Culture, and I was like, oh my God, I've got 300 more episodes to tell us to in the back catalog you kidding me. I mean, if you caught up with the ones that you guys did recently. So this kind of stuff has been incredibly helpful to me as a coach, and I'm hoping it's helpful to people out there listening. And so I wanted to get into a little more on some of the finer details on this kind of stuff. And also some of the misinterpretations that can happen. And I think one of the ones I've seen, which always made me laugh really hard, which is that they've seen that big concert paper. And they're looking at the average expenditures like 2600 K Cala Day. And there's the number one misinterpretation I always see is I guess this means nobody can burn more than 2600 K Cala Day. (laughing) And I'm like, there's some pretty big air bars on that number. - Yeah, yeah. So that is definitely a huge misconception. And yeah, when you look at some of the work we've done on athletes out of the Ponser Lab, you see that that's clearly not a claim that we would ever make. There's two distinctions to be made here. One is athletes who are eating a bunch of calories. Like you said, there's this kind of intuitive level of kind of approximately matching expenditure to intake. And so if you are in a situation where you can fuel really intensive training and put in this training day after day, obviously you're gonna be burning more than 2600 calories. So there's a paper from 2019, the lead author was Thurber and they were looking at folks who were doing race across the USA. And the average energy expenditure in that group when they were in the thick of it doing their training was about 6,000 calories per day. So yeah, you absolutely can burn a heck of a lot more than 2600 calories. When you look at research on rugby players, basketball players, other team sport athletes and endurance athletes, it's not at all unusual to see daily energy expenditures in the four or five, even 6,000 calorie range. And you can find case studies even go in north of 7,000 calories per day, which does bring me to the other thing, which is the duration of activity. And so that Thurber paper, what I really like about it is it kind of plots out a bunch of different things or events that involve high energy demand. So for example, race across the USA, the Tour de France, being pregnant, just a variety of different things that elevate our expenditure beyond the kind of normal resting level. And what they plot out is the relationship between how high we can sustain our daily energy expenditure regularly, that's on the y-axis and on the x-axis is how long is this event? So in the case of pregnancy, that's a nine month event. In the case of race across the USA, I think it ends up being about 140 days if I'm not mistaken. - That's the running race. - Yeah, there's something race too. - Yeah, it takes a lot less time. - Okay, yeah, well that makes sense. But yeah, the running race, I think, takes about 140 days, give or take something in that ballpark. But basically we can look at all these different events, some of which are one day long, some of which are two weeks long, some are 10 weeks long and all down the line. And we find that there's a massive, it's a very non-linear effect where if you wanna just make your expenditure as high as you can possibly make it for one day, it really just comes down to how much pain you're willing to live. - Watch your feet, your back, yeah. - So like, the way that we like to quantify it is multiples of your basal metabolic rate. So if your basal metabolic rate is 1500 and you burn 4,500 calories per day, that we've put you as a three, three times your basal metabolic rate is your current total daily energy expenditure. So the multiples of BMR, that metric, we can call metabolic scope. So metabolic scope of three is three times your basal metabolic rate. When we look at these ultra short term events that are like a day long, we're looking at metabolic scopes sometimes, in the like 13 range. But we find that it quickly drops off when you're looking at events that are like 15 days, it's gonna be really tough to find a metabolic, I'm sorry, about 50 days, 5, zero. It's gonna be pretty tough to find a metabolic scopes that are much above like six or seven. And what we tend to find is that over very long time scales, if you're gonna try to maintain a metabolic scope of 10 and do that for the next 400 days, we, I'm not saying you can't, but I'm saying we've never observed that. That's something that we just don't have in the literature. What we tend to find is that the longer this goes, your maximum sustainable metabolic scope seems to drop off pretty substantially. And when we're talking about long time scales, 9, 10, 11, 12 months, or you could think of it, it's just like if you wanted to maintain high expenditure for the rest of your life, what's like a realistic upper limit that we tend to observe, it tends to be about two and a half times basal metabolic rate. And so there's always gonna be, you're gonna find a zillion papers where this is another misconception that I'll get ahead of, but people will say, well, you said that the human maximum limit or upper limit or practical upper limit, however you wanna put it, is 2.5 times basal metabolic rate, but I just looked at this study where someone was doing six and a half times their basal metabolic rate. And so far, 100% of the time, the response to that as well, you're showing me their energy expenditure during an 11 day event. And if they try to maintain that workload for the next 700 days, we're gonna see that number dropping off. So that's another area of confusion. When we talk about how high it can get, absolutely, it can get higher than 2600. For short term events, it can get, essentially it's correlated with just how much you essentially hate yourself and are willing to punish yourself. And I guess I can get to Paris, yeah. I guess I could be more positive and say your level of ambition at the expense of your own acute comfort. But at the end of the day, when we're talking about longer term stuff, that was one of the reasons why one of our doc students kind of undertook a project of saying, well, if we know that pregnancy alone puts you up to like 2.2 times your basal metabolic rate at the peak energy expenditure when there's a lot of fetal growth happening. If we know that, what would happen if we layered on top of that like a fairly substantial exercise workload? And I don't think I'm allowed to give away too much about that study, but the short version is, you know, this upper limit of two and a half seems fairly robust, broadly speaking. And like I said, in short term fluctuations where you have a massive uptick in your training load, of course you can exceed that. But when we just kind of grab random athletes that are engaged in their normal day to day stuff that they've been doing for the last three years, yeah, generally speaking, we tend to find, the daily energy expenditure of, there's one paper that looked at, I think it was, if memory serves, it was like rugby, basketball, and maybe soccer players, and they kind of did doubly labeled water. It was like a systematic review. And yeah, basically these are all highly active folks who are running up and down the field all day. And the main thing that seemed to really dictate who's was higher was basically how big is your body, which correlates with your basal expenditure, right? So basically all three of those sports fell really well in line with them all being between two and two and a half of their metabolic scope, and just scaling up based on body size, which is exactly what basal metabolic rate does. - Yeah, and one of the things that I tell our clients who are like ultra-arrasers is that, you're going to go way beyond like the amount of food you can absorb in this time. Like I was doing some consulting for people doing like multi-day ultra-events, and I remember one of them said to me, like everybody loses weight, there's no way not to. Like you cannot eat this much, you could stuff your face all day, you could have grape soda from the time you get up to the time you go to sleep, and nothing's going to happen to you that's going to like make you maintain your body weight. And so I tell people,
You're really borrowing against your future energy stores. Yep. 100% yeah, and that's one of the things in that Thurber paper I keep mentioning, you know, that. Yeah, well, look at it in the show notes. Yeah, so they basically say like, "Well, what's going on here?" And it gets back to what we were talking about earlier, which is, you know, this kind of attempt to match expenditure to intake to some extent. And what we tend to find is if you are really trying to maximally fuel, which is not the case of like hunter-gatherers where we're finding that, you know, really surprising low, like 24, 2600 calorie per day expenditure, they're not eating 6,000 calories a day. They just aren't, at least not on a regular basis. But when you look at an endurance athlete who's like, "Oh, yeah, I'm going to force feed and do as much as I can with gels and powders and potions and you name it, I'm going to get as many calories in as I possibly can," it seems like they mostly tend to max out at a calorie intake level that is about two and a half times basal metabolic rate. Now, what is setting that limit? Is it physiological or is it more just this is kind of the inflection point where people just start to feel icky and they say, "I just can't do it anymore." Who knows? But that probably has a lot to do with why we're finding that. Essentially, you know, let's imagine, let's go with that idea that two and a half times basal metabolic rate is a caloric intake that essentially maxes you out in terms of how many calories you're absorbing from the diet every day. And let's say you're trying to maintain a metabolic scope of five over time and you try to keep doing it day in and day out. Basically, what seems to be happening is you're going to be losing weight throughout that entire process until you get smaller and smaller and smaller. And what seems to be happening is reaching a kind of body weight equilibrium and exercise expenditure equilibrium where basically you lose weight until that 2.5 times basal metabolic rate intake is functionally matched to your 2.5 times basal metabolic rate output in terms of expenditure. So it does seem like there's this kind of long term equilibrium and one of the big constraints on it is just how many calories can you get in. That seems to be a pretty big factor here. Yeah, and I would imagine that there's some distribution around that 2.5. Like maybe some people are more like 2.2, some people are closer to 3. And I would imagine that in the cycling world, you know, especially toward France, you could probably find people in the 3-ish range. It would be my guess. I actually have a model based on all of the calculations that have been in these papers. And I've got a 2.5 and a 3x BMR over the long term kind of looking at like body weight, you know, what's the approximate energy deficit. And like then, you know, for some people, the 2.5 model works better. For some people, the 3 model works better, usually more on the pro side. But it seems like, yeah, it seems like that is, in my experience anyway, like pretty robust. Yeah, and I mean, the thing is I've been doing stuff related to human physiology for way too long to ever pretend that there's a single number. You can only be a glutton for punishment and be wrong enough times for you to start saying, you know what? Let's assume that there is biological variation that exists because so far that is virtually always the case. So yeah, when we say, you know, it looks like very few people are really, you know, at least in the aggregate kind of average level looking at this group and that group and the other group. You know, it does seem like it's very a minority of folks who are really pushing well above this 2.5 kind of soft limit or soft ceiling. But at the end of the day, I mean, especially I think you mentioned kind of your higher level people maybe are kind of pushing into that three range or the model that assumes three is working better for them. I wouldn't at all consider it implausible to say like, hey, one of the things that helps them be very high level may be the fact that they're able to fuel more, which ultimately allows them to maintain higher outputs for longer. And at the end of the day, that's kind of the name of the game in cycling is get your output high, build up your capacity to do that and then keep doing it until other people can't. You know, yes. So yeah, I wanted to all be, you know, especially when you start getting into this is such a big distinction. One of the reasons I like kind of drifting from a background in sport and then drifting into these other kind of concepts is like, I feel more and more that I'm the person in the room almost always who has to remind everyone, you know that elite athletes are, these are not normal people because like the whole purpose of being elite is to be different than normal, right? So like, for example, like, you know, what you can give me a, you know, a pub med link that tells me how, how many calories the typical basketball player should burn. But you know, if I'm here at Duke University, we don't have the typical basketball player. You can see behind me. There's a, oh no, there's no video on this. There's a banner with our five national championships. Duke, the whole point of Duke basketball is to not be the typical basketball player. You know, we want you to be, you know, between six, six and seven, three and moving up and down the court like crazy. And so like, yeah, we don't expect our numbers to be average because that's the point. So it doesn't surprise me at all. Like, I would imagine if we expand out and focus more on individual rather than group level findings and we kind of get into more of these pockets of extremely elite athletes. Wouldn't surprise me at all if we see that there is some kind of biological variation with regards to the soft ceiling and that perhaps being able to push beyond 2.5 is ultimately an advantageous thing. And that brings me to one other tangent that I really have to get in. Oh, please. Before we, it's like one of those things. Like if I accidentally don't slip this in, I'll be kicking myself the rest of the day. So I hope I'm not going too far out of order here based on your plan. But one thing I really want to get across and this is on it's fresh on my mind because I've been going back and forth a little bit with Jose Arreita who who publishes in this, in this area quite a bit. If I'm not too careful, I tend to talk about this topic again, you know, the best thing we can do with our biases is be aware of them. You know, we can't shed them. We just have to try to call them out and see them and keep them in our mind. You know, I often think of these topics of metabolic adaptation and exercise energy compensation from the viewpoint of a frustrated bodybuilder who's saying, why am I not burning more calories than I want to? And why do I feel like crap when I'm prepping for a show? And if I'm not careful, I'll sometimes catch myself kind of pathologizing these adaptations or these effects. And so it's very important for me to catch that bias and make it very clear, especially in the endurance world to say, when we say that your body is kind of pushing back against some of this stuff and your body is trying to find some of these shortcuts and you're going to experience these drops in thyroid hormone and on and on and on and on. We have to be very clear that it's not necessarily a problem until it's a problem. You know, and so what I mean by that is, you know, Jose published a case study recently where, you know, they found a person who was, it was a case report of a very, very high level athlete and they were burning a tremendous number of calories per day. All indications suggest that they were unable to fuel adequately to keep, to actually maintain that for a long term kind of output. They were losing weight over the course of this race. It was an eight day race in this case. So they were not adequately refueling, but they were eating a lot. They had low thyroid hormone. They had oligomineria, I believe. Yeah, oligomineria. So disruption of the menstrual cycle. They had all these things that would cause you to say, wow, their body's really, you know, kind of, you know, they're pushing it pretty far and they're like you, like you said, they're kind of borrowing against their future energy. But at the end of the day, they performed extremely well. And so at the end of the day, you know, if you're experiencing some of these adaptations, but we say, okay, what was your goal? My goal was to perform extremely well and to not have any clinically relevant symptoms that actually merit medical intervention. Right? So you can have low T3 and say pack me an extra sweatshirt and that could be the end of it. Right? Like that. So it's really important not to get too biased in the interpretation of kind of treating this as a set of negative consequences or pathologizing it because it's always an issue. It's always a matter of magnitudes. Now I'll give you a different example. I know of a person who treated this individual, but they were a collegiate endurance athlete and they presented with a stress fracture of the lower leg, a tibia stress fracture. They were a runner, not a cyclist, a cyclist. But yeah, whatever. But they presented with a stress fracture of the tibia and they said, ah, bad news, you know, stress fracture. We're going to have to give you a walking boot. We'll check back in on a little bit. And, you know, this person had all the indicators, you know, low T3 all ago, if not amenoreic, the whole deal. They were underfueling, putting in way too much mileage, developed a stress fracture, came back after a few weeks, you know, however many weeks and the walking boot was destroyed. And they're like, what happened here? And they're like, oh, was I supposed to not do all my normal mileage with the walking boot? And he was like, obviously not. So they were like, this is insane. So they end up putting a hard cast on the lower leg and saying, well, we'll take care of this. So they come back in for their next checkup. The hard cast is mangled. And they're like,
Are you are you telling me that you were out there running on this hard cast that was like Taking up your entire lower leg and so then what they did was they they casted the leg into a 90 degree knee flexion so basically a cast all the way from the toes to the hip and said here's your scooter You cannot continue doing this and so ultimately that was one of those cases where it's like it was really obvious this person is chronically underfueling excessively chronically overtraining excessively. It's manifesting as repeated stress fractures and a Compulsion to exercise that is clearly pathological and so that was kind of a cascade of events that led to inpatient psychological intervention for a really severe compulsion for both overtraining and underfueling so The whole point is it's a matter of magnitudes You know if you're kind of flirting this line of like well technically I'm underfueling because no one can adequately fuel during the tour to France Then you know and then after the competition you know you get back into a more tolerable workload you're eating enough like It's always an order of magnitude and with clinical symptoms. We have to consider You know what is the actual net impact here and what are the trade-offs? We're willing to make for competitive success Yeah, and actually you bring up a good point because the the women's tour to France recently happened and the winner There's a lot of talk about her having lost weight into this and And you know in a sport where weight is such a big component of performance It's it's actually very common in the cycling world for people to go way too low for way too long The concept of like of get in and get out like in like in a bodybuilding prep is Foreign completely foreign to the cycling world. It's like you got to get to this low body weight and you're gonna stay there And one of the things that I've I have advised Some top level pros who I have to keep anonymous, but like one of the things I tell them is like look when you were and The you know when you were doing well in this race. I don't want to give up too much identifying information Like look you had actually gained weight before that your team wants you at this weight and you end up at this weight and then you Like I'm looking at your HRV right now Lee you were you were just fine then you lost weight into your big race And you were there for briefly and then you went right back up and that get in get out concept is like it doesn't exist in cycling It's it's it's almost always a problem of you know magnitude and duration and cycling. It's like yeah, it's never brief. Yeah And then that brings up, you know a whole other Application, I mean, it's really fun like I got into all this stuff because I was a wrestler and I was like this stuff's too cool Just exercise and nutrition and weight manipulation. It's very fascinating, but wrestlers almost kind of have the opposite issue where they're so interested in the whole getting get out thing that they don't maintain an Appropriate baseline weight prior to their their water cuts, you know, so I had a wrestling partner back in the day who wrestled at 130 and it was not unusual, you know, we had a weekly competition schedule most weeks where you know you weigh in on Saturday you compete you weigh in the next Saturday he come back in in Monday in Tuesday and He weighed in on Saturday at 130 by Monday in Tuesday. He'd be back up at 148 And it's like dude first of all you don't do an 18 pound weekly water cut and even if you do you better tell me that your starting weight was 275 not one not 148, you know, like you're losing like a six-level your body weight every week and then gaining it back in a day So like with wrestlers, we we always had the different issue where we had to say hey We're gonna do a water cut That's fine if you want to but it's gonna be a few pounds here and there But we need to actually get down to a sustainable body weight where you can be your best and so with wrestlers We find both issues either people think they're gonna look like a natural bodybuilder and before percent body fat and just Maintain that all year and somehow maintain their performance at a high level in a very strength and power-oriented sport Not gonna happen right so you need to be lean but not excessively lean and then you know Again, you have to make sure that the water cut you're doing isn't just absolutely Agreed you so anytime you're talking about sport and weight manipulation like you said it's a matter of what is our ideal pre-cut weight What is a reasonable duration for kind of getting down to competition weight and holding it and then what is our plan for rebounding under control back to a suitable kind of between competitions kind of weight and Pretty much across the board What whatever sport you're in that involves weight manipulation that the the timelines vary the short-term fluctuations and how you approach that are gonna vary in magnitude but ultimately that's the sweet spot is you need to figure out Where do we need to be coasting most of the time and then when we're in for how long do we actually have to get down to our kind of Optimized competition weight and if if we get there too quickly too slow or hang around too long we can ultimately run into issues Yeah, and actually that's um that's one of the things where I actually separate amateur cyclists and professional cyclists because professional cyclists the fitness is pretty steady for the whole time and you know you can you can do some amount of Fairly intense training and actually you don't even have to do that much intense training to maintain your form And and you can actually do some amount of weight loss into events but like for the amateur cyclist I mean people are more looking at like body composition for the long term and people are also looking more in terms of like You know, I just want to say healthy. I'm not going to be a professional at this and I want to make sure that I'm not you know I'm not screw myself in the long term and so So yeah, this is where I save the I save that get in get out strategy for like the top level pros and for amateurism like Yeah, you better not get to lean and you better not get through too quickly and so we end up actually doing a lot of like more Diating in the offseason and then okay We're gonna build fitness because like dieting when you're training hard two three days a week is like It's rough. Yeah, yeah, and that honestly that that goes without saying I mean we see this in power lifting a lot where people are like Yeah, I'm gonna do this water cut from my next competition. It's like brother You're about a 350 pound total away from like making noise in your weight class here There's no reason for you to be you know like and that's not to dismiss and obviously you frame it more delicately With with a client but it's like listen man like if you're telling me that you're gonna take third at nationals And you think if you drop a weight class you can get from bronze to gold then we'll do a weight cut like we that makes sense But if you're telling me that right now you're the ranked you know 358th in your state in this weight class and you want to drop down so you can get into the the high 2800s like this makes no sense like you what you need to be focused on is How am I gonna increase my bench squat and deadlift by a hundred pounds each over the next two years? Not how am I gonna lose seven pounds before this competition? You know, it's it's just it just makes no sense to focus on Though those little tiny things that carve out an advantage and ultimately you run the risk of taking your eye off the really Important thing at that stage and your development which you know for a power lifter is forget weight cuts. We need to get Dramatically substantially massively stronger and we don't even want to think about other distractions until we get there So yeah, you can definitely backfire if you're trying to get too cute with weight-regate weight Manipulations before you're really ready for it for the prime time. Yeah, definitely That is very common conversation that we have with our clients. So I I wanted to jump into Something that I see alarmingly frequently in the cycling world which is Which is how easy is it to Really calculate your total daily energy expenditure because one of the things that I see the cycling world happen frequently I know yeah, you're rolling your eyes Yeah, so I think I have a very expressive face. I didn't even mean to like it's okay I have a hard time not rolling my eyes at some of this stuff too. So one of the things that I see very frequently Somebody puts their stats, you know approximate, you know their weight gender sex in body fat approximately into a BMR calculator and They say okay, great. I've got my BMR. This is how much energy it takes for me to be alive and Then I'm going to look at the kill jewels. I expend on the bike and there's approximately one to one calculation to to KKal and I'm gonna add the two together and that's my nutrition plan so My tongue in cheek question is how accurate is this method? Man, it's just really tough Like one of the reasons that I consider total I'm sorry that I consider W labeled water to be such such a huge deal like I was at a spot in my career where I did not need to be going back and doing a postdoc, you know in order to have Opportunities of kind of re-entering the academic world, but the only reason I got back into to the academic world was because there was an opening in Hermann Ponser's lab and Hermann Ponser, you know has forgotten more about W labeled water than I'll ever learn And so I got back into it because I was like having worked in this space, you know doing research in the space and then working as a practitioner It is just so hard to actually get decent approximations of total daily energy expenditure And I wanted to actually get into this W labeled water
research once and for all. I was like, I just need to get into this method in order to really get at some of the questions I want to answer. So the short answer is it's extremely, extremely difficult to get a decent approximation. One of the things I've found to be reasonably helpful is if you're going to have an extended period of time where you believe that your training load and just kind of overall daily energy expenditure are going to be reasonably stable, right? Whether there's not going to be a dramatic upward or downward trend over a given fixed period of time. So when I say fixed period of time, let's call it somewhere between two and four weeks, for example. What's really nice about that time frame is it actually is feasible to keep things pretty consistent for that period of time. It's also reasonable to assume that you're not going to have dramatic fluctuations in fat free mass. You're not going to be gaining five pounds of muscle or losing five pounds of muscle fingers crossed. That would not be a typical thing. So what I like to do with people is like, if we really are just trying to figure out big picture, I want to get an idea of how many calories my body is burning. I say, let's just commit. Let's do two really stable weeks of good high quality training, keep things relatively flat in terms of how much we expect our expenditure would be from day to day. Let's before and after the beginning and end or throughout that period, let's really diligently track our calorie intake and let's really diligently track our morning weight. So our body weight every morning and standardized close after we've used the restroom. What I like to do then is just crunch the math and say, "Okay, let's look at our weight trend. Let's make the reasonably okay assumption that the slope of that weight trend over this time period represents gains or losses in fat mass or if you want to tweak the ratio, you can do that mathematically." But let's look at, "Okay, so if over, for example, let's make this super easy because no one wants to do live math on a podcast with the cameras roll. I've gotten a very wrong in the podcast before." Well, I've math is such a bad idea. But the general premise of this method is, let's say body weight, we got super lucky. It was completely flat over this two week period and you had pretty constant, pretty consistent habits and training loads and you were able to maintain your body weight at 4,400 calories a day. Then boom, we have a really good basic starting point for you of saying, "Okay, you're, you know, as you go up and down in terms of what you're doing with training, at least you're kind of home base based on what you were doing here was about 4,400 calories a day." Now where it gets a little slightly more computationally intensive is, if you had some gradual weight gain or weight loss during that period and there's basically two different ways you could approach it. One is to actually crunch the numbers using what we call the energy balance method where you say, "Okay, well, if my body weight increased by x pounds during that time and y percentage of that could be reasonably considered fat mass, you basically calculate what was the total net energy gain of my body over this two weeks. Divided by 14, that's your net body energy gain per day." Now you say, "Oh, every day I was in a deficit of 300 calories when I was eating 4,400 calories, so my, my, my kind of total daily energy expenditure estimate would be 4,400 minus 300 is 4,100. Like that's about where I would maintain." So you could crunch the numbers that way or if you don't feel like doing the heavy math, you could basically try again and say, "Oh, interesting. At 4,400 calories I had some gradual weight gain going on. What if I replicated this and instead of 4,400 calories, what if I try to eat 4,000 calories a day and see how that goes?" And so you could kind of choose and you can pick your poison. Do you want to do the math, which a lot of people would avoid like the plague, or do you want to say, "Okay, let's do a little guess and check and see. What does it take for me to actually maintain weight stability over this two week period at a given caloric intake?" And the one thing I want to really highlight here is my preference is to do daily weight measurements because if all you do is a single weigh-in at the beginning and a single one at the end, now you've opened yourself up to considerable error from just like a random, you know, I had a high sodium meal the night before and now my whole equation blew up. So it's really good measure that weight every single day and calculate your slope so that you have a little bit more, a little bit more safety built in to prevent massive impacts of a single day of water weight fluctuation. Yeah, and this is exactly how I tell people to do it and quite honestly, I'd say 60% of the time, they hate it because they're like, "I want to get in a diet right now. Why can't I just run a couple simple math equations and figure out what my energy needs are then subtract 500 from that?" And you mean I've got a waist two to four weeks before I can actually start to like make my way to my goal. Are you kidding me? Yeah, and it's tricky because there are so many, man, you know, at the consumer level, there are so many gadgets that are begging you to believe that they can tell you your energy expenditure either during activity or throughout the day. And I can just tell you right now, none of them are where they need to be in terms of the precision and accuracy where we can feel good about that number. So that's like, like I told you, a doubly labeled water is valid enough that we can feel really good about acting upon that. The only issue is it's very expensive and it's not very accessible. So this energy balance method of doing some quick calculations is kind of our next best option. And yeah, it does take a little time investment, but it is worthwhile and what's really nice about it is if you bite the bullet and do it, it also pays off for what do we do next, right? So you talked about how the example you gave was someone who wants to jump on a diet. Well, I've spent the last decade writing about what happens next, which is you jump on a diet and start losing some weight and your energy expenditure, expenditure changes in response to you being on a diet and losing weight. So even if you say no, I need to hurry and get this number right now. Guess what? In four weeks, it's going to be different. So we need to actually like invest in like saying here's our starting point. Here's what we're going to do as our first adjustment to your caloric intake, but eventually weight loss is going to start slowing down. And if we don't change anything, it'll eventually plateau. And what we learn from doing these calculations allows us to make further adjustments, right? So if we're looking at these slopes and body weight and doing these calculations of saying, well, if I know how many calories you ate during that time period and I see your slope and body weight, now we can start making inferences about, oh, okay, it looks like your total daily energy expenditure when we started was 4,300 calories a day. But right now it's looking more like 4,100 calories a day. So let's go ahead and drop your calories by 200 and get things back on track. So it's valuable to invest in learning the procedure because it's the gift that keeps giving as things start to fluctuate. And just like we said, you know, you can have this perfect baseline number. But guess what? You ramp up your training, it changes. You drop your calorie intake, it changes. You increase your calorie intake. It very well, it very well might change because that's another ramification that people don't necessarily talk about as much. So let's say, you know, your coach and somebody, all this stuff is new to them. It's, you know, they haven't really thought much about it, but you say, well, okay, I've been doing my really high volume training for a long time now. This is my typical routine. I eat 3,400 calories a day. My weight's pretty stable. So that means my total daily energy expenditure is 3,400 calories a day. Well, it is possibly, we've talked about all these different little adaptations and shortcuts of your body kind of constraining things, right? So maybe they're doing that workload and they're maintaining on 3,400 calories per day, but they're also amenoreic super low T3, you know, that their sex hormones are super low. And so maybe you find doing that same volume of activity, you start saying, well, what if we bump you up to 3,600 calories? And they aren't necessarily gaining weight, but now all of a sudden their thyroid hormone is kind of rising back up and that, you know, maybe they just had their first period that they've had in a while. So you can start to see a potential for, as you start working calories back up, you're unraveling some of these shortcuts that are in place and you find, well, we thought that workload X meant that you will burn Y number of calories, but that's just kind of where you stabilized after applying all these different adaptations and shortcuts, you know, physiologically. And we may find that for you to actually, you know, feel and perform your best at that workload, instead of being at 3,400, you should have been at 3,700 all along or 3,800 all along. So yeah, it's really important to take a holistic approach where you're looking at body weight changes, looking at symptom changes. I hate to pathologize it by saying symptoms, but I'm not sure what other word to put on it when you're talking about, you know, hormones that are fluctuating in and out of the reference range. I think it's valuable feedback to kind of contextualize the numbers that you're working with. Yeah, for sure. And I think that you headed off my next question also, which was, which was gonna be like,
you know, could you be weight stable and experiencing a lot of compensation? Because, you know, just, you know, from first principles, I would guess yes. And it sounds like the answer is yes. And it's something I see all the time in cyclists. And, uh, and one of the other things that I, I was thinking about asking, but I was like, uh, we kind of got other stuff to talk about, but I'll, I'll kind of glance on it, which is, um, you know, when people have been under eating for a long time, one of the things I actually see often is that they will, their body weight will start coming up gradually to kind of where they were before they, like, you know, kind of flew the coop on the diet, uh, as it were. And, uh, and it's usually at that point that they actually like look and feel their healthiest again. Even if they're like, man, I feel fat. I was so skinny for so long. Yeah. Yeah. Yeah. There is some really interesting literature on weight regain. Um, and, you know, uh, uh, uh, uh, uh, researcher of the last name Dulu, D-U-L-L-O-O has done a lot of really cool work here of trying to figure out like, what is the kind of order of operations here? So when you take someone who is weight reduced and then you start refeeding them, what happens? Um, and, and like you're alluding to it, it's usually not the case that like the first thing that happens is their energy expenditure spikes because that doesn't really make sense, right? Their, their body has kind of adapted to this underfed state. And in the process of doing so, they probably lost a combination of fat mass and lean mass. And generally what we see is that like early stage, uh, refeeding tends to kind of have this sequential process of like first, you start regaining some of the fat, a little more gradually you start regaining some of the fat free mass. Um, your ravenous appetite usually doesn't chill out until you've regained all the fat free mass that you lost. And gradually throughout that process, we start to see, you know, kind of the reversal of some of these energy constraint mechanisms. Um, and so the exact timeline can be hard to draw out because it, it looks very different for people of different circumstances. So for example, you would never, you would never, I think, assume like two areas where weight gain is commonly discussed is one with like the biggest loser study where people lost like 130 pounds. Um, and basically, you know, went, you know, went from a extremely high BMI to a high BMI, for example. And then you look at the Minnesota starvation experiment where people went from a normal BMI to like literally almost starved, you know, like an average group level average of 5% body fat. You would have to assume that the refeeding time course looks very, very different there and the kind of sequence of events looks very differently. Um, but yeah, all that is to say there's, there's a lot going on in weight regain and refeeding. And I think a lot of it has to do with exactly how extreme was the initial contact. So there's no reason. Like Minnesota starvation study or starvation experiment. It's exactly what it sounds like conscientious objectors. Um, this is back like World War II era where basically, they basically said, okay, you don't have to, you know, go, uh, fight in the war, but you have to do this study. And they starved on like really, I mean, they looked horrible. There's pictures of the subjects. You can look it up. They really took it as far as you could reason. They took it farther than you could reasonably justify. Like, it would happen today. Yeah. Yeah, you, you never do it today. It just couldn't happen. Um, in any case, you know, they got to the point where they were so lean and so, so starved that there were, um, you know, some of the participants experienced psychosis, some of them harm themselves to, you know, either because of the psychosis or to get out of the study. Um, but it was a really extreme instance. And the physiological, uh, circumstances, they were just so different than, you know, going from a BMI of 47 to 33 where you can imagine like if you were in that semi starved position and it's like, okay, we're going to reintroduce calories. There's no reason to believe that the first thing your body would do is start wasting a bunch of energy and say, oh, cool. We don't need any of those adaptations in place. And like, you're going to have to regain some weight before that happens. Yeah. Every time I, uh, I start discussing this with people, I'll, I'll either send them, uh, they, uh, what was it? The title of it. Like they starved so others could eat, uh, the review of the Minnesota, cause the actual, the actual publication is like a book. It's like a home. It's a, it's a two volume, uh, two five, six hundred page book. Yeah. Um, and I, or I send them Eric Helms's, can you stay shredded, which is definitely available to the public. And I, I think both are great resources for cyclists. And, and half the cyclists I talked to who are like, like, especially on the pro level who are, are kind of used to their body weight going up and down. They've already, like, they know about all this stuff already, which is really cool. Yeah. And, but I wanted to, uh, get to the, uh, the two papers that I sent to you and you already touched on one, the, um, the, the, the Arrata study, uh, on the, uh, on Georgie Howe, uh, racing the Tour de France Femme in 2023. Um, but I, I also sent to you another paper from, I got, I think the lead author, the author was boss, Ben Horan. I'll, I'll link them in the show notes, but, um, I, when I first saw the use and I, I, and I thought, this is way, way, way more non-cycling energy expenditure than I would ever expect. Did it look the same to you and just to, uh, just to give some numbers to the people listening. Um, the non-exercise energy expenditures were 1.5 to 2.5 BMR, uh, average 1.8. And the total was like 3.5 to 4.3. And so that was the, the, the welta, which was the Spanish Tour de France basically. So does, you know, 1.5 to 2.5. Sound about right for like non-exercise metabolic rate, uh, on, you know, for extreme energy expenditure. You know, it does seem high. Um, I didn't do my homework to the extent I should have. That's what I'm here for. I'm hearing this paper and I've been told that, but here's one thing I would say is I believe if I'm not mistaken that, um, this paper, and this is something you see a lot, um, non-exercise activity expenditure, uh, whether you're looking at this paper or a variety of other papers. It almost always serves as the like other question mark kind of category. And so what you have to really look into, and this is kind of the extent to which I did my homework and then said, okay, I think I have the answer I need here. And in terms of like facilitating the conversation is in this case, um, obviously they did not measure non-exercise activity thermogenesis because it's exceedingly difficult to do so. So usually what you do is you, you measure other stuff and then you say, well, whatever is not the stuff I measured is non-exercise activity thermogenesis. Right. If you measure total daily energy expenditure, then you just do subtraction. So in this case, um, and correct me if I'm wrong here, it looks like they measured basal metabolic rate, um, well, it says measured slash predictive equation. So I think maybe for some of the people they were not able to directly measure it, is that right? Uh, I, I thought I had it up and I don't. I had the array of paper up, um, but I think that sounds about right. Yeah. So, so basically, you know, I'm looking at their figure one and says BMR measured slash predictive equation. And if the predictive equation has some error, now we've introduced error at the basal metabolic rate level, which if we're going to do this whole process of subtraction also introduces error to the what's left over, right? And then when we look at the exercise energy expenditure, that was based on power output. Um, and one of the things that that we talk about all the time is, you know, we can try to do these kind of crude extrapolations, but at the end of the day, exercise energy expenditure is a metabolic process happening within the body, right? And anytime that we're trying to use some kind of external process or external proxy to kind of approximate calorie expenditure, there is going to be error associated with that as well, right? So like, for example, you'll, you'll hop on a treadmill, for example, and based on the grade and speed you put in, and it'll say, oh, yeah, we'll keep track of how many calories you're burning. But like, you, you don't know enough about me to know what's going on as I'm actually, you know, walking or running those miles, right? And so we do find that in the case of this study, you know, now we're looking at error in the measurement of basal metabolic rate, we're looking at certainly the potential for error at the level of the exercise component of energy expenditure. And so then we are basically doing total daily energy expenditure minus those two things with potential error gives us the resulting equation. So all that is to say, I usually in these papers don't look too carefully at like, is this a legit non-exercise energy expenditure? Because at this point, we're like, what exactly are we looking at here? Right? We've got a number we feel good about for total minus a number with considerable potential for error minus another number with considerable potential for error. And so all that is to say, you know, would I, you know, bank on this non-exercise energy expenditure number definitely not for the reasons that I just mentioned. But what's really interesting, so, you know, I talked a lot earlier about that thurber paper. One of the things that they found was, you know, one thing we didn't even touch on in that kind of walk through.
was I don't even know what they did for the thermic effect of feeding. It's not really listed. I'm sure in the full text it's listed out, but in Figure 1 it doesn't really clarify which bin this is going into. But like I can tell you with the thurber paper, they measured basal metabolic rate. They estimated the thermic effect of feeding to be 10% of calories, which is a totally standard estimate. So there's error there too. It could be 15%, but we always estimate 10. Then they looked at the calories during the run. In this particular in the thurber paper, their estimate was basically that this non-exercise kind of other category essentially shrink. I shouldn't say essentially it did shrink, but it essentially disappeared. In the thurber paper, they basically found BMR was reasonably unaffected. Thermic effect of feeding we should not expect to be majorly affected, nor should we expect the energy cost of the run to be dramatically affected beyond the things that we can pretty easily estimate. What they found was that there was this missing 600 calories on average that seemed to largely just disappear from this neat or other category. All that is to say, I want to reaffirm your bewilderment about what is happening in this other category. The answer is, as you go from paper to paper, this is one of the reasons Herman and I recently drafted up a paper about the constraint energy expenditure model. One of the things we continue needing to put in papers is that it's very difficult for us to tell you is this impacting mostly basal expenditure and mostly non-exercise activity expenditure. It's very difficult because the non-exercise component is so difficult to measure and based on a couple little decisions you make in its estimation, you can end up in a situation where it seems like it disappeared entirely or it seems to be unusually large from paper to paper. That's a major challenge that we see when we try to track down these missing calories. It's really fascinating is based on the more robust measures that we have and feel confident with, we know they're missing. We just don't know. It's hard to say exactly where they're coming from. Yeah. Actually, a paper came out like a week ago or something. It just popped up on my Google Scholar notifications where they looked at not only an ultra-indurance running race where two participants ran like 30 something hours. They also looked at what was the energy expenditure the next day where these two people, of course, reported that they were highly sedentary. The answer was three times BMR on that first rest day. Was their energy expenditure? This is one of the things that fascinated me is the cost of repairing yourself from all this stuff is like, I think most people underestimate it. That's one of the reasons that I think it's great that you headed this off with the qualitative accounting of your energy intake and everything like that because I think that's something that a lot of people in the cycling world are trying to big brain it. I'm no different. I did this one way back in the day. I know exactly how this happens. Yeah. No, yeah. It's really interesting because this is something that, now I'm just like basically on the psychologist couch here talking about all the problems that vexed me in my life, but I just talk through all the problems with, I really want to know where these calories are coming from, both in terms of exercise energy compensation and then metabolic adaptation, which is the same kind of concept that relates more to just the dietary restriction. Being on a diet and having your expenditure drop more than we would predict. I want to know where these calories are coming from. I just laid out for you the myriad reasons why it's really hard to say, oh, we know non-exercise activity thermogenesis dropped because it's just this catch all thing that you can only estimate by making a bunch of assumptions about all the other components. Basel metabolic rate, one of the things that's really challenging is there is in many studies a lack of really good standardization of what are we going to do about the fact that a really crazy endurance, a really crazy exercise about period is going to have residual impacts on your basal metabolic rate that can last into the next day. And so in many cases, we may be again in a situation where we say, no, we measured BMR, we know we're not overestimating it. It's like, yeah, but you're measuring it when you know it's inflated from what happened in the exercise about that ended 11 hours before he measured basal metabolic. It's probably an all day activity. A lot of people are probably wondering, you guys have been talking about this exercise, energy compensation, constraint energy expenditure model for a decade now. What do you mean you don't know exactly where the calories are coming from? Well, these studies are hard to do. It's not like they're popping up every couple days. Doubly labeled water is very expensive and very specialized. It's not like any lab can do it. And then you run into the situation where if we don't have really uniform standardization of what are the pre-testing conditions for getting a good estimate of resting or basal metabolic rate? What are the assumptions we're going to make for the calculation or estimation of non-exercise activity thermogenesis? If we don't have those completely hammered out and agreed upon as a scientific community, we're going to end up in these situations where in this paper, it looks like BMR went up. It looks like BMR went down and in this paper, it looks like neat, increased and in this paper, it looks like neat disappeared entirely. And we're going to run into the situation where we say, listen, we measured total daily energy expenditure and it was not as high as it should have been if all of our assumptions helped that much we know. But then when we start to drill down and say, where did all go? And then you also have to factor in an emerging concept, which is the idea that you could argue that maybe sleeping metabolic rate needs to be handled distinctly from basal metabolic rate. And that some of this could be happening during sleep. But yeah, there's all this uncertainty about exactly where the calories are going. Not because doubly labeled water is the issue in terms of getting the total number, we feel really good about the total number that we're getting. But it's when we try to break that down into the four distinct components that it's just so prohibitively difficult to actually measure them directly, which means you have to estimate them, which means you're making all these decisions and assumptions. And from study to study, those decisions and assumptions vary. So it's the dark matter of energy expenditure. Like we can measure it, but what is it? Yeah, pretty much. That is very much how it feels. It's the missing calories that ends up being like a murder mystery. We're trying to track down who did it and they covered up their tracks really well. It's very difficult to find the signal among the noise when you start breaking down component by component. Eric Trexler, the agatha Christie of energy expenditure. There you go. So we are, we're a little long on time, but I wanted to ask if there was anything that we touched on that you wanted to kind of expand on that we kind of glossed over. Not really. I think just kind of summarizing, you know, we through the work that we and others have done with with doubly labeled water, we feel very confident that human energy expenditure is dynamic and adaptable, which means when you dramatically change your exercise habits, when you dramatically change your nutrition habits, it's not, you're not in pure control as you think there's going to be some adjustments that happen, some adaptations that happen. And they really have to be considered when you're making longitudinal plans for what you're going to do in terms of weight regulation, energy expenditure, how your calorie targets are going to change. It's really important to consider. So we know that these things are changing. Our current big obstacle is figuring out exactly what component seem to be changing or what multiple components seem to be changing. But the takeaway is, you know, when you decide you want to lose weight and you cut your dietary calories dramatically, there's going to be some adaptation that shrinks your caloric deficit, you're not going to lose weight as quickly as you planned. If you think you're going to dramatically lose weight by increasing your exercise volume, same thing happens. That energy deficit will be shrunk via adaptive mechanisms and the converse is true. You know, if you decide, hey, I'm going to gain a bunch of weight by increasing my caloric intake. There's a lot of folks who tend to be pretty resistant to weight gain as well. So half of the track sprinters I know are like, man, I just can't eat enough. Yep. And so there's a really cool controlled study, like very tightly controlled weight gain study over eight weeks. I think it was where they basically fed, they overfed everybody the same amount. And they said, like, we're going to calculate your energy needs very, very precisely. We're going to literally give you the food and watch you eat it for eight weeks. And what they found was some people gained like a kilogram or two. Some people gained like seven kilograms over that period. And what seemed to be the biggest predictor was who had an adaptive increase in energy expenditure that ultimately shrunk the caloric surplus that was being introduced. So the take on point is energy expenditure is malleable. And while that
can seem frustrating when we're trying to plan out everything and we're all control freaks with our sport and diet stuff. We want to pretend that we're fully in control. It can be frustrating, but from an evolutionary perspective, it probably saved our life more than a few times. So we kind of have to take the good with the bad and we got a role with the punches and adapt with the adaptation. And I'm going to add in one more practical takeaway, which is for cyclists, especially on the lean mass aspect when you are trying to lose weight, please touch a barbell or a dumbbell. Just do some weight lifting because you can back me up on this, but the loss of a lean mass really predicts the rebound. Yes, that is true. The best predictor we have of weight regain after a weight lost diet is how much fat free mass that you lost. And like you said, it doesn't have to be, you can pick what you want to do. Touch a barbell, a dumbbell, a machine, a resistance band, but any kind of resistance that you can apply is going to be a lot better than nothing. Yeah, for sure. All right. Where can people find you? Well, besides in the lab, Henry and Limer P. Yeah. So you can find me on Instagram. My handle is @trexlerfitness. You can find me at massresearchreview.com. And I currently host two podcasts. One is called Iron Culture. The other one is called Front Page Fitness. They're very different flavors, but all focused on science and fitness and the intersection between them. So you can find those podcasts pretty much anywhere that you get this one, I would imagine. And I am also a lifetime mass subscriber. And the only thing I'm trying to not read right now is the replication crisis article because I'm about to do a podcast on that one. I don't want to be influenced yet. Okay. Who you doing it with? Probably my usual co-host, Rory, who is a PhD in evolutionary or like evolution of life. And Kyle, who is a NASA physicist and somebody I've coached on the bike for a long time. And he's he kicked my ass on the bike in like 2014 in a race and we've been friends ever since. All right. Well, good luck. But I hope you're able to keep it optimistic and joyful because replication crises tend to knock that out of you. All right, everyone. Thank you for listening to the podcast. That was my interview with Eric Trexler. And I want to thank him again for coming on. I know he's very, very busy. He makes a ton of media. He writes a ton of articles and very happy that he was able to come on and answer all of my questions because frankly, I probably could have done most of that episode by myself or talking to Kyle or something like that. But I don't think I would have given a nearly the amount of nuance that he's able to deliver. And he's also of course, eyeballs deep in the research on this stuff. And of course, I am compared to him somewhat of a dilatant. And so I was very happy to have him answer all of our questions and really kind of go in depth with a lot of that stuff. So thanks again to Eric Trexler. And thank you for listening. If you'd like to reach out for coaching with me or our any of our empirical cycling coaches. And you can check out the results that we've had, etc, etc. And if you want to consult with us, that's also a good place to reach out. If you want to keep coaching yourself, we're here to give you the tools to plan and adjust your own training. If you want to check us out on Instagram, go ahead over there if you want to ask a question for the podcast also up on the podcast page up on the top. And I think that's it. Oh yeah, give us a nice rating and a review wherever you listen to podcasts. And yeah, we will see you all next time.
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