Written by Christopher Kelly
April 23, 2015
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Christopher: Hello and welcome to the Nourish Balance Thrive Podcast. My name is Christopher Kelly. Today, I'm joined by Dr. Tommy Wood. Hi, Tommy.
Tommy: Hi.
Christopher: Tommy, why don't you tell us a bit about yourself? I know you've been on our podcast once before and then also twice before on the Paleo Baby Podcast. If you haven't discovered the Paleo Baby Podcast yet, head over to iTunes and just search for Paleo Baby and you'll find us right away. Tommy gave us a fantastic discussion and research led thinking for a number of really interesting topics, if you have kids, things like vaccines and cot death, all sorts of really controversial and interesting stuff. Check that out, the Paleo Baby Podcast. Today, we're going to talk about hydration. Sorry, that's a roundabout way of asking you to just introduce yourself, Tommy, please.
Tommy: Yes, sure. So, I guess, the interesting things about me start with a degree in Biochemistry first. And then I went to medical school at Oxford and graduated a couple of years ago. At the moment, I'm doing a Ph.D. in neonatal baby brain metabolisms that kind of leads on to the stuff we talked about in your other podcast. But throughout my time at university, I rowed a boat, Oxford and Cambridge, and that was my first foray really into exercise, having been quite sedentary as a kid.
But then from there, I started to do more coaching and reading and after a while I did a lot of sort of endurance type races, ultra marathons and things like that. So I've done a whole sort of gamut of different types of exercise and sort of coached athletes through that. And I do some sort of coaching and advising in my spare time from my Ph.D. on various different things. That's kind of like a potted history of what I'd been up to.
Christopher: You're quite unique individual. I think a lot of people listening won't know that not only Oxford and Cambridge the most prestigious academic institutions in the UK, they also are well famous for their rowing and it's an extremely famous boat race that even I still know when it is each year. That's super cool.
Tommy: I was never that good, so I trained with -- I did train with as a sort of the development squad, both universities. But if you sort of -- I turned up with almost no exercise experience, real exercise experience. I've done a couple of half marathons or something when I was about 18. But if you turn up and then all the other guys who rowed Oxford and Cambride, most of them, they've come from Olympic boats. So these are world class athletes.
I was given a go because I was big and fairly strong but, I mean, I barely knew how to put my oar in the water compared to those guys. I gave it a good go. It was great. I sat on the boat with Olympic athletes, which is a huge honor. But they probably wondered what on earth I was doing there.
Christopher: That's interesting and funny. Today, I wanted to talk to you about hydration. As always, the topic of conversation is led by my own personal interest, which is somewhat selfish but I'm hoping that -- We just mentioned this before we came on air that if I reach out to enough people then I'm sure that some others are having the same sort of concerns or noticing the same things. So specifically with hydration, I guess this is quite topical now. Certainly, in California, I'm looking at the window right now and it's beautiful, sunshine, and it's definitely warming up. It's probably going to be quite warm today.
The winter is long since gone. It's getting hot. And the boat race has started. So hydration is definitely something that's going to be on everybody's mind. Probably the rest of the world or some parts of the US are thinking you should dive right now because they're still under now. That's how is, I believe, even nice weather in the UK as well at the moment. I think our timing is good with this one. I'll tell you why I got interested in this.
Back when I first started bike racing and I was a little bit clueless and I thought everything was about making the bike as light as possible, so that's what I did in mountain biking which is not very useful. But the one thing I couldn't really make any lighter was the amount of water that I carried.
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I was sure from what I'd been told and read around the internet or wherever else I'd heard this information that hydration was critically important and there's no way that you should ever attempt to even go out and train without having enough fluid. And enough fluid wasn't as much as you might guess it would be. It was some rule like you have to hydrate a certain amount per hour. So I found myself doing this bike races and training as well, riding around with this enormous CamelBak on my back, which contains 6% carbohydrate solution with maltodextrin in it or something.
And it was a huge disadvantage not only having that CamelBak on my back sort of covered an area that then couldn't let the heat escape, but also some of my races, they start with an enormous climb, like a 3,000 foot climb. So if you're going to carry two liters or even more of water or fluid up that climb, that's quite a lot of extra energy or power just to shift that weight. There's that concern too. So what happened was as I switched to a lower carbohydrate high fat diet, I noticed that I became less and less thirsty.
And then there was one switch in particular that really was a pivotal moment. And that was switching to a product called UCAN SuperStarch. UCAN SuperStarch is a very slow release carbohydrate source that claims not to spike insulin in quite the same way as a simple carbohydrate would. And I noticed an immediate change in my thirst, like I just wasn't really thirsty at all. And I'm not the only one to notice this. I've spoken to several other people and they've said exactly the same thing.
From there, I got more into reading Tim Noakes' work who has written a brilliant book which I will link to. And I've totally forgotten the name of it. It's called Waterlogged. Waterlogged, that's it. He talks about the problem of over hydration in endurance exercise. That really got me thinking. And now I'm wondering is the whole world wrong apart from Tim Noakes and a handful of other people?
Tommy: That seems to be the case on a number of topics.
Christopher: I know, yeah. I mean, to be fair, he has done at least one spectacular u-turn with the carbohydrates himself. Yeah, I guess, anybody can be wrong. Tell me what you think about this stuff then. Do you think -- I guess, the history, I think, is relevant. Back in the day, and Tim Noakes covers this in his book, that people used to do marathons and they wouldn't really carry any fluid at all. They would just do it and they get dehydrated and then they would drink and they would rehydrate.
That seems to be the way that humans were designed to work. We deviated from that and it's not sure that that was -- It's not clear that that was the right decision. What do you think? Do you think people should just follow their thirst?
Tommy: Yeah. I think that's where we're coming to now. Like you say, back in maybe 100 years ago, 60 years ago, up until about World War II, people sort of said during bike races, marathons, the Tour de France, it was considered ungentlemanly to drink too much water because it was a sign of weakness. I know it's the same in marathons. They encourage people not really to drink during marathon running. And then in the '60s, you have the development of Gatorade by Robert Cade at the University of Florida because he felt that--
I think he did one study where he made people walk and run for around seven miles and saw if he gave them a carbohydrate drink that their performance would improve and he thought that that would be particularly relevant to football players in the final quarter of a football game. And then some people did some studies in marathon runners in the late '60s and they found that people who lost more than 3% of body weight or more than two kilos had an increase in core temperature after the end of the marathon.
And at that point, they assumed that that was a bad thing. I think we can come back to the measures that people use in these studies and whether they're actually useful or not. But then the thing that Tim Noakes really talks about are the dangers of over hydration, particularly points to this period in US military history back in the '80s where they adopted something called water as a tactical weapon, which is basically we were going to be so on top of hydration that we sort of drink ahead of thirst and make sure you're over hydrated.
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These guys were drinking almost half a gallon of water per hour. And then what happened is during a ten-year period, I think it was five or six guys died from something called hyponatremia, which basically is too little salt in the blood, too little sodium in the blood. And this actually has become -- There was a famous case in the early 2000s of somebody who died in the Boston marathon. It's literally just from drinking too much water. The sodium in the blood goes too low.
And to start with, you get things like changes in cognition or changes in mood and then eventually you can have seizures. And if you get really bad, the brain will swell so much. It essentially what happens, the brain swells so much that it sort of pushes itself down, tries to push itself down to the bottom of your skull then you basically end up -- And it kills you. That's where the real danger from over hydration comes from.
Again, he references a guy called Bernd Heinrich, who is a biology professor emeritus at the University of Vermont who talks about the fact that we as a species evolved on the plains of Africa. And we spent many hours a day hunting. And we are uniquely adapted to actually become dehydrated, voluntarily dehydrated and to choose to not drink because it may affect our abilities to hunt and then catch up later.
And we sweat, which almost no other animals do. So that means that we can regulate our body temperate very easily in another way. And there are many tribes in Africa that will hunt 20 miles in a day, in the middle of the day, while the predators are hiding in the sun or hiding in the shade, they can go out and hunt prey and they won't take any water with them. So we have the ability to become dehydrated and still perform a fairly good level. And there are lots of studies now coming out that we can talk about that sort of suggest this.
And it really seems to be that if we drink just for thirst both in studies and just from day to day people going about their daily activities or daily exercise, then that absolutely seems to be enough to keep us hydrated and healthy. So there doesn't really, even though if you exercise and you become dehydrated or you lose a certain amount of body water -- For instance, I sweat a lot. I can easily lose two or three kilos in an hour, if I'm doing some kind of marathon in the heat.
But if you drink to thirst, you won't completely compensate. You won't drink your way all the way up back to your weight but you get about maybe 50% or 60% on the way there. And in terms of performance, that seems to be enough.
Christopher: Okay. Is it useful to talk about where thirst even comes from, the sense of thirst even comes from in the first place? Can it be relied on?
Tommy: So, again, if you go back 20 or 30 years, they thought that it couldn't be relied on. And that was because when you're looking at studies of hydration and performance, some of the first studies where they were looking at the amount, what they first looked at the amount of body weight you lost. And it was always assumed that whatever body weight you lost was water. So then if you just relied on thirst you wouldn't drink yourself up back to your normal body weight.
They thought that if you're looking at body weight as a function of how much water you lose, then obviously, thirst isn't doing a good enough job because it's not getting you back up to that original point. And thirst basically comes from -- So the instinct thing is that none of the things that they measure are all addressed to in these studies are actually what the body regulates in terms of thirst and hydration.
So they look at things like plasma volume, which is basically the volume of the blood minus the cells or something like body weight. But what the body actually does is it looks at the total amount of stuff, so solid and that's all the minerals and all the other things that your blood carries. And it looks at the total concentration of those. So it's something called the plasma osmolality and that's measured by the hypothalamus.
And as that starts to go up, that means that all the stuff in your blood isn't diluted and there's much water, so then that stimulates thirst. And that's quite highly regulated. But when people have tried to dehydrate people and then see how they perform, they don't -- They're not dehydrating by certain amount of plasma osmolality and then seeing what happens. They're going for surrogate measures that maybe isn't as useful and they're making assumptions and they make their conclusions of a study less relevant.
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Christopher: Okay. So I've got this quote here, which I thought was interesting. I think I got this from -- Let me just double check before I lampoon someone. It's from the Osmo Nutrition website. This quote comes from somebody, Dr. Sims, who I believe has a Ph.D. of some type. She's obviously a very smart woman. But let me see what you think about this: The science is simple. Hydration, which first refers to the maintenance of water in your blood, is critical to maximizing power, endurance and reducing fatigue. When you're thirsty, you've already lost 2% of your body water and 11% of your power.
So, 11%. That's far more than makes the difference between first and tenth place in any sort of elite event of any type I can think of. So it's huge. If this woman is right then the hydration really is important. But she says the science is simple. So do you think -- What does the evidence show? Is that true?
Tommy: Actually, nowadays, what they're saying is that as long as you -- Sort of like the American College of Sports Medicine has like a mission or position statement on hydration and they say that as long as you drink to keep yourself above 2% of body weight -- Again, that's still the measure they're using then. Then you're probably okay. And that's enough. And actually, what they've shown and we've known for a long time is that you can actually lose about 2% of your body weight and see no difference in performance.
And there's about 2% buffer there. So that what she's saying isn't actually correct because once you -- You might even need to go quite far below 2% before you actually start to see, in the real, in the world performance studies, before you actually see a decrease in power, particularly so, I mean, one of the best studies is one that we've discussed before, which is done a couple of years ago where basically they took some scientists.
Some scientists took some cyclists and these cyclists were dehydrated by 3% of body weight which is where they thought they'd see a decrease in power or time trial speed. When they did that, so they get them to walk and cycle a low kind of pace in 33 degrees, that's about 95% Fahrenheit, something like that, for a couple of hours. And then what they did is they rehydrated them intravenously so they gave them a saline solution into the blood. But they were blinded.
So they didn't know how much of their body weight they were getting back. They were dehydrated by 3% and then they were either kept at 3%, taken up to 2%, dehydrated by body weight or filled back all the way. And what they actually found is that between those three treatments, there was no difference in performance. And so what that points to is all the problems that we've had in other studies of hydration.
So things they did like the average or the old studies looking at dehydration and performance, you dehydrate the person initially, which obviously isn't something that the average athlete or any elite athlete would do. You'd start in a hydrated state and then you might become dehydrated during the event. But you never start in a dehydrated position. And they do something. They might give you some diuretic, so some drugs that make you pee out extra fluid. Or they'll make you exercise first.
But if you exercise first, then obviously you've lost glycogen, so then you have less energy reserve for the exercise you're about to do, so that's going to affect your performance as well. And they're usually done inside, so there's no wind or anything like that. But the most important thing is if you spent however long it is now, 50 years, telling people that being dehydrated is going to affect their performance, and then these athletes or just average people or really athletes are in the lab being tested and they know they've been dehydrated already, immediately they're going to think, "I'm thirsty. I'm tired. I'm dehydrated. I'm supposed to perform worse because I know I perform worse when I'm dehydrated." And already you biased the study.
Christopher: Right. I wonder whether I've seen the opposite of this. After I read Waterlogged, I changed my behavior based on my respect for Tim Noakes. And it's not clear to me whether I was never thirsty in the first place or whether I became less thirsty after reading the book.
Tommy: So, I mean, I have a few theories about that because you sort of become ketone fat-adopted and I have some theories about why that might reduce the amount of water or it might reduce your thirst, which we can talk about later.
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But the -- What was I going to say? Potentially, one of the things that might have happened over the last few years is you become a better cyclist. You know that in elite athletes, they tolerate dehydration much better. And they tolerate thirst much better. And thirst doesn't have too much of an effect on their performance. Because, I mean, when you're thirsty, it's very difficult to think about anything else. But if you're used to that and you've trained in that position, those study of Kenyan runners that was run by Tim Noakes' team, which showed that when they're running and training, they don't really drink anything.
So they're used to dehydrating themselves and then rehydrating later. And so elite athletes tolerate dehydration better. But also, if you take somebody who's even not an elite athlete and you get them used to the protocol of dehydration, so that one study which was done -- I think it was just last year and they dehydrated people by getting them to run for 45 minutes and then do a five kilometer time trial on the treadmill. And if they were just dehydrated then the time trial, they're about 70 something seconds slower than they would have been if they were probably hydrated.
But if they did the time trial having gone through the dehydration protocol four times a race, so they were used to the feeling of being dehydrated. Then there was no decrease in their performance. So there's a huge cognitive part of it as well. So if you are used to the dehydration and your body is acclimated to it, then actually that might be part of the reason why you see less of an issue, is the fact that your body is used to working in that state. And then, obviously, if you get to carry less water and then you move faster and you feel better because you've got better performance, and all that stuff can feed into it as well.
Christopher: Right. Absolutely. And you can see this. When I ride with Julie, who she doesn't ride very much, I think another thing that comes into this is the ability to sweat, which I understand is actually trainable. So as you get used to being hot and maybe performing, doing exercise in the heat, then your ability to lose heat through sweating gets better. And so Julie has almost no ability -- I'm sure there's a genetic component to this too.
But she has almost no ability to sweat at all. So once she gets hot, she just gets really flustered and almost slightly panicky. If you look really closely, you can just see tiny little beads of sweat in her forehead. But basically, she's not sweating at all. Whereas, I don't think of myself as a sweaty person. But if you put me in the sauna for ten minutes, I'll literally -- It's like water is pouring out of me from somewhere. And I'm sure I wasn't like that before I started training. This is something I've acquired.
But it all amounts to this kind of just the stress signal that's coming to some unconscious part of the brain. So Julie is just thinking, "I'm hot. I'm exhausted. I can't breathe very well. Make this stop. Give me that water. I need to cool down." And it's something that we associate with cooling down and maybe removing some sort of stressor. So to have that like removed from you forcibly, "No, you can't have any water." It's just going to make the situation worse.
Tommy: No, absolutely. And it's meant to be like that. If you're, so say, we go back to the sort of evolutionary perspective and you'd been out hunting and running in the heat and you suddenly become exceptionally thirsty, what that's going to do is it's going force you to slow down and conserve energy until you manage to find some water and then you can continue again. So thirst is that kind of driver and the discomfort from it is the driver to kind of -- It's like a self-preservation. I mean, that's exactly why it's developed.
And absolutely the more people train, the more they seem to sweat. But an interesting thing, I think, is that what they've seen in a number of studies particularly in long endurance or marathon, ultra marathon, Iron Man type races, the people who finish fastest tend to finish with the highest body temperature and the most level of dehydration. So you know they'll lose almost 10% of their body weight. And a lot of that isn't water. A lot of that is [0:24:36] [Indiscernible] glycogen and then you lose water associated with that.
Or if you want it, you can gain water and it comes into your circulation. But this people, if you increase your core temperature, then that allows you to offload more temperature without sweating, so just increase the gradient to the environment. So actually, by running faster, and it's actually just the running faster, which increases your metabolism, which increases your temperature. Or running or swimming or whatever.
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Then actually, if you get used to that and you adapt to it, then actually you'll offload more heat that way without sort of on the side of sweating as well. So that kind of entrained the people that that's another adaptive mechanism that allows them to offload heat and preserve water if they need to. But again, they're much better at dealing with that level of dehydration.
Christopher: Okay, I understand. And I wanted to get into -- So where does this that the sugar thing fit into all this? That interests me. It seems like sugar stimulates my thirst. I've noticed this now. I did a bike race, I think it was late last year, and I was feeling terrible. I think there was just something else wrong with me. I don't know what it was. I was having a really bad race. And I thought maybe I should just take some sugar, this high fat ketogenic thing. Maybe this doesn't work for this. Let's just do the sugar.
There's an aid station every ten miles and the course is stocked up to the nines with all the different types of gel and I just thought, "All right, screw it. I'm going to take one." And all it really did was made me thirsty. I still felt awful. It made me really thirsty which really sucked.
Tommy: Yeah. I mean, so this is another point that I had was that all these studies, particularly looking at the sports drinks and a lot of these studies that have come out over the years, the stuff that I'm talking about is the stuff that's on the fringes because you can go and you can find hundreds of studies showing that this amount of carbohydrate plus this amount of salt will increase performance as much. And guess what, that's Powerade or Glucose Aid if you're in the UK.
But all these studies are done in carbohydrate adapted athletes. So this is something they're used to and they're used to using that amount of glucose. And so then, I think, applying that to a keto or fat-adapted athlete in terms of requirements for both electrolytes and energy is probably not that relevant and might actually be something completely different. But what I would think is that if you have -- So the problem is, if you're generally fat-adapted, you become peripherally, your body and your muscles in general become more insulin resistant.
And that saves the glucose that you do have for the brain. And obviously, when you're exercising, you have some non-insulin dependent glucose taken to muscles. So that kind of bypasses the system but you'll still get less glucose into the muscles than you would otherwise.
Christopher: Let me stop you right there. Sorry to interrupt you. How do you know this for sure? It's something that almost interests me. It makes perfect sense what you just said. Your brain would try and preserve glucose for itself. But I'm not sure I've really seen any really good evidence that shows that's true. I recently listened to it, I don't know if you listened to it, but it was Peter Attia talking on Tim Ferriss' Podcast. I think it's episode number 65.
It's the second one he did where he talked about going into seeing some guy at Stanford and they did some sort of weird glycemic clamp on him where they basically injected glucose and enough insulin to cover it in the hope of trying to measure how sensitive to insulin he was in his state of ketosis. And I think I'm getting this right, repeating this correctly. But what they found was he was incredibly sensitive to insulin and the amount of insulin they gave him to cover the glucose that was going in was actually far too much.
And he ended up nearly going into a coma. It was a really, really ugly ending. He gave that one example. And then he gave another example where what you've said is exactly true. Like somebody failed an oral glucose tolerance test and, therefore, was unable to donate a kidney to the brother. A kind of crazy story but his advice, Peter Attia's advice, to the guy was just eat some carbs for a week and try the test again. And sure enough, it was fine. So both sides of the evidence [0:29:23] [Indiscernible] even though it's anecdotal, but have you seen something that shows that this is true for most people?
Tommy: Yeah. I mean, I'm certain that it's very individual. And the problem is that, one, it's very difficult to measure insulin resistance, and doing something like euglycemic or euglycemic clamp where you try and keep glucose the same and see how much insulin you need, given how much glucose to try and clear it. And so there's not many studies where they've done a lot of that in a lot of people because it's difficult to do. But there are studies where you -- And they're mainly done in the metabolically deranged.
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I guess that's part of the confounder is these people have type II diabetes or obesity. And they've put on -- And it's usually maybe two or three weeks, maybe a bit longer, of a low carb high fat diet. And then you do an all glucose tolerance test, which is obviously as sensitive. And what you see is that glucose goes sky high and then it takes a really long time to come down. Somebody like Peter Attia, I mean, he's a pretty big guy. So he's got a lot of muscle mass, which might have maintained as insulin sensitive. He does a lot of sort of high intensity exercise and weight training, as far I remember right.
Christopher: Yeah. So this hypothesis is exactly that, I should say. I missed the part of the story, that was his hypothesis is the exercise is kind of the key factor here. And if you're in a constantly glycogen depleted state because you've been exercising without taking on any carbohydrates, then that might stop you from entering into this peripheral insulin resistant state. And it's certainly true for me. Obviously, I haven't done the fancy euglycemic clamp test at Stanford but I've had literally one or two days since I went into ketosis probably 18 months ago, where I've eaten like, "Screw it. I'm just eating a dessert. Let's just do this."
And then I checked my blood glucose and 30 minutes later, an hour later and it goes up into the 90s. And then the next morning, like my fasted glucose is 85 again. There's no real -- I mean, I guess, what's happening with your blood glucose doesn't really tell you how insulin resistant you are. But it certainly didn't do anything crazy like you might expect.
Tommy: I mean, your body will always find a way to clear it. But it's not to do with how necessarily high, how high it goes or how long it takes to clear it and all that kind of stuff. But maybe, so say, you're in a race and you have a load of glucose and actually you're not necessarily that insulin resistant and you've been exercising your muscles so you have a load of non-insulin dependent glucose uptake anyway into the muscles.
But what will happen is insulin will go up and very transiently your serum osmolality will go up because all that glucose will hit your system and acts like a solute in your blood until it's cleared, however long that takes. So, I think, the combination of those two things, because insulin causes you obviously to retain more sodium, so your sodium will increase transiently, your glucose will increase transiently and that, in medium to short term, maybe however long it was, ten, 20 minutes, half an hour. I think that's probably what made you more thirsty.
Christopher: Okay. The pennies just dropped here. So this happens in the late stages of diabetes. If someone gets really, really thirsty, is that what's happening there? There's so much glucose, so much solute in the blood like your brain thinks you're really dehydrated and makes you really thirsty.
Tommy: It's partly that but it's also -- So that's absolutely it. Your osmolality has gone up and that makes you thirsty. There's also the fact that what happens is your blood glucose goes up so high that you basically overwhelm your kidney's ability to re-absorb glucose. So what happens in the kidney is sort of basically everything goes through a basic filter. And all the small stuff, which is usually like amino acids and glucose and sodium and all that stuff is reabsorbed later on. And then what's not reabsorbed is peed out.
But the kidney can only reabsorb so much glucose. So if you've got more glucose in there in the blood, you'll pee that out. But what it will also do is it will draw fluid out. So it will basically -- It acts as a diuretic and so those people pee a lot more as well.
Christopher: Okay. Yes, I talked to this guy. He phoned me up for a consultation. And that was how he found out that he had diabetes. He was just out on a hike once. I mean, he knew that he'd always been weirdly thirsty. And he was drinking at that time a gallon of orange juice per day. And yeah, he was out on a hike one day. He just got overwhelmed with thirst and ended up drinking out of dirty puddles because he was just so thirsty.
And he went to the emergency room afterwards and that's when they found out. Yeah, scary stuff. Something to us or lesser degree is happening there when you take on sugar. So are these people crooks then? I want to go back to what that woman just said. It's like, okay, well, if I feed you this sugar, then you'll also need more drink. [0:34:52] [Indiscernible] ice cream salesman on a hot day. It's almost like the ice cream salesman that somehow got the ability to manipulate the weather and make it really hot so everybody wants his ice cream.
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Tommy: Yeah. Obviously, there's a lot of -- And the people, the groups of people that think that we should, we don't necessarily need all these fancy drinks. I mean, you just drink water to thirst and maybe we need a small amount of electrolyte replacement, but probably not that much. There's always the conspiracy theory that the drinks conglomerate have kind of forced us in this direction. Obviously, all the advertising associated with that and people, loads of adverts and athletes saying that drink this to stop getting dehydrated.
I mean, there's certainly an element of that. But I also think that, at least up to a certain point, these people think that -- I like to think the best in people. So there's certainly an element where they're certain based on the studies they've read. And there were a lot of studies which show that drinking whatever it is will make you run faster or preventing dehydration or make you run faster. But obviously, the problems, you kind of mention all the problems with a lot of those studies.
So they honestly think that they are helping people and reducing things like claps and dehydration and helping people perform better. So I think it's kind of a bit of both.
Christopher: Okay. And then what do you think about the recommendation for electrolyte. I've had quite a few people saying to me, "It's okay if you just drink plain water. But you've got get your electrolytes." What are your thoughts on that?
Tommy: Yes. I think it's tricky to give sort of broad spectrum recommendations because it really depends on how much you sweat and the kind of person, how much solid, the minerals that you lose. Most people, your sweat is mostly water. And you'll lose more water compared to the amount of salt that you lose, say from your sweat. So that's why the concentration of the blood tends to go up as you preferentially lose water.
But they've shown, in terms of rehydrating people, they've shown something like two -- They always say, it's always like 2% to 6% glucose. And they have that as an energy source rather than rehydration or rather than a rehydration source because what happens is the glucose gets. So what you need in order to keep the fluid that you drink in the blood, you need to have something that will keep it in the vascular system, so in your blood vessels.
So if I took you and I infuse a load of water into your vein, most of that water would leave your blood and end up somewhere else. So it would probably -- You'd probably end up with swollen feet or something like that because the water, the concentration of the fluid that's outside the blood vessel is higher and it would draw that water out of your blood vessel, our of your plasma volume.
So what you need is you need to give something that will keep it there. Glucose is metabolized very quickly so then once that glucose is metabolized then again you'd left with just water, which will go somewhere else. So you need something like sodium, which will keep it in -- The sodium gets absorbed and you get more sodium inside the blood and that will keep some of the water there. Because water basically flows from where things are less concentrated to where they're more concentrated in terms of all the other stuff that's dissolved in the water.
So even very dilute amounts of sodium, like saline solution that you give a patient to rehydrate them is an 0.9% sodium chloride. So that's about two teaspoons of salt in a liter. But even something that's like a fifth of that in terms of the amount of salt in a liter of water, that kind of concentration of salt seems to be enough to get people's, to rehydrate them compared to something like water. So you really don't actually need that much, if you see what I mean to stay on top of your hydration.
And again, like if we go back to earlier, if you're somebody that trains a lot and it gets used to it, then you can actually deal with a reasonable amount of loss of both water and some electrolytes in your sweat without any real problem.
Christopher: So this is more about -- Obviously, some salt is lost in the sweat. So when you take on electrolytes with that fluid, this is not really about replacing the salt that's lost in the sweat. It's more about trying to make the fluid that you do take more effective to make it stick inside the cells, is that right?
[0:39:59]
Tommy: Yeah. Well, to make it stick inside the blood.
Christopher: Inside the blood.
Tommy: Because if you drink just pure water, it will go everywhere, which is not necessarily a bad thing. Because when you exercise, more fluid goes to those sort of will naturally leave the blood and go to those muscles because of the way they're exercising and the movement of the things like potassium and calcium inside and outside the muscles. You need some more fluid there. So almost half of, if you measure, the plasma volume of somebody, when they've exercised to dehydrate themselves.
Most of that fluid will actually -- It hasn't gone anywhere except for it's gone to the muscles and then it will come back into the circulation. So when you measure the volume of the circulation of somebody, they've actually just redirected that fluid to the muscles and then it will just come back when they don't need it for exercise anymore.
Christopher: Interesting. That is interesting.
Tommy: So when these people look at plasma volume during exercise, they assume that plasma volume is dropped, which is a bad thing. But actually, that plasma volume is just -- That fluid has just gone where the body needs it. And once they stop exercising, it just comes right back into the blood.
Christopher: That's really interesting.
Tommy: So it's a combination of replacing the salt and then -- Replacing the salt lost and also just having the salt go and stay in the blood, if you see what I mean, because the two kind of go together.
Christopher: Okay. And then what conclusion do you make when you see someone that's a really salty sweater? So there definitely seems to be a difference between people like I get a little bit, like my helmet strap is just like maybe a tiny bit salt visible. But some people you see, they finish their bike race, and maybe what I'm really noticing is the difference in color of people's spandex or something.
Tommy: Those tied lines.
Christopher: Exactly. It's crazy. You see some people are like, "Holy cow, that's ridiculous." It's literally crusting and flaking off of them. What conclusion, if anything, do you make when you see that?
Tommy: I mean, I don't really think that -- As far as I've seen and it might just been that I haven't seen any data on this, I don't really think that you can make that much of a -- Whether there's much of a conclusion to be made there. And I think that's just some personal, just whatever your body needs to shift to get the kind of -- Because all the body is trying to do is maintain homeostasis, which is basically keeping everything nice and regular. It doesn't like being out of its comfort zone in terms of physiological stuff.
So it's basically whatever it needs to do in order to maintain that and keep you alive, it's what it does. I'm not sure that somebody with saltier [0:42:54] [Indiscernible] at the end of their bike race is, if there's anything we can particularly get from that. But you can kind of -- I mean, another thing -- And again, this is one of Tim Noakes' things. He's done studies on this looking at levels of salt in the blood and things like cramp.
And they see that actually the amount of salt that you lose doesn't -- Or you will lose some. That doesn't really correlate with cramps or anything like that. So we're told that potassium or magnesium or sodium and whether you're dehydrated or not, is associated with cramps during races, particularly again, long races where you get dehydrated. And he's found there's actually really no correlation between that and between the amount of sodium or the amount of minerals you lose and cramping either.
Christopher: I'm so glad you brought this up because -- Somebody would probably kill me if I didn't mention this because cramp -- And I'm really annoying, well in a number of ways, but this is one of them. And that's like I don't know what cramp is. I've never experienced cramp. I've seen people cramp in a bike race and so I have an idea of what they're going through. But I've never experienced it. And so it's not something I think about a lot.
And I probably wouldn't have asked you because of that. Yeah, of course, it's something that is like pro science or conventional wisdom, whatever you want to call it, cramping is somehow related to dehydration or electrolyte balance. So you think all that is not true then?
Tommy: Well, I mean, just based on the -- So, I guess, just based on, say, this is one particular study from Tim Noakes' guys, I mean, this is about ten years ago now, and they looked at cramp in people in ultra distance marathon. And in those that cramped, they had slightly lower sodium but it was completely within the normal range. They had higher, slightly higher magnesium but again completely in the normal range.
[0:45:01]
Like potassium wasn't any different. And these were all the things that we're told are associated with cramp. And actually, in the group of people that didn't cramp or didn't have any history of cramp, at the end of the race, they had lost their concentration of their blood. Their plasma osmolality had gone up more and they'd lost more weight. So they were more dehydrated and they didn't get cramps. So there's actually, at least in that study, there was no association between any of those things and cramp. And that seems to be a very individual thing.
And because if you look at -- So if you have big changes in a number of, of any of those minerals so magnesium, calcium, sodium, potassium, you can get contractions of the muscles that you can't release because you need like the normal signaling for the muscles to release and relax. But that tends to happen -- And this is the point they're making that paper. That tends to happen in all the muscles in the body or in large numbers of muscles in the body.
But what happens normally if you cramp, you usually cramp in one thing. So it's one calf or one quad or one tricep, depending on the exercise. So for those whole body changes in electrolytes to cause very localized camping just actually seems like a bit of a strangely put logic. And there are days just that that probably gets you unconnected.
Christopher: Right. And I think I remember reading that and the book. They gave example of people that are performing intricate work with their fingers. They get cramp in their fingers but they don't get cramped in their quads, which makes a lot of sense. So, yes. All right. I guess we don't really have any good answers or causes. It seems like it might be more related to fatigue and something particular about the effort involved in making your race pace, length of time exercising and then maybe bike fit as well might come into it or running style or your gate, whatever it is for your sport.
Tommy: So what happens in muscles when they contract is you get some shifts in the electrolytes. So calcium is basically sheltered in that, which is then calcium is the thing which makes muscles contract. But potassium is also, as the more you contract, potassium is normally inside cells and also muscle cells and eventually from their basic contraction, then potassium sort of leaks out and it's not available there for normal contraction.
I think, again, it's also going to be partly on what you've done with that muscle, how used that muscle is to doing that work. And it might be to do with very local changes in the minerals or electrolytes but certainly not something that happens on a -- It doesn't mean that you need to be [0:48:00] [Indiscernible] to replace your potassium, which is what people -- That's a very standard advice, isn't it?
Christopher: Right. Exactly, yeah. And that sodium potassium requires energy, right? So if the cells run out of energy, could it be possible that the balance would be maintained for that reason?
Tommy: Yeah. No, absolutely. Yeah, if you're not getting -- If you're not getting the -- If your muscle glycogen runs out, you could definitely, you're calf bunks by itself and runs that muscle glycogen. Absolutely that -- Yeah.
Christopher: Excellent. Well, this has been a very fascinating and enlightening conversation, Tommy. Thank you so much for coming on and sharing all this. I know you did a ton of research to record this interview so I'm really, really grateful for your time. Is there anything we missed? I'm probably going to kill myself the moment I hang up thinking of something I missed.
Tommy: So I did have some theories about why people who are fat-adapted--
Christopher: Oh, we totally forgot about that.
Tommy: -- are less thirsty particularly during exercise, right? So one thing that we talked about initially or my first thought was that when you metabolize fat, you release water. It's called water metabolism.
Christopher: And this is why I'm not thirsty.
Tommy: Well, it might be part of it. So when, for ever gram of fat you use, you release 1.2 grams of water roughly. And so in traditional athletes who are running on carbs and gels and all that kind of stuff, they burn about half a gram of fat per minute on average. So that would give them 30 mls of water something an hour, which isn't very much. But if you look at the Volian, sorry, Phinneycan, Volek and Phinney, a very recent study -- I don't think they're published yet.
[0:50:06]
But we've seen some of the data. They've done online talks and stuff. And they've seen, in fat-adapted endurance athletes, they get up to two grams of fat, almost two grams of fat per minute metabolized which would then give you something like 120 mils of water per hour, which isn't that much but it is some. And then you also get -- So again, some of the studies that they did, Phinney did, 30 years ago now, they looked at keto-adapted cyclists and they still have about 25% of normal glycogen burning.
When you keto-adapt, you only lose about 25% of your glycogen and then it stays in the steady state about 75%. And you still use it. But again, at 80% lower rate. But when you burn glycogen, you release water because glycogen is stored with four times its weight, three to four times its weight in water. So even somebody who's keto-adapted, I did some calculations, you'll probably get 60 to 80 mils of water released from the glycogen that you burned even though you're mainly burning fat.
So that's like 200 mils an hour, which again isn't much but it might be enough for somebody who doesn't sweat much or you've got to a point where you're used to being dehydrated. And then your UCAN SuperStarch, for every gram of carbohydrate you burn, you release another half a gram of water. So, I mean, again, we're not talking huge volumes of water but that kind of stuff might be there to keep you ticking over.
And then an extra benefit I was thinking that you might get is that, again, your insulin levels are lower so you'll retain less sodium. And as you fat-adapt your base metabolic rate also drops. And so what, and I'm purely theorizing, is that you have an increased buffer for the amount that you can derange of physiology and still stay within the normal range. So, if your normal temperature is dropped a little bit because your metabolic rate is dropped because you're fat-adapted then your body temperature can increase more than somebody who's carb-adapted and still be within the normal range.
And again, same for sodium level. So your sodium, people who have lower insulin levels or fat-adapted, they tend to have lower sodium. Because their insulin levels are lower.
Christopher: Wait. So you're saying my metabolic rate is dropped because I'm fat-adapted or in ketosis. I mean, because I've seen maybe the opposite. My temperature is actually increased since I started eating a ketogenic diet.
Tommy: Yes. So again, that's very variable and that will just depend on how -- But for most people, when they reduce carbohydrates in their diet, their thyroid almost drop which reduces the stimulation of something called uncoupling proteins in the mitochondria which drive parts of our heat production. But again, some people talk about if you do a lot of things like called thermogenesis then you can up regulate your basic metabolic rate.
So it could be that your metabolic rate has gone up but for most people, it seems that metabolic rate decreases a little bit when they fat-adapt. And that's not a bad thing. That's just a normal response. But I was thinking that potentially, if your insulin levels are lower, then you have a greater, you have a bit of a buffer in terms of your sodium levels before you start to feel thirsty because they start slightly lower. And I have no idea if that's true. That was just a thought that I had. I'm trying to figure out why you are less thirsty when you--
Christopher: Yeah, it's interesting. I think all of this, the one thing that I'm starting to learn is that whenever you look at the recent studies, and it doesn't matter whether it's something that looks at exercise performance or whether it's a study that nutrition sciences, it hints at something that might be a solution. And sometimes the quality of the science is really shoddy and it's not a very good hint. And then sometimes it's much, much better.
For nutrition side, I just read an article in Slate Magazine when the reporter was talking about this and they'd obviously talked to Peter Attia again and talked about his thoughts on trying to improve the quality of the nutrition science. But even then, when it's really, really good, you still won't know how it applies to you and really the only thing you can do is your own experiment and take notice. So, okay, we've got this idea that when you get dehydrated you're going to be slower on your bike. Well, try and keep an open mind about either possibility because we know that the placebo is going to come into play or your beliefs are going to come into play here.
[0:55:00]
And then just do your own experiment. And if you find that you definitely are slower when you're even slightly dehydrated, then my advice would be to drink more. But just keep an open mind and know that just because you read something on the front page of the Osmo website it doesn't necessarily make it true.
Tommy: No, absolutely. Yeah.
Christopher: Yeah, thank you so much for your time. I really, really appreciate it. I know that you write and you have your own podcast. So, Tommy, how can people find out more of this good stuff that you offer to people?
Tommy: Yes. My website is drragnar.com. Ragnar is my middle name, if anybody is trying to figure out why on earth I've got that. But most of my stuff on there is general health. But I also deconstruct studies and trying to figure out and give a framework for people to figure out the best way to eat themselves healthier. And it's not just about food. It's about so much other stuff. So that's all on there. And I run the Eat Better Podcast, which you've been a guest on, Chris, and which everybody loves. So thanks a lot.
It's called Eat Better. And I run it with a girl called Chloe. She is from a website called Paleo Britain. And we do that together. So all of that can be found on my website. And you can download the podcast in hundreds of different ways, if you're into that kind of stuff.
Christopher: There's so many different ways. It's impossible to keep up with them all. Obviously, I'll link this. And I would highly recommend it especially for the people that you board with the Paleo chat. I'm not sure if it's the most recent episode now but the one I listened to on fish oil was fantastic. It's like you're going through so much detail and you've obviously put so much work into the preparation. I really learned a lot from that episode. I can't say that's true of every single podcast that I listen to now. Sometimes I realize it's entertaining but it's not really educational. So you're definitely on the educational side of that spectrum, which I really, really appreciate. Keep that up. I will link to it. Thanks very much.
Tommy: No problem.
Christopher: Okay. Cheers then, Tommy.
Tommy: Cheers.
Christopher: Bye.
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