Carbohydrates: The Good, The Bad, and The Ugly—with Dr. Asker Jeukendrup

We know we need carbs for training and racing, but what impact do they have on our health? We discuss the pros and cons with one of the world's leading sports nutrition experts.

Carbs: The Good, The Bad, The Ugly—with Asker Jeukendrup

Sports drinks, gels, and race food are focused on one thing—getting simple sugars from our mouths to our muscles. Research unequivocally supports their use for maximizing performance, but there’s also a mounting body of evidence that associates simple sugars with diabetes, heart disease, dementia, cancer, and other conditions. Because we care about both our performance and our health, we have to ask an important question: Where’s the balance?  

That is the central question of this week’s episode. Co-host Trevor Connor strongly believes that half of our current health issues would be solved by removing sugar-sweetened beverages, such as soft drinks, fruit juices, and many sports drinks, from our diets. But as always on Fast Talk, we want a balanced conversation backed by science. Joining us on this show to provide exactly that is Dr Asker Jeukendrup, one of the world’s top experts when it comes to carbohydrates and sports performance.

We start the episode by explaining carbohydrates, discussing misconceptions, and talking about why they’re needed for performance, even on low-intensity rides. We’ll also address many of the health impacts that have been tied to simple sugars, and share how exercise can mitigate those effects.  

Joining Dr. Jeukendrup are a host of leading experts, including coach and researcher Dr. Andy Kirkland, researcher Dr. Iñigo Mujika, coaches Joe Friel and Michael Crawley, as well as physiologists and World Tour coaches Dr. Inigo San Milan and Neal Henderson.  

If you’ve been wondering how to balance your performance with your health this is an episode you don’t want to miss.   

So, listen to this episode before you load up on your carbs—and let’s make you fast! 

RELATED: Fast Talk Episodes Training the Gut and Are There Benefits to Carbohydrate Manipulation? with Dr. Asker Jeukendrup.


Episode Transcript

Rob Pickels  00:04

Hello, and welcome to Fast Talk, your source for the science of endurance performance. I’m your host, Rob Pickels here with Coach Connor. Sports drinks, gels and race food are focused on one thing, getting simple sugars from our mouths to our muscles. Research unequivocally supports their use for maximizing performance. But there’s also a mounting body of evidence that associates simple sugars with diabetes, heart disease, dementia, cancer and other conditions. Because we care about both our performance and our health, we have to ask an important question.  Where’s the balance? This is the central question of today’s episode. Coach Connor strongly believes that half of our current health issues would be solved by taking sugar sweetened beverages, including soft drinks, fruit juices, and many sports drinks out of our diets. But as we always do on Fast Talk, we want a balanced conversation backed by science. We’re lucky to be joined by one of the top experts in the world on carbohydrates and sports performance, Dr. Asker Jeukendrup. We’ll start today’s episode by explaining carbohydrates, discussing misconceptions, and talking about why they’re needed for performance, even on low intensity rides. We’ll also address many of the health impacts that have been tied to simple sugars and share how exercise can mitigate those effects.  Joining Dr. Jeukendrup are a host of leading experts including coach and researcher Dr. Andy Kirkland, researcher, Dr. Iñigo Mujika. Coaches Joe Friel, and Michael Crawley, as well as physiologists and World Tour coaches, Dr. Iñigo San Millán, and Neil Henderson. If you’ve been wondering about how to balance your performance with your health, this is an episode you don’t want to miss. So listen to this episode before you load up on your carbs, and let’s make you fast.


Trevor Connor  01:56

Dr. Jeukendrup welcome back to the show. I was actually surprised when you mentioned it’s actually been a bit since we had you on the show. And I do apologize about that.


Asker Jeukendrup  02:05

It’s been a little while, but thank you for having me back.


Rob Pickels  02:08

I will say it has been a while. And I know that because in preparation for this episode, I listened to the previous two episodes that you recorded together. And there was no intro and outro music as you were reading the intro and the outro. And it really threw me for a loop. I couldn’t figure out what was wrong with the episode. And then I realized. So we’ve come a long way in our reporting and our professionalism and so we’re gonna do another even better episode, hopefully this time.


Trevor Connor  02:36

And we will not talk about the horrible intro music we did back then.


Rob Pickels  02:39

No. And you know what, maybe we won’t talk about Swedish Fish, which came up a lot in the past few episodes.


Trevor Connor  02:51

You know, I’ve actually had listeners of the show send me Swedish Fish. Apparently the thing that it’s associated with.


Rob Pickels  02:59

What’s the glucose fructose ratio in a Swedish Fish? Trevor, do we know what your intestinal absorption rate is?


Trevor Connor  03:06

Canadian or American? Because I’ve actually looked this up. Canadian version of Swedish Fish primary ingredient is glucose and then sucrose, so it actually has just the right mix of glucose to fructose. In the US, not so much.


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Rob Pickels  04:09

Well Trevor, we have Dr. Jeukendrup back on the show. What are we talking about this time?


Trevor Connor  04:13

So this is a big one. And this is going to be really hard to get into an hour, but the working title this episode that I’ve had is “Carbohydrates, the Double Edged-Sword” because and we’ll cover all this in the episode, it has been demonstrated pretty conclusively that if you want to perform at your best as an endurance athlete, you need carbohydrates.


Rob Pickels  04:34

And a lot of them.


Trevor Connor  04:35

And a lot of them. But now I’m going to put on my health hat, my dietary hat. It’s also there’s a ton of research showing that simple sugars, and we’ll get in minute into what are simple sugars, and free sugars, and added sugars and all that, that they cause a lot of the issues that we see with current chronic diseases. So what we want to get into today is the two sides of this sword and then where’s the balance? How to both optimize performance, but also make sure that you’re taking care of your health. So with that, why don’t we start and Dr. Jeukendrup, I don’t know if you want to give this definition or if you want us to throw it out there. But I’ve noticed a lot of people actually don’t fully understand what carbohydrates are. So do we want to give the two minute explanation of what are simple carbohydrates? What are complex carbohydrates? What are free carbohydrates?

Defining Carbohydrates

Asker Jeukendrup  05:29

Yeah, there’s quite a bit of confusion as well about what they are. And this is also why sometimes this topic gets quite interesting because people are confused about what carbohydrates and what complex and simple carbohydrates actually are. But if we start with the chemical formula, then the name carbohydrate already says that it’s based on carbo, carbon, and hydrate, hydrogen, and it also has oxygen. And a carbohydrate has a ratio of 1 : 2: 1 of carbon, hydrogen, and oxygen. And so all carbohydrates have that. So the most common one there is glucose, that is C6 H12 O6. As a small molecule, it is formed in a process of photosynthesis so it’s mostly derived from plants. But we do have glucose or carbohydrates in all living cells. So we know that glucose is a good fuel for the cell. For the muscle in particular. In the body, we store glucose as glycogen and glycogen is a starch. Now a starch is essentially a long chain of glucose molecules. And it is branch and therefore, like a compact way to store glucose. But glucose that like small molecule, we call it the monosaccharide and if we link two glucose molecules together, we get something that we call maltose or malt sugar. Another monosaccharide also is a very small molecule. So they’re almost a mirror image of glucose is fructose, we’ll probably talk about that quite a bit as well. If we combine glucose and fructose, we get something that we call sucrose. And that’s actually the most common sugar, it’s table sugar. And there’s one other monosaccharide in our diet, that is galactose. It’s not that prevalent in the diet. But if we combine it with glucose, we get lactose. And lactose is very common in milk, of course, is milk sugar. So these mono and disaccharides, they’re all sugars. And they have varying levels of sweetness with fructose being the sweetest. So that’s a little bit about sort of the sugars. And then you have the complex carbohydrates. They are the larger chains of glucose molecules. And if we have chains that are somewhere between six and 20, glucose molecules, we call them maltodextrins. That’s something that we find in a lot of sports nutrition products. And if we have very large chains, hundreds, then we call them starches. And there are different types of starches as well, depending on how many branches you have in that molecule. So that’s essentially what what carbohydrates are. And then some of the misunderstanding comes from the idea that simple sugars are fast and complex, and carbohydrates are slow. And that is one of the things that’s not true because you can have simple sugars that are fast, but simple sugars like fructose and galactose actually very slow. And when we talk fast or slow, it actually means like how rapidly does it change blood glucose concentration or how rapidly does that carbohydrate enter the circulation. The other misconception is that complex carbohydrates are generally believed to be slow, but they’re not, at least not all of them. Some of them behave just exactly like glucose.


Trevor Connor  09:03

But I think a really important thing for our listeners to understand is ultimately, and you brought up the three monosaccharides and I would just say to keep the rest of this conversation simple, we’ll just throw out galactose for now. We’ll save that for another conversation and really just talk about glucose and fructose. But whenever you’re talking about carbohydrates, whether it’s a chain of hundreds of glucose molecules together, or just a chain of glucose or fructose, are just the straight sugars, which you actually rarely consume is just a straight sugar. Ultimately, in our body, they all break down to glucose or fructose, and that’s how our body uses them. I think that’s really important to understand. I’d say the third misconception that’s one I have to address all the time because I don’t eat bread or pasta is I always get asked,


Rob Pickels  09:51

You don’t eat what Trevor?


Trevor Connor  09:52

Bread or pasta.


Rob Pickels  09:53

Pasta, is that pasta that you ate yesterday?


Trevor Connor  09:56

Oh, what do you do? The American version?


Rob Pickels  09:59

The pasta.

Sources of Carbohydrates

Trevor Connor  10:01

I always get asked the question when I tell people I don’t eat bread and pastas, how do you get your carbohydrates? And it’s important to understand there are other sources of carbohydrates. So people constantly called bread carbohydrates. Yeah, that’s not really accurate. Breads contain a lot of carbohydrates, but there’s a lot of foods that contain carbohydrates. And just like bread, fruits and vegetables, their main macronutrient is carbohydrates. And a lot of people don’t understand that. As a matter of fact, I personally don’t like referring to foods like pasta and bread as carbohydrates or meats as proteins, I think that’s an oversimplification. It was actually this great review meta-analysis that just came out a couple months ago called “Dietary patterns and non-communicable disease biomarkers.” It’s basically looking at the effects of popular diets on markers of disease like cancer and heart disease. And one of the big conclusions in this meta-analysis was that diets that focused on macronutrients, so high fat diet or low fat diet, high carbohydrate or low carbohydrate diet really had no correlation whatsoever with improvements or worsening of these biomarkers. The three diets that scored the best in terms of reducing these markers of disease are all diets that focus on what foods you should and shouldn’t eat. And that was the, in order, the Paleo diet, the DASH diet, and the Mediterranean diet.


Rob Pickels  11:28

I had somebody that was deep into bodybuilding telling me that they didn’t eat carbs as they were eating a bowl of vegetables. And it’s like, well you might not eat high carbohydrate diet, like a bread based diet, but you’re definitely eating carbohydrate right now, as we talk.


Trevor Connor  11:42

It’s important to remember as we define carbohydrates that sometimes we get too focused on the macronutrient and not enough in the foods themselves. That’s the point that Andy Kirkland made for us.


Andy Kirkland  11:53

I suppose I’m driven just as much by my personal beliefs as the evidence, in so far as that, I think there’s too much of a focus on the actual macronutrients, rather than the quality of the macronutrients. For example, bread is of very good source of carbohydrate. So how can we bread in its most simplest form with fewer flour improvers or levels of yeast? And the answer is, eat good quality bread with two or three ingredients in it and not processed. My experience, as well as being over in Kenya was that my diet was really simple. I’m a vegetarian, so it was quite challenging at times, but I had really nice chapatis, lots of green vegetables cooked in coconut and stuffs. So really, really nice to eat in a sufficient diet with really high quality macronutrients. So there’s more than one way to skin a cat. And I would suggest focusing on the quality rather than the actual macronutrient. And not worrying too much about the exact composition of that diet. As long as it’s high quality foods and nutritious food.


Trevor Connor  13:15

Dr. Jeukendrup, the other thing that I think we need to define for people is what’s meant by free or added sugars.


Asker Jeukendrup  13:21

Yeah, so added sugars are usually sugars that are added in the process of cooking or preparation of food. And free sugars is something similar. They are the sugars that are added to our food, or the sugars that we find in fruit juices essentially, or in milk. So the definitions that are used in many studies, because it’s difficult to distinguish like the sugars that are sort of naturally part of our our diet, and then the sugars that are added to products. So that’s why the distinction is often made. In the body, they will actually have exactly the same effect, of course, so whether sugar is added or it is part of your fruit or something, your body really will not know the difference. But of course, a lot of the carbohydrates that we eat or a lot of the sugars that we eat are added sugars, and they are luxuries that we could actually avoid or easier.


Trevor Connor  14:23

So something and I want to jump here quickly because this is something that you’ve done a lot of research on. I would say it’s been proved pretty conclusively that if you’re an endurance athlete, and you’re looking to perform so this isn’t, “Hey, I just go out and ride an hour every day really slow and easy.” This is “I am in a race and I need to be in the sprints. I need to be in the attacks towards the end of the race.” I would say it’s pretty resolved science that you need carbohydrates for that. And like I said, you’ve done a ton of research on that so maybe you can give us the couple of minutes summary on why they are essential.

Why are Carbohydrates Essential?

Asker Jeukendrup  15:03

Yeah, I think there’s overwhelming evidence that during prolonged exercise that carbohydrate can help. And help means that it reduces the onset of fatigue, it reduces the perception of the effort added improves actual performance when you measure it. We can see that from exercise that is roughly like already one hour, like in the past, people told oh it needs to be two or three hours before carbohydrate have the effect. But we can already see the effects during just one hour of exercise and probably for that type of exercise, the amount of carbohydrate you need to get the improvement are actually really small. Then if we move to two or three hours, it is a slightly different mechanism. Two to three hours of exercise or longer than carbohydrates actually provides the fuel for that exercise. And studies have shown that if you don’t feed carbohydrate, and just drink water for example, that like a few things happen; your blood glucose concentrations will drop over time, and it will go lower and lower and at some point, you will start to feel dizzy and weak and we call that hyperglycemia, or bonking, or hitting the wall depending on what what you’re doing. At the same time as your blood glucose is dropping, you also are using less carbohydrate as a fuel, and any more intense exercise will require some level of carbohydrate. And if your carbohydrate oxidation drops below a certain level, that means you cannot sustain that exercise intensity anymore, and you need to slow down. And the way to prevent that is by making sure that you have a constant supply of carbohydrate by feeding. And the recommendation generally are somewhere between 30 grams of carbohydrate up to like all the way 90. And more recently, studies have published where they gave 120 grams of carbohydrate per hour, so a very large amount.


Rob Pickels  17:11

I think something that’s worthwhile to also point out is that ensuring that your glycogen stores or that your carbohydrate stores remain elevated during exercise also decreases a cortisol release during exercise, protein oxidation muscle breakdown. So there is a lot of other ramifications beyond just the performance that we’re talking about in terms of recovery, or the risk of LEA, low energy availability, and RED-S, all of that. So definitely a complex conversation and individuals, if you want to dive into it more deeply, we did do two past episodes. Eighty-three was with Dr. Jeukendrup on training the gut and Fast Talk 150 was on the benefits of carbohydrate manipulation. Can you by increasing or decreasing carbohydrate, can you elicit different adaptation within the body. So definitely go back and listen to those.


Trevor Connor  18:01

And another thing that’s really important to raise here is you’ll have people say, “Well, I’m not going hard. I’m going long today, but I’m going slow. So I don’t eat carbohydrates because you get that energy from fat.” I don’t think we need to dive into the physiology here, but there’s an expression in exercise physiology or general physiology that fat burns on a carbohydrate flame. Your body actually can’t use fat for fuel unless glycolysis is operating is the real short explanation of this. And glycolysis is powered by carbohydrates. So even if you’re going slow and mostly relying on fats, you’re still burning carbohydrates. And you might not be burning them rapidly, but if you’re going out for a four or five hour ride, your body doesn’t store many carbohydrates, you’re gonna go through them pretty darn quickly.


Rob Pickels  18:49

Well, to put that into perspective, I’m certainly a carbohydrate based athlete based on just my power profile and my metabolic system. And even Trevor, if I’m riding at a millimole of lactate, well within my base zone, I’m going through at least 600 kcals an hour from carbohydrate based on multiple testings that we’ve done on myself over the years. So, you know, in a two hour ride that’s 1200 kcals there, nevermind a four or five or longer hour ride. Even though I’m going easy, I’m crushing those carbs.


Trevor Connor  19:20

Dr. Jeukendrup anything to add to that? Because that really is your area.


Asker Jeukendrup  19:24

Yeah, no I think it’s actually an important comment because I come across a lot of athletes who say, “I don’t want to take carbohydrates because I don’t need them and they contain so many calories.” But if you just in this example, if you’re using 600 calories of carbohydrate, there’s almost no way that you could actually eat that during the activity. So even if you have quite high intake rates of maybe 90 grams an hour, you’re not even approaching that. So it’s yeah, there’s no risk of gaining weight while you’re doing that sort of activity.


Rob Pickels  19:58

And I will say while we’re on this topic and I don’t want to steer us too far off this direction, but as we discuss the health implications of simple sugars within our diet, I will say, as I have learned how to add more carbohydrate into my cycling, it has reduced the need for me to eat carbohydrate and all of the other hours. Doing a better job of fueling while riding, trying to limit that glycogen depletion means that the rest of my diet doesn’t have to have as many carbohydrates and sugars in it. So even though I’m taking in a lot, I think ultimately we’re going to discuss, it’s better in the long run.


Trevor Connor  20:37

So before we jumped to the other side of this sword, I want to throw one other argument here for carbohydrates. I’ve heard from a lot of people who are on the keto diet goes, “Well, you know, I’m on a keto diet, I eat virtually no carbohydrates and I do okay.” So there’s your argument that glucose isn’t necessary. Well, glucose is the primary fuel of your brain. And yes, your brain can use ketone bodies for fuel. But something for even people on a ketogenic diet need to understand is if you aren’t getting carbohydrates, your liver is going to convert about 40% of those ketone bodies back to glucose so that your brain has fuel. Your brain will die without glucose. So there is definitely a need for these sugars in your body.


Asker Jeukendrup  21:24

Yep, no, I agree.


Rob Pickels  21:26

Good old gluconeogenesis.


Trevor Connor  21:28

So let’s jump to the other side of this, which is, obviously there’s there’s a ton of research showing that, and right now I’m just going to focus on those simple or added or free sugars. And a ton of the research actually looks at sugar sweetened beverages, so your soft drinks, fruit juices, and I hate to say this, sports drinks. And there’s a lot of research showing that there are negative consequences to eating a large quantity of simple sugars in your diet. And I actually struggle with this Dr. Jeukendrup because I knew this was the part that I was going to have to bring to the conversation so I started going through the research. And it was picking the studies that was actually kind of difficult. So I will say to our audience, we will have a very long list of references in the show notes for this.


Rob Pickels  22:17

Trevor and I were prepping for this episode and he was like, “Oh don’t worry, I put that study and read cube” and read cube is what Trevor and I use to organize our research. And I was like, “Oh great, I’m gonna go, I will go look up that research.” There was like 80,000 studies in our folder for this episode. I was like, “Trevor, man, I can’t find the one that you and I just talked about.”

Too Much Added Sugar Can Be Damaging to Your Health

Trevor Connor  22:38

Yeah, so let me try to take all this and just put it into five minutes. And then please, Dr. Jeukendrup, you can jump in and respond to all this. But what I’m trying to explain in these five minutes is there is pretty strong evidence that having too much simple sugar, too much added sugar in your diet can be really damaging to your health in a lot of ways. And I think people, I’m actually not going to talk much about diabetes because I think most people understand that, but there’s a lot of other conditions that it contributes to. And so, you know, there was a fantastic review in JAMA, very high impact journal, looking at the nhaynes 3 data, and basically showed that sugar consumption correlated with all cause mortality, found multiple reviews that show that correlated with heart conditions, basically all cause mortality. In terms of heart disease, multiple, multiple, multiple studies showing a positive correlation with cardiovascular disease with heart disease was stroke. And again, we’ll put all those references in there. Some of the more interesting research has really looked at the effects of sugar on the brain. And there was actually a couple studies that I wrote an article back in 2017, that showed that higher glucose diets can really contribute to the risk of dementia. And one of them that was quite concerning looked at the brain volume. Correlations between brain volume and again was looking at sugar sweetened drinks, so soft drinks, fruit juices, and showed that consuming these beverages the higher consumption of these beverages actually reduced the size of the brain that was basically equated to aging in the brain. It made the brain look much older than it was. And sorry, I’m given a very simple explanation of a very long study because I have a lot to go through here. But yeah, if you’re interested in the study, title of it is “Sugar and artificially-sweetened beverages and the risks of incident stroke and dementia.” And it’s quite an eye-opening study. I mentioned I wasn’t going to cover diabetes, but we had that conversation with Coach Joe Friel. Let’s hear what he has to say about the health impacts of simple sugars on diabetes.

Health Impacts of Simple Sugars on Diabetes

Joe Friel  24:50

It’s a double-edged sword. What one of the edges is now the leading disease is related to one of the leading diseases in this country, which is diabetes, type 2 diabetes. That’s the fastest growing disease in the country, in fact, in most civilized parts of the world, and a lot of that has to do with the fact that we’ve become extremely carbohydrate rich in our diets. And so I understand that, you know, it’s important to have carbohydrate to perform well, that’s important. But I’m afraid sometimes that the athlete who receives that message thinks that means, “I should eat much, much more carbohydrate.” And that person may not, should not be eating necessarily more carbohydrate. That person actually should be limiting their carbohydrates, or A1c, is off the scale and we’re telling them to eat more carbohydrate, that’s really not a sane thing to be doing. So that always concerns me. But you know, there’s the other side of the coin, which is the science as well, you have to have it to perform well. You know, so I always deal with that in my own head. Who am I telling this to? Who am I having this conversation with on Twitter and saying eat more carbohydrate. I’m not sure it’s a healthy thing for us to be talking about. I would suggest that what athletes should do is get a physical once a year and the physical should involve a blood sample, which looks at lots of things. But I would ask my physician to look at my A1c, HbA1c, and the physician will know exactly what that is. And the information you get back from that is very important. That’s going to determine what you do going forward as far as your diet. It’s not as simple as saying no carbohydrates, or eat lots of carbohydrates, because there’s lots of things we call carbohydrate. And having more, the more basic ones like fruit is much better for you than eating a piece of cake or a slice of white bread. You know, there’s all kinds of things we can do here to modify your intake of carbohydrate. But the starting point is to find out if you’re sensitive to carbohydrate. That’s where your physician comes in. That’s where getting an annual physical comes in very handy. And again, ask for HbA1c review from your blood sample.


Trevor Connor  27:09

Continuing on down, there’s certainly been correlations with cancer. One of the more controversial actually, and Dr. Jeukendrup you might want to jump in here, is the correlation of sugar consumption and the obesity epidemic right now. And there’s been people that have written research on both sides of that. There’s certainly high correlations with sugar consumption and obesity. But one of the counter arguments and we can discuss this if you’d like is, you don’t see sugar contributing to obesity without also a concurrent increase in calorie consumption. So that’s the argument against the counter argument to that is, obesity is always calories in calories out. You’re over consuming, so you can’t raise weight gain without actually consuming more calories. And the argument here is that sugar actually causes us to consume more calories, but Dr. Jeukendrup, I know you’ve had some opinions on this. Is that something you wanted to speak to at all?


Asker Jeukendrup  28:06

Yeah, I think this is a really important point. I think if you go through all those studies, the vast majority, I would say almost all of them are using sort of excessive sugar. And again, depends maybe a little bit on what you call excessive, but it’s usually in those studies. There are very few of those studies where subjects were an energy balance, or people weren’t adding energy balance, or there epidemiology studies where just over time, people are tracked, but they’re also gaining weight. If you’ve filtered on energy balance studies, you may get slightly different results. But I think the overall point I think here is really important is overwhelming evidence that if you consume too much sugar is going to have all sorts of negative effects. And whether that is a direct effect of the sugar, or it’s an effect of the increased energy balance, and then maybe increased weight, which then has all sorts of negative effects from a public health point of view is almost like it’s almost not important. It’s like you’re consuming too much sugar so you need to you need to reduce it. But that evidence is pretty strong.


Rob Pickels  29:20

I think that the research looking through this is at times difficult to I don’t want to say comprehend, right? That’s not the right word. But we have all sorts of different research that’s occurring here. And as Dr. Jeukendrup points out, if we have an isocaloric study where there’s controlled feeding, you know, exactly the number of calories that somebody is eating, and maybe they have their calories from a low glycemic index or from a high glycemic index or a high fat, low carbohydrate, then we certainly we don’t see things like increases in body weight, changes in body composition, so on and so forth. But I do have to ask, you know, is that reflective of people’s daily lives? Because we’re not necessarily controlling, a lot of people are not putting everything they eat, they’re not weighing, they’re not looking at every calorie in and every calorie out. And there is certainly research that says, hey, when you consume a diet that is higher in sugar or a simple carbohydrates added free, then your energy intake also tends to go up as well. And we can talk about maybe the insulin mechanism that causes that. But I will say on the other side of this research too, there is research that shows, hey, if you just inject glucose directly into this cell, all of these absolutely crazy things happen. And I also have to ask is that reflective of regular life as well, because we’re not necessarily doing that, right? And so a lot of these studies, they’re interesting, from a conceptual level on both ends of the spectrum. I’m decidedly in the middle of this conversation, this is one of those things where it’s kind of like, I don’t know, if I quite know, and I don’t know if I’m quite willing to like, you know, really stick a fork in it and say it’s done but.


Trevor Connor  31:09

Well, I’m going to kind of finish this conversation of the health impacts of sugar, with one study that actually just came out. So this came out in 2023 and we’re just in February of 2023. This was in BMC, which is high impact journal.


Rob Pickels  31:26

I definitely haven’t read it yet then.


Trevor Connor  31:27

And it’s called the “Associations between types and sources of dietary carbohydrates and cardiovascular disease risk.” And just like a lot of studies I was bringing up, it showed that, so important word here, free sugars, were positively associated and highly associated with cardiovascular disease, heart disease, and stroke. And even showed that just a five percent replacement of free sugars with non free sugars actually substantially reduced the risk of these diseases. But what I found particularly interesting about the study, and I think this is where we’re going to end up going to in this conversation, was that the quality of the carbohydrate was more important than the quantity of carbohydrates for cardiovascular disease. So when they looked at total carbohydrate consumption, there was actually no correlation. When they took fruits and vegetables out of the conversation, which have no free sugars, by their definition of free sugars. And those are what they would consider your your healthier forms of carbohydrates, and just looked at, you know, sugar sweetened beverages, things like that. So these free or added sugars, then all of a sudden there was this high correlation. So the argument of this study is it’s the sources of the carbohydrates, less so than just eating carbohydrates themselves that are the the risk factor.


Rob Pickels  32:49

Yeah, certainly. And to add to that, just for clarity, the free sugars are sugars that are being added to foods and then also things like honey, syrups, and fruit juices all fall under the free. Whereas the sugar naturally found in a strawberry, or an apple is not a free, that’s part of the fruit, the vegetable, that’s okay. You squeeze that apple, you get the juice out of it, now we’re talking free sugars that seem like they have a negative impact. And I do I love to say this, people have to remember that things like sports drinks are basically just soda that’s not carbonated. A lot of people think that that’s healthy and as you pointed out earlier, it doesn’t count.

Quality of Carbohydrates

Trevor Connor  33:28

Let’s hear from Coach Neil Henderson, it talks a little more about the importance of the quality of carbohydrates.


Neal Henderson  33:33

A few real key things to think about is you know, the quality of the source of that fuel, you know, highly processed super simple sugar, versus a piece of fruit. Definitely a little bit of a different profile in terms of just the nutrient density, their activity and what you’re doing in your training. Again, a steady endurance training session, you don’t need to absolutely maximize your carbohydrate stores before, during and after. It’s kind of like, if you were doing all your training in your fastest wheels with your lightest tires, in your skin suit with your fastest helmet, you don’t have that like race day little bump that you get. So it’s okay to have some times where you’re, you know, a little bit less than ideal, I would say in terms of pure total energy intake relative to a given training session. And then you have the timing of things of when are you eating those kinds of carbohydrates and, you know, again, if you’re during exercise, there’s a difference. If you’re eating that kind of, you know, high carbohydrate fuel when you’re way far away from training and how high bolus is without adequate balancing fats and healthy fats and protein, then yeah, you’re definitely rolling the dice and the in a bad way for all of those things for potential development of diabetes, as well as just having that massive instability of your blood glucose. So too much of a good thing is always just that.


Trevor Connor  34:58

So Dr. Jeukendrup we’ll throw this to you now because this whole conversation has been about the average population. Certainly many of the studies included physically active people. But exercise can have beneficial effects or counter effects on everything that we were just talking about. And certainly something we didn’t even bring up is the fact that one of the ways simple sugars impacts our health is they spike insulin, but exercise can counter some of that. So did you want to talk about some of the ways that exercise can help mitigate these negative health effects of simple sugars?

Exercise Can Help Mitigate Negative Health Effects of Simple Sugars

Asker Jeukendrup  35:34

Yeah, and I think one other important point to make is that in the vast majority of studies, exercise is not part of the equation because it’s the general population. So there’s a lot of inactivity in the population, unfortunately. And so these studies do not take exercise into consideration or at least if you would end up with a very small number that have incorporated exercise. And exercise, yeah, is a major modifier of the effects of sugar and it makes you more insulin sensitive. So you need less insulin to remove glucose from the circulation. You will be better at maintaining a normal blood glucose concentration. So that is just one of the effects of exercise. So definitely a very important modifier.


Trevor Connor  36:24

Yeah, and for listeners who don’t know, if you consume what’s called a high glycemic index meals is something that really spikes your insulin and you keep doing that your body can desensitize to insulin, and that leads to potentially diabetes if you do that too much. But when you are exercising, that insulin response is actually shut down. And muscle cells that are doing work, can take up that glucose without needing insulin to get them to take it up, which is really fascinating thing about the human body.


Asker Jeukendrup  36:57

Yeah, and the effect of insulin or the effect of exercise on so insulin sensitivity is also an effect that that is acute, but it’s also a longer effective and can last up to 48 hours. There’s even discussion whether there’s actual training effective lasts even longer than that. But like because a lot of athletes will train at least once every 48 hours, that you you almost have a constant improvement in your insulin sensitivity as a result of that.


Trevor Connor  37:26

Yeah, so something else to bring up about insulin and you’re talking about the longer term effects of exercise, I actually read a really interesting study that showed that exercise increases levels of brain derived neurotrophic factors and can keep those elevated for a very long time. And those actually also influence insulin sensitivity. So there’s one of the mechanisms by which exercise keeps us more sensitive to insulin. But Dr. Jeukendrup throwing it back to you, what are other benefits of exercise when it comes to the simple sugars and these health effects?


Asker Jeukendrup  37:58

Yeah, so I think that if I sort of you make the question really simple is why would this be any different for our athletes, right? Because athletes are active, they do exercise, they ingest very large amounts of glucose on some occasions. So why would it not be unhealthy? And I think one point we already touched on is that as an athlete, you use this carbohydrate as a fuel. Like in the oxidation studies that we did, we showed typically that 70 to 80% is immediately oxidized during that activity. So you wouldn’t have to worry about that 70 of 80% that you’ve ingested anyway. And the remaining maybe 20%, that is not immediately oxidized, will probably be stored as muscle glycogen so you can use it later. So also, not really a concern. There’s not a lot of available sugar that could cause any harm. I think the stable isotope studies have also shown that, so they show that 70 to 80% is used. But we’ve also shown that very little or nothing of that label actually ends up into triglycerides, for example. We can talk about that more when we talk about the fructose, specifically because the overlap of genesis is usually linked to fructose ingestion. I think we talked about how exercise so that it helps you to normalize your blood glucose improves insulin sensitivity. And I think athletes in general are also like weight stable and we have very few studies where the subjects are weight stable and any negative effects of sugar have been observed. There are some and actually we’ve done a study that we can also talk about where we gave carbohydrate, like high carbohydrate diets to athletes. This was a situation of relative overfeeding of carbohydrate, so we fit them in energy balance. It was a study that was done in metabolic chambers. So the subjects actually were followed for 10 days, we gave them all of the diet. So everything they ate was provided by us. They spent three of 10 days in a metabolic chamber, we measured the remaining days, we measured the energy balance using doubly labeled water. So it was a very involved study, very, very controlled study. And we gave them a lot of carbohydrate, very high carbohydrate diet, we exercised them two hours per day. So during that exercise, they were using a lot of fat, and then the diet contains so little fat, mostly carbohydrate, that it wasn’t actually replenishing those fats. And that was our main question in that study. If you are using this fat every day, but you’re not replenishing it, what happens? Will you lose fat? Or will your body turn carbohydrate into fat? We measured body composition before and after, and that didn’t change. So that already suggested that you started turn this carbohydrate into fat. And when we use stabiliser dog tracers, we could actually find that the tracer ended up in some of the triglycerides. We saw increased triglyceride levels. So that is a situation really extreme 5000 calories per day, they were expending almost 5000. And in that situation where they were in energy balance, you still see that because you’re over feeding them on carbohydrate. They were in positive carbohydrate balance that some of that actually ends up into in triglycerides. So you do get some de novo lipogenesis, you can do get some increased plasma triglycerides. So they’re not probably not from a health point of view, things that we probably wouldn’t want.


Trevor Connor  42:03

It is interesting that the liver’s ability to convert carbohydrates to fat is actually somewhat limited. So it sounds like that obviously got ramped up pretty hard. But my guess is also their bodies were becoming increasingly reliant on carbohydrates for fuel. So that’s your oxidative priority. And we’re probably just been very sparing and using fat. Did you see any of that?


Asker Jeukendrup  42:27

Not so much in this study. I mean, you do see like, an adaptation to, yeah you use more carbohydrate, but you still also in that situation also use a lot of fat still. But I think it’s quite an extreme study because we have two conditions. All the subjects that this twice and one had only 20% fat, and then one condition only 2% fat, so really, really extreme. And that will also be sort of one of the messages are there, there’s really no need, or the probably, the advice wouldn’t be to go down to that extreme, really no need.


Trevor Connor  43:05

It’s really important to remember that elite athletes and amateur athletes are different and may handle simple sugars differently. As Dr. San Millan explains, in this clip, top cyclists have a remarkable ability to handle sugars. But that doesn’t mean we all do.

Quality of Food

Dr. Inigo San Millan  43:19

We try to have the best quality of food available to start with by we’ve done spare money and that and we have a great nutritionist and a team who does a fantastic job called cabrito. It takes care of all the DIS details about the nutrition of the athlete, the Yeah, for sure. One thing is like you need to put like simple sugars in that engine, right, especially during the competition. Whereas outside of competition, we might want to focus on more complex carbohydrates with a lower glycemic index and a very good quality of food, in spite of like our white flour, the main weight and higher in fiber content. But yeah, in the competition every day, you need to really get gas, fast to the muscles, right and simple. Carbohydrates are the way to go at this point. And that being said, we’re working with a very special population. These athletes in the Tour de France, they consume about 2000 calories a day of simple sugars. So imagine a human giving them that entire caloric expenditure for most people out there, right? So non athletes, right? So imagine giving someone a bowl of sugar, worth 2000 calories a day and this hate is your entire food for the entire day. Just eat the sugar, right? Most people will end up either has been hospitalized or dying or becoming diabetic, right? We know that elite athletes they can handle that because their superior metabolism and mitochondrial function, which is just you can throw racing to those mitochondria, and they will convert into energy somehow. So we know that at some point doesn’t have those effects. Next, because we don’t see prevalence at all of type two diabetes, pre type two diabetes, obesity in the acquired forums, it there’s something like that, which is really rare, maybe genetic. But yeah, we don’t see that or cardiovascular disease, you know, any farther more when they finish their career, if they continue to be inactive, and they don’t need to have so many gels and sports drinks are so anymore, right? They just continue active; they tend to be a still a very healthy population. They don’t seem to pay off all these years having so many simple sugars, we don’t see that, as opposed to like, if you stop completely alone from training and competing, yeah, people gain a lot of weight and they become a normal person already. And that’s when he could have been carbohydrate for so it’s going to be not good for you. Yeah, but the same thing happens also, this is where my colleague, Rick Johnson, at the University of Colorado, he’s a world authority in chronic kidney disease and fructose. And this is an area that he’s been working for, for a while into the effects of fructose and the body. And this is where we’re trying to put together some grants or some studies, because fructose has a very similar pathway as glucose, and it comes to pyruvate and be oxidized in mitochondria under resting or postprandial conditions. And so if you don’t have a good mitochondrial function, if you’re diabetic or pre diabetic, or you have cardiovascular or cardio metabolic disease, historically, you know, doctors are telling, Hey, eat a lot of fruits and vegetables, but fruits are very, very good, but at the end of the day, fruits are simple sugars. So we need to also be careful out there without having a lot of fruits because of the fructose and implicating some metabolic disease and health.


Trevor Connor  46:49

listeners. Are you struggling to finish your workouts or your races? It’s Steve Neil performance, you’ll discover the proper nutritional balance that you need to finish workouts and races strong both in body and in mind. The coaching and testing services that Steve Neil performance offers are uniquely crafted specifically for you, no matter your athletic level, stop waiting to fix your energy deficit issues yourself. check out Steve Neil today. Now, that’s interesting, because that reminds me a little bit of a study that was actually just done last year. So this is a study called a high carbohydrate diet with a low glycemic index improves training effects and male endurance athletes. I don’t know if you’ve read this one. But this is a study where they had three protocols. They had subjects that ate a high fat, low carb diet, they had subjects that ate a high carbohydrate diet that was a high glycemic index. So a lot more simple sugars that were really raising insulin levels. And then they had a group that also ate high carbohydrate, but they were eating much lower glycemic index. So more whole grains, more fruits, more vegetables, keeping the glycemic load down. And what they found in this study that was very interesting was, you know, sure enough, what you’ve already demonstrated, the people on the high fat diet saw a big drop in their peak power. So they could go at low intensities really well, but they lost that ability to go high intensity. But what I found fascinating about this study was the group that was high carbohydrate, high glycemic index, lost some metabolic flexibility, meaning they became overly reliant on carbohydrates for fuel and their ability to burn fat for fuel was reduced. The group that ate high carbohydrate but low glycemic index, maintain the highest flexibility, meaning they saw improvements in their ability to use fat for fuel at at lower intensities. But they also had that ability to use carbohydrates at high intensity and keep that ability to put out big power.


Rob Pickels  48:54

Yeah, what’s interesting about this study was the high fat diet saw of the three groups the largest improvement in their power threshold, and the high glycemic the lower Thresh. Exactly, yes. And the high glycemic index saw a small but the smallest improvement in threshold, so kind of flipped there. And for clarification, if anybody’s interested in these glycemic index numbers, the high group I believe was over a glycemic index over 70 and the low glycemic carbohydrate group was glycemic under 50. Yes, good memory. I tried to read as many of the 80,000 studies you put in the read cube folder as I could, and I definitely read this one so


Trevor Connor  49:39

I did not have a very active weekend. That’s all I was thrown study after study out of Rob going you gotta read this. You got to read that it was actually fun research. So shifting gears. Obviously, in the research, they constantly talk about sugar sweetened beverages and sugar sweetened beverages use high fructose corn syrup. So there has been in a lot of conversation about the damaging impacts of fructose, and it is important, I don’t think we need to dive too deep into the physiology, that fructose and glucose are processed differently in the body. For one thing, glucose can go directly into your muscle cells and all your cells and be used for fuel. We’re fructose is almost exclusively processed in the liver. So doctor, you can drip did you want to kind of address that and some of the health impacts that people bring up about fructose?


Asker Jeukendrup  50:28

Yeah, I think as a result of that, because of this process in the in the liver, and it needs to be converted into glucose before it or lactate before it can be used as a as a fuel. It is it’s therefore more likely that it’s converted into something else and it’s converted into fat. And there is quite a bit of evidence mostly from animal studies, but also a human studies that fructose overconsumption has an effect on insulin resistance impairs glucose tolerance, hyperinsulinemia hypertriglyceridemia hypertension. So that’s it’s pretty convincing. But all of those studies are really with overfeeding. And again, if you then filter and go to studies where there’s no overfeeding and fructose actually given in more physiological doses, then it’s actually really difficult to find the effects on even overlap market Genesis, for example, and I think it’s studies by looked up II in at the University of Lausanne is his ation is really nicely that in sort of energy balance, and then labeling the carbohydrate or the sugars and really couldn’t find much of that label back into triglycerides. So the overlap of Genesis in those studies was really minimal. And the only evidence that I know is that this can actually happen at higher rates in energy balances the study that that we did, but it is extreme in another way. And that in that we really fed them extremely high carbohydrate diets, we made sure that they were using a lot of fat every every day by exercising them quite a bit. So in that extreme case, you do see some light proGenesis. But in some of the other studies by looked at p and others, you don’t see that.


Trevor Connor  52:22

Now, the only thing I would bring up in this is less than the athlete population more in a sedentary population. But actually look at some of your research. You’ve pointed out when we maximize our absorption of simple sugars, your body can absorb glucose and fructose at about a four to one ratio, meaning we can absorb a lot more glucose per hour than then we can absorb fructose, which indicates that our bodies evolved around much more exposure to glucose and fructose. And the one issue I’ll point out is when you’re talking about high fructose corn syrup, so one of the more popular forms is 55%. Fructose, to 45% glucose, which is completely the wrong ratio to what our bodies used to handling. And the one concern I have, particularly when you’re dealing with children who often eat a highly processed diet with a lot of high fructose corn syrup is they might actually be able to handle a lot of glucose they’re getting but they’re getting more fructose and their body is is designed to really handle and that’s why I think in some sedentary children, you’re you’re seeing some of this non fatty liver disease because they’re getting so much fructose in their liver and the liver has nothing that can do with it, it’s getting converted to fat and deposited in the liver. Would you agree with that?


Asker Jeukendrup  53:37

Yeah, although I would make the point that probably the biggest risk there is not so much that it is that particular sugar, the risk is that they consume so much of that sugar, which makes it makes the food taste nicer, so they eat too much. And that really is the key of the problem. Plus, I think we touched on this a little bit earlier that some of these sugars, they are just generally very low-quality foods. So if you would replace those sort of low quality foods with higher quality foods, complex carbohydrates, and sort of more whole foods that would come with a lot of other sort of health benefits that you’re not getting if you just have these sort of sugary drinks that don’t really give you much other than good taste maybe and so managing too much energy properly.

Glycemic Index of Fructose

Rob Pickels  54:31

And so I’d love to throw something out there and this is a correct me if I’m wrong type of situation because it explains my understanding. And that is as we mentioned before, glycemic index has to do with how quickly your quote unquote blood sugar raises. And at that point, we’re worried about glucose. As you consume glucose it goes directly from the lumen of your gut into your bloodstream. That’s why glucose is a quote unquote quick sugar because it goes straight in the bloodstream. We measure that increase very quickly. Fructose on the other hand goes through a different transporter. It does cross from the lumen of the gut into the bloodstream, but it’s not glucose at that point in time. So we don’t necessarily see an increase in quote unquote blood sugar, which is why we would consider fructose to be a slower or a lower glycemic index carbohydrate. What fructose does is it travels through the bloodstream, and it goes into the liver where it’s metabolized by the liver. It has multiple fates at that point, as Dr. You can just pointed out, it can be converted into glucose, it can be converted into lactate, it can be converted into free fatty acids. And as far as I know, and this is definitely a correct me if I’m wrong. The end fate of fructose as determined by the liver has a lot to do with hepatic glycogen stores how much carbohydrate you already have stored in the liver. If you’re consuming a lot of sugary beverages, and you’re not necessarily exercising and your liver is full of sugar, it’s not going to turn that fructose into sugar, it’s going to convert it into the free fatty acids at that point. Now if you are exercising, and your liver is sending because the liver is able to send it sugar stores throughout the entire body, it’s the beautiful thing about the liver, it can keep blood sugar elevated. So if you’re exercising, you’re lowering your blood sugar the liver is depleting itself of its sugar stores. Now this fructose that you’re eating is probably going to be converted into a consumable a lactate or glucose at that point in time. I Am I right?


Trevor Connor  56:32

One other quick thing to add before you jump in Dr. Jeukendrup that’s really important since we’re getting into the physiology understand is both fructose and glucose are processed in glycolysis. But fructose enters in halfway through where glucose goes all the way through glycolysis. And that’s important because the rate limiting step and glycolysis is something called phosphor. Fructose kinase pfk. And fructose enters below that. And so what this means is when you over consume glucose, your body can say, well, I don’t need all this, I’m slowing down glycolysis ago and stored as converted to get into glycogen. Let’s not process it. When if you get a large dump of fructose in the liver, your liver can’t say slow down. It has to process all of it. It has to process all of it at full speed. Because it enters into glycolysis below that rate limiting step. Did I get that right Dr. Jeukendrup?


Asker Jeukendrup  57:29

Yeah, that’s correct. And I think yeah, all of this is a really nice, a really nice summary, I think. And there’s only, like one little point that I would add is that that also a difference between fructose and glucose is glucose goes through the first step. So glycolysis, which is a step that actually cost energy, so you invest energy first to then get ADP out of your glucose. And fructose bypasses that energy step. So you actually get a little bit more ADP because it doesn’t cost as much to break down as glucose.


Rob Pickels  58:03

Interesting, I forgot about that. I know that we don’t necessarily want to sit on this topic for much longer. And there’s so much more information that we can talk about things like how you can manipulate the ratio of glucose and fructose in your fueling to achieve these higher carbohydrate oxidation rates. We can talk about the role of fructose even though we just sort of bash fructose for a little bit, we can talk about the role of fructose in glycogen resynthesis in the liver, and how that improves recovery. Instead of taking another hour of this episode, I’m going to encourage everyone to go back and listen to that episode 83 and 150. Because both of those topics were covered there.


Trevor Connor  58:41

Deserved or not, fructose is the poster child of processed foods. And processed foods aren’t as common everywhere in the world. So let’s hear from Dr. Michael Crowley and how Ethiopian runners approach carbohydrates


Dr. Michael Crawley  58:53

In the rural sort of areas where people start their careers, so because you, for example, were to initiative, barber, and Kenny suffocatingly. And people that that are from, most people said that they ate a diet, which all came from basically the land that they could see from their house to injera that was made with text that was grown locally, all of the food was local, and they didn’t eat anything refined, like pasture or rice or anything like that. So it was when only when they went to the city. And we’re running at a higher level that they kind of adapted to eating rice and pasture and things in terms of the mix of carbohydrates and other things. They were eating a pretty high carb diet when they were training hard. One thing that was interesting was that we have this kind of belief in the 20-minute window after training that it’s really important to make sure you eat something within 20 minutes after training. Usually what we would do is we would get up at 4:30 in the morning, take a bus to training run from about six till about eight o’clock in the morning. Then take a bus all the way back into Addis which would usually take until lunchtime because there was so much traffic and then we’d walk home and then we did something and so we weren’t hitting that window at all and that took me a long time. To get used to that, and I’d be kind of sweating and nearly passing out by the time we got home, but people didn’t see that as a problem, in fact, that was seen as kind of making you stronger to not eat after training. So that was different. But the general sort of eating lots of carbohydrates thing was definitely the same.


Rob Pickels  1:00:17

Trevor, I know, the next big thing on the list is inflammation. So you know, I’d love to because I’m an inflammatory person, as people know, well, I guess my personality is maybe inflammatory, but I have a lot of autoimmune issues. And I think all of this plays together. So Trevor, this is an area that I really want to be educated on. So I love to hear what you have to say on inflammation and carbohydrate.


Trevor Connor  1:00:38

So I’m going to try to give the short version of this my whole thesis in school was on the effects of diet and inflammation and autoimmune disease. So it comes from the guy who actually has an autoimmune condition. I could talk two hours about this. So I’m going to try to be very short, and then let both of you to respond to this. And Dr. Jeukendrup, I’m particularly interested in hearing your response. But I’m going to try to take very complex subject and information and get it down to a couple of minutes. And then maybe you guys can say where we want to go with this. This is the one doctor you can do. I really agree with you that I think a lot of these health impacts that people talk about with simple sugars are mitigated by exercise. But this is one place where I go, actually, and I’ll give some evidence of this exercise makes us worse, and sugar contributes to this. So you need to be careful here. And this is getting into inflammation, particularly in the gut, which was the focus of my research. There’s a ton of studies behind this, if anybody’s really interested, I’m just going to mention one review that just came out last year in 2022. And it’s titled excessive intake of sugar and accomplice of inflammation. And the short version of this. And the other research that I’ve read shows that sugars, particularly when you’re just talking about absorption of simple sugars like sucrose, fructose, and glucose, which is what you find in a lot of drinks. So this, this review talked a lot about sugary drinks, they hit the gut, they can actually be damaging to the gut lining, so they can cause intestinal inflammation, they can cause what’s in literature called intestinal permeability, what people think of is leaky gut, which can allow things that are in your gut to get access to circulation that you don’t want to have access, get into your system. And one of them in particular is something called what you find in gram negative bacteria, something called LPS lipid polysaccharides. This is really important, because this can cause elevation in inflammation. And that’s an extremely complex subject, and actually Dr. Jeukendrup, I really enjoyed. I also read this weekend 2016 study that you wrote, looking at the impacts of high intensity exercise, and carbohydrate diet on inflammatory markers. But what I don’t want to do is get into the two-hour conversation of TNF alpha and il six and all these other things that I’m putting robbed asleep really quickly with. So I’m just going to talk about one which is two types of T cells called th 17, and T regulatory cells. So T cells or T helper cells are what are called the generals of our immune system, they direct the immune system, T regulatory cells have this role of telling the immune system, relax, don’t worry about this, don’t do anything, we don’t want an inflammatory response. So they’re particularly protective of the body. th 17 cells are very damaging cells, we believe they’re their function is when bacteria gets through your gut into your system, th 17. cells, they come in and take care of that bacterial infection. But they’re also really good at damage in your own body. So in a properly functioning immune system, there’s actually a balance between th 17 and T regs. So you get a bacterial infection th 17 comes in, kills the bacteria damages your body and then T regs come in and say okay, now relax, stop. What you see unfortunately, in states of chronic inflammation, which is very common now in Western society is this chronically elevated th 17. And that is necessary for preceding every single autoimmune disease, this imbalance between th 17 and T regulatory cells. But they’re also showing that elevated th 17 can precede heart disease, it can precede cancer, it can precede a lot of diseases. Why this is important, because that review and many of the studies I looked at show that actually this might be the mechanism why simple sugars can have so many impacts and so many diseases, it appears that they identify the mechanism by which sugars, dietary sugars can elevate th 17 and down regulate T regulatory cells and that not only can also have Been an exercise in athletes. But I found a really interesting study as well. There was actually a couple that showed that exercise actually also. So not low intensity exercise, high intensity exercise. So there’s one particular study that looked at people doing in half Ironman, and showed after doing the Half Ironman, you saw a pretty large elevation of th 17. But you saw T regulatory cells get down regulated, and they got down regulated, they were still down regulated, even 10 days after the event. And it has been shown that there is a slightly higher rate of autoimmune disease in high performing endurance athletes, and particularly a higher higher rate of asthma. So, like I said, I’m trying to take a whole lot and put it together. But my one concern about the sugar consumption that you see in endurance athletes is, there’s already this impact you see, in endurance athletes have damaging the immune system just from doing high intensity work. And now there’s research showing that sugary drinks, consuming simple sugars, can also aggravate this down regulate those T reg cells up regulate those th 17. And the concern to me is about the additive effect of the two. So that’s my five minute summary. And I’ll shut up there and allow the two of you in particular, Dr. Jeukendrup in your response.


Asker Jeukendrup  1:06:22

Yeah, I’m not sure I can, I’m qualified to speak to this, really, because this is not really an area of my expertise. We did some studies. But it was mostly looking at the effects of exercise on some of these, some of these changes, not necessarily the effects of diet or sugar intake on markers of inflammation. But I think one of the questions that I have in my mind is from like memory, and one of those studies or two of those studies, we saw that the elite athletes who you would expect, have higher intakes of carbohydrate, and just do this more regularly and have a generally a diet that contains more carbohydrate, maybe also more sugar, they seem to be a little bit more protective than athletes who were not using that. So I’m not sure how sort of that observation gels with what you’re saying. But I’m not that familiar with the literature. So


Rob Pickels  1:07:27

I’ll hop in here, this is an area that I’m actually not very familiar with either, you know, I come definitely more from a performance background and immunology background wherever that you have. And this is an area where me and my head just begins to spin with the complexity that is the immune system. And you know, for me, that’s the thing that I wrestle with, I have autoimmunity issues, I should probably know more about this. But it feels like you know, th 17 is upregulated with sugar consumption. It’s associated with breathing in fine particulate matter, you know, two and a half on the particulate matter of scale. It feels like there’s so much coming from each direction that I as an individual, when I’m thinking about applying to this, I don’t even know where to begin. But if we think about this in sort of a maximal versus marginal gains situation, at the end of the day, whether or not something like this is say driving, and I’m always because I’m so egocentric, whether this is driving my auto immunity or not. It’s an easy thing to do. It’s an easy health choice to make, and to say, Hey, man, I don’t know I maybe I don’t know that taking sugar out of my diet cures my autoimmunity. But I bet it’s not going to hurt. Right. And maybe that’s reason enough to do it right there. Right that there’s no negative consequence to doing this.


Trevor Connor  1:08:46

Yeah. So I mean, Doctor, you raise some of the complexity of this, which I agree with fully and is really interesting. I should mention when your study was fantastic. And just for anybody who’s interested, the title is impact and intensify training and carbohydrate supplementation, on immunity and markers of overreaching in highly trained cyclist. And I did find it interesting. One of your conclusions was that moderate carbohydrate consumption might actually be better, because you saw less inflammation from that without any negative effects on performance, which I really enjoyed. I think some of the what gets is really complicated wasn’t going to bring this up. So I’ll just quickly touch on this is the microbiome. So the bad gut bacteria, and there is a lot of evidence that endurance sports training, particularly moderate or lower intensity training can really improve the composition of our bacteria, which does help the immune system and I can’t find it but there was a really interesting study, read and I’ll put the ball game we’ll put this in the show notes that showed that when you have endurance athletes on a very high, simple carbohydrate diet that tended to push their microbiota composition the wrong way. It pushed them towards a more inflammatory profile of bacteria. And actually what surprised me doctor you can group was you saw a pretty dramatic decrease in their lactic acid producing bacteria which live on carbohydrates. So that kind of surprised me. But those are really when you take a probiotic, that’s mostly what you’re taking, because they tend to be anti inflammatory.


Rob Pickels  1:10:25

So I think, to this point, we’ve had a really interesting conceptual conversation about this. We’ve backed a lot of that up with a lot of the great research that Dr. Jochen group has done. What happens when the rubber meets the road? How do the people listening, Trevor? How do they take this we’re saying simple sugars, man, they’re not healthy for you is that you should have zero in your life, you should have 10 Grit, how does somebody begin to incorporate everything we talked about today into their actual actionable daily lives?


Trevor Connor  1:10:53

Dr. Jeukendrup I’d love to hear from you on this, because I know this is something you’re talking to athletes about all the time.

Sugar Intake in Your Diet

Asker Jeukendrup  1:10:59

I don’t think it is. Like, as far as I’m concerned, it’s really not that complicated. Because if you’re not exercising, I think just follow the general guidelines for healthy eating, which is really reduce sugar intake, ideally below 5% of your energy intake, but definitely below 10%, there’s no need to have more. So try to try to do that with exercise, then you give yourself a little bit more budget to have more carbohydrates, or more sugars in your in your diet, but just follow those guidelines. And the exercise guidelines are, they start usually with the goal, like what’s the goal of your training session, if your training session is just to go out and have fun for two hours, while there’s no need for sugar, right? If performance or the quality of the training session is important. And you want to maintain that till the end, well, then it does become important, and then just follow the guidelines. And those guidelines will say, take somewhere between 30 and 90 grams of carbohydrate per hour, if you’re a professional athlete, maybe you want to push that even higher. There’s no real risk with that, as far as I can see, because you’re going to use almost all of that as fuel. And the little bit that is left over, you’re gonna store afterwards for your next session. So I think that’s generally the recommendation that that I would give. If you want to increase your carbohydrate intake, then look at the quality of those carbohydrates and look for whole grains, for example, instead of refined grains, and you get the benefits of all the nutrients that would otherwise miss out on. So generally, follow healthy guidelines wherever possible, but adjust it when you need sugars to perform.


Trevor Connor  1:12:49

Frankly, I couldn’t agree more with you. And I think that was the message that was coming out loud and clear. And the research that I was reading, looking, the more recent research looking at the impact of simple sugars on an exercise and inflammation. So there was that one really interesting study that I pointed out that finally looked at, let’s look at a high carbohydrate diet that’s low glycemic, versus a high carbohydrate diet that that’s high glycemic, and you really saw the best balance in that low glycemic diet. So that’s a diet, stead of you know, sitting on the couch and drinking your Gatorade and eating your sports food. That’s, as you said, get it through more complex carbohydrates. I’m particularly for me, it’s fruits and vegetables. There was another interesting study that we didn’t even mention that looked at the effects on inflammation and they had athletes do some pretty damaging exercise. But beforehand, before this race, they one group consumed a low glycemic load meal, and the other group consumed a high glycemic load. And what you saw was the group that ate the lower glycemic load meal ended up seeing less of an increase in those inflammatory markers that you don’t want to see rise. So you know, I couldn’t agree with you more. I think it’s focus on those simple sugars when you’re in a race and when you’re doing high intensity work the rest of the time, eat a healthy nutrient dense diet. It’s really that simple. This message of focusing on quality foods is something that everyone we spoke with emphasized to us, let’s hear from Dr. Inigo Mujika, who had a great way of expressing it.

Difference Between Eating for Performance and Eating for Your Health

Dr. Iñigo Mujika  1:14:24

There is a big difference between eating for performance and eating for health. And in terms of getting poor performance, you do what you have to do. But once you are off training off competition, you should switch immediately your nutrition towards eating poor health strategy. And that usually means limiting carbohydrate intake to the max. And personally I think that one of the reasons why the triathletes are right Coach normally did not gain much body mass during the offseason is that my first recommendation was stop carbohydrate. As soon as the offseason begins, try to eat as little carbohydrate as possible and change your focus from a performance nutrition towards health nutrition. So I think that applies to the entire system, in that view can even be applied to the mesocycle. And that can be applied to the micro cycle and that can be applied to the day-to-day nutritional strategies. You can be eating for performance during training in a way. And as soon as you finish your training and you have undertaken your nutrition for recovery, thinking about what is going to happen in training the following day, you can switch your nutritional intake towards it for health.


Rob Pickels  1:16:00

Now, can I ask for clarification when you talk about this reduction of carbohydrate? Is that simple sugar carbohydrate? Or is that including vegetables and other forms of carbohydrate as well?


Dr. Iñigo Mujika  1:16:12

Well, vegetables have a limited amount of carbohydrate in general. So I’m talking about the typical ways of increasing your glycogen levels, which is pasta, rice, potatoes, breads, etc.


Rob Pickels  1:16:28

In module 10, our latest in the Craft of Coaching series, we’re turning our attention to the coaches who are bringing up the next generation of junior athletes. Coaching juniors is wildly different from coaching adults, and applying the same principles often causes young athletes to burn out and quit the sport. Learn how to tailor your knowledge to junior athletes by checking out the craft of coaching at fast talk If you are eating a high quality diet, I don’t think it’s so bad to have a cup of skittles every once in a while. Innately we all know


Trevor Connor  1:17:05

Innately we all know Rob likes the rings and Skittles.


Rob Pickels  1:17:10

I don’t actually I’m not a fruity candy type of person, but other people like Skittles. So for me, you guys are completely spot on. I mean, without question, I can’t even begin to argue or have anything different to say, certainly nothing unique because you stole my thunder. With that said, I do think that it’s okay that people have I don’t want to say freedom in their life. Right? But I don’t think personally, you have a little bit of sugar in your life, you have a little bit of sugar in your coffee is the only sugar you have that day. I live a little it’s probably okay. Should we be having our diet be comprised of added sugars and everything you know, in a lot of people are consuming premade meals, frozen meals, things like that, you got to be really careful about some of the ingredients in there. No, that’s when it goes over the line. But I think that if people are honest with themselves, they know what they should be eating, right. They know that we ought to be limiting the sugars to exercise they know that they’re beneficial there and that, you know, if we’re sprinkling sugar on everything in our diet, we’re probably doing it wrong. So if people are honest with themselves, I hope that they end up in a good place.


Trevor Connor  1:18:17

And one thing I feel remised finishing this episode without saying this to all our listeners because I think this is the biggest mistake that I see athletes make. When you are in a race when you are out doing a hard workout. Gatorade scratch, whatever sports drink you use, they’re fantastic. The better ones are scientifically designed to help you get those simple sugars to your muscles and when your muscles are burning a lot of sugars. But that doesn’t mean that they’re healthy. If you’re sitting on a couch and you’re saying I’m an athlete, so I should be chugging my scratch or chugging my Gatorade or


Rob Pickels  1:18:53

Chugging my never second which I spent about $1,000 on this past week,


Trevor Connor  1:18:54

Then you are seeing the negative effects and you have to be careful about when you are consuming it and when you aren’t dodgy, you can drop any final thoughts for us here. We normally finish with a one minute take on but I feel like we kind of did it. Throw it to you and say what are what are your parting wisdoms to our listeners on this?


Asker Jeukendrup  1:19:18

I think it’s probably a podcast with a really boring message and nothing. Don’t go extreme. Don’t go overboard with your sugar and but also, don’t be afraid it’s not immediately gonna kill you. So it’s yeah, it’s just the normalized message and yeah, people generally find those messages boring, but it’s, yeah, stay away from the extremes.


Rob Pickels  1:19:41

My take home out of this is that we should do a parody podcast that is filled with all the wrong information. Maybe release it on April Fool’s Day. Dr. Jeukendrup, I don’t know if that’s a April Fool’s Day is a big thing in Europe or not. But I think that that is ultimately the take home from this let’s just see if people can find the SAT higher in terrible information because sometimes the good information is just so darn obvious. That’s a good it’s there’s a lot of that information already out there, unfortunately.


Trevor Connor  1:20:16

All right, well, Dr. Jeukendrup, always a pleasure having you on the show. Thank you for joining us


Asker Jeukendrup  1:20:21

It’s a pleasure. Thank you for having me.


Rob Pickels  1:20:24

That was another episode of Fast Talk, subscribe to Fast Talk, wherever you prefer to find your favorite podcasts. Be sure to leave us a rating and a review. The thoughts and opinions expressed on fast talker are those of the individual as always we love your feedback. Join the conversation at to discuss each and every episode. Become a member of Fast Talk Laboratories at to become a part of our education and coaching community. For Dr. Asker Jeukendrup, Dr. Andy Kirklin, Indigo Malika, Michael Prolly, Dr. Indigo San Milan, Neil Henderson and Trevor Connor. I’m Rob Pickels. Thanks for listening!


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