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For decades, Dr. Timothy Noakes and Dr. Louise Burke have debated the best diet for performance, from opposite ends of the spectrum. In a series of new articles, the two nutrition pioneers continue the discussion.
Episode Transcript
[00:00:00] Chris Case: Hey everyone. Welcome to another episode of Fast Talk, your source for the Science of Endurance performance. Today’s episode is brought to you by our friends over at Stages Cycling. Trevor, you bought yourself a little present, didn’t you?
[00:00:18] Trevor Connor: I did, and I just got it last week, so I bought one of the stages, new dual sided, so left right systems and yeah, I mean we talked to Pat about it.
I thought, I kind of understood it when he was explaining it, but it wasn’t until I received it that I went, oh, I fully get it.
[00:00:35] Chris Case: You got two power meters. ‘
[00:00:37] Trevor Connor: cause it’s two power meters. That’s right. Mm-hmm. There is a power meter on the left crank. There is a power meter on the right crank, and I didn’t fully understand that until I got on my bike and I tried to connect and all of a sudden there were three options I could connect just to my right crank.
[00:00:51] Chris Case: Mm-hmm.
[00:00:52] Trevor Connor: I could connect just to my left crank or I could connect to the combination of the two. And I did a five hour ride and probably put my life at risk. ’cause I was spending the whole time just switching back and forth between them having a lot of fun,
[00:01:06] Chris Case: distracted cyclist out on the road.
[00:01:08] Trevor Connor: Well, I wanted to compare.
I wanted to see did they read differently. But relative to my heart rate, it was pretty consistent. I could use the left, I could use the right, I could use the combination.
[00:01:17] Chris Case: Are you imbalanced?
[00:01:18] Trevor Connor: Oh, I’m usually imbalanced.
[00:01:20] Chris Case: Are you
[00:01:20] Trevor Connor: really? My left is so much stronger.
[00:01:22] Chris Case: Oh, I mean mentally. I was talking about mentally imbalanced.
[00:01:25] Trevor Connor: Oh, how many episodes have we been, that has already been answered.
[00:01:32] Chris Case: Yes, correct.
[00:01:33] Trevor Connor: You know, I’m just talking about my experience with it right now. We can certainly go into all the science of the stages, power meter, but it’s really neat and I’m gonna be playing a lot more with this, of having. You know, pure data for your left side, pure data for your right side.
When you use a system that is based in the bottom bracket, not in the bottom bracket, so it’s reading from the chain rings. It has to somewhat estimate whether the power is coming from the left or the right. And there’s always a certain point in the pedal stroke
[00:02:04] Chris Case: mm-hmm.
[00:02:04] Trevor Connor: Where both legs are putting a little power in and it doesn’t know how much each leg is putting in.
So it’s always estimating the left right balance. Here you’re actually getting pure data for left pure data for Right. And to me that’s just, I’m gonna have fun.
[00:02:16] Chris Case: Awesome. Well, stages has always been innovative since the company’s been around the first to measure cadence without a magnet starting with an accelerometer.
Then the gyroscope stages was the first to pioneer the concept of that single-sided power meter. They’ve always been innovative,
[00:02:33] Trevor Connor: they have, and it’s nice to see that they are not resting on their laurels, but continuing to innovate, continue to give us new things that we can try and see with their tools.
[00:02:43] Chris Case: Excellent. Let’s get on with the show. Today we have a doozy. I’m gonna call it a doozy nutrition science between some of the biggest names in that realm of sports science. Dr. Timothy Noakes, Dr. Louise Burke. They published a series of papers, kind of a back and forth, uh, point counterpoint series of papers just a couple weeks ago.
Was it?
[00:03:09] Trevor Connor: Yeah. Just came out.
[00:03:11] Chris Case: Yep. And they represent two sort of polar opposite ends of the spectrum when it comes to high fat versus high carb diets. And there’s a. Pretty lengthy history here, and I’m gonna let Trevor talk about that history. Now,
[00:03:30] Trevor Connor: I’ll give the history, but before I do, anybody who wants to read this, it’s in the American Journal of Clinical Nutrition.
There were actually three papers published. So the, there was a, does a Low Carbohydrate Diet, impede Endurance Sports Performance was the title of all three.
[00:03:47] Chris Case: Mm-hmm.
[00:03:47] Trevor Connor: But then one as is the answer, no. And that’s Dr. No’s paper.
[00:03:52] Chris Case: Yes.
[00:03:53] Trevor Connor: And then there’s one that answers yes. And that’s Dr. Burke’s paper. And then the editor of the journal wrote a short two pager.
[00:04:01] Chris Case: Mm-hmm.
[00:04:01] Trevor Connor: Kinda summarizing the whole argument.
[00:04:03] Chris Case: Yeah. So nos high fat. Burke High Carb.
[00:04:08] Trevor Connor: Yep.
[00:04:08] Chris Case: And they’ve always been that way.
[00:04:10] Trevor Connor: No they haven’t. So here’s the history.
[00:04:12] Chris Case: Yes. Correct. Go for it.
[00:04:14] Trevor Connor: So, and look, if the history of this is a 200 page book, I’ve read 10 pages, there’s a lot that has happened that we know has happened that I am not privy to exactly what happened.
[00:04:26] Chris Case: Oh, sure, sure.
[00:04:27] Trevor Connor: But what I can tell you is, so Dr. Louise Burke, one of the most respected names in exercise science, nutrition.
[00:04:33] Chris Case: Mm-hmm.
[00:04:34] Trevor Connor: She is married to Dr. John Holly. Mm-hmm. Who is also a hugely respected name in the field. And then Dr. Timothy Noakes, also very respected, wrote the lore of running, which is the kind of bible of running.
[00:04:50] Chris Case: Mm-hmm. Long ago.
[00:04:51] Trevor Connor: Long ago. And he’s actually about to release the fifth edition.
[00:04:55] Chris Case: Mm-hmm.
[00:04:55] Trevor Connor: They all, at one point were friends. Mm-hmm. And did a lot of research together. And back in the eighties they were really trying to figure out, you look at it and go. We have very limited carbohydrate stores. We store it in glycogen, glycogen stores there.
There’s enough in your whole body to maybe keep you going for an hour before you’re just gonna start having to rely on other fuel sources. We essentially have an unlimited source of fat, so how do we get the body to be more reliant on fat? And they started doing studies and some quite ingenious studies, really looking at understanding the metabolism of fat and carbohydrate.
Dr. Burke makes this point in her argument that for 70 years the focus of sports nutrition has been on carbohydrates and fats and how you use them and how the distribution changes with intensity, and how you mm-hmm. Make sure you’re using more of one or less of another and optimize each. I mean, that has been the focus of sports nutrition.
But what’s really interesting is at some point. Dr. Nos went, yeah, actually we can perform really well in fat.
[00:06:05] Chris Case: I think he had a bit of a personal moment as well because he, he
[00:06:09] Trevor Connor: became diabetic.
[00:06:09] Chris Case: Correct. And so he was driven in some way to find out more about how he could operate, how he could perform on a high fat diet.
[00:06:16] Trevor Connor: Right. Well, he, and he has said this publicly. We actually did an episode with him. We’ll put that in the show notes. Talking about sugar, the fact that even if it is performance enhancing, high sugar consumption is not good for your health. Mm-hmm. And so he has really been pushing, there is a health consideration here, but believes that you can perform.
On a high fat diet, Dr. Holly and Dr. Burke went the opposite direction, and Dr. Burke did this series of supernova studies where they took race walkers, put them on a high fat diet for three weeks. And then looked at the performance and you saw a drop in performance. And Dr. Holly published, they published multiple papers on that supernova study, and Dr.
Holly titled, I can’t remember the exact title, but it ended with nail in the coffin, basically saying, here’s the evidence that you can’t perform on a high fat diet.
[00:07:13] Chris Case: Mm-hmm.
[00:07:14] Trevor Connor: And there was a real falling out between Nos, Holly and, and Burke. And Burke.
[00:07:20] Chris Case: Yeah.
[00:07:21] Trevor Connor: So that’s the history.
[00:07:22] Chris Case: Yep.
[00:07:23] Trevor Connor: But Dr. Burke and Dr. Nos agreed to have this debate with one another.
Mm-hmm. And just published it.
[00:07:29] Chris Case: Yeah. I would say that the personal history continues on between them. In some sense.
[00:07:35] Trevor Connor: There was some spicy moments in these papers. That’s
[00:07:38] Chris Case: right. That’s, that’s what I’m referring to. That’s what I’m referring to. Yes.
[00:07:41] Trevor Connor: I was reading it with my science hat on and. And one of the rebuttals, I went, whoa, that’s that science speak for fu.
[00:07:52] Chris Case: Those are fighting words.
[00:07:53] Trevor Connor: Yeah. So, yeah, if you wanna read some real contentious science, these are good ones. Have some fun.
[00:08:01] Chris Case: Yeah. But to bring us to these papers, nos actually introduces some new concepts in
[00:08:08] Trevor Connor: Yeah.
[00:08:08] Chris Case: The paper that he wrote. So I think we might start there.
[00:08:12] Trevor Connor: Well, so yeah, let’s give some context.
Let’s go back 5, 6, 7 years ago.
[00:08:17] Chris Case: Sure.
[00:08:18] Trevor Connor: And one of the big arguments, and this was the nail in the coffin argument, is that. You really, once you get to about 85% of VO two max, you are relying solely on carbohydrates as your energy source. And this is what they were showing in the supernova studies is. On a high fat diet, you just can’t do intensity.
Mm-hmm. You can’t go really hard.
[00:08:42] Chris Case: Yeah.
[00:08:42] Trevor Connor: Dr. Notes disagreed with that. Mm-hmm. And one of his arguments was the supernova study was only three weeks. They weren’t fully adapted.
[00:08:50] Chris Case: Mm-hmm.
[00:08:50] Trevor Connor: And you actually saw in those studies towards the end, they were starting to improve in performance. You need to adapt for four to six weeks
[00:08:57] Chris Case: at a minimum,
[00:08:58] Trevor Connor: at a minimum.
And he started doing that research. And this is important in a lab.
[00:09:04] Chris Case: Mm-hmm.
[00:09:04] Trevor Connor: Doing randomized controlled trials. And these are all, I’m, I’m gonna start by saying all three of them are extraordinarily smart. I love reading their studies because they. Their study designs are remarkably sophisticated, really well thought out, and has enabled them to get at things that a lot of other researchers couldn’t get at.
So I, I will give that credit to all three.
[00:09:24] Chris Case: Mm-hmm.
[00:09:25] Trevor Connor: I love reading their research and Dr. Nos, when he had them fat adapt for four to six weeks, showed that actually no, you can continue to rely on fat above 85%.
[00:09:36] Chris Case: Mm-hmm.
[00:09:37] Trevor Connor: And was showing. Rates of fat burning that were beyond what we thought was actually feasible, possible that our bodies could do.
[00:09:45] Chris Case: Mm-hmm.
[00:09:45] Trevor Connor: So he did counter that argument.
[00:09:47] Chris Case: Mm-hmm.
[00:09:47] Julie Young: I think he says up to 90%
[00:09:50] Trevor Connor: mm-hmm.
[00:09:51] Julie Young: Is kind of the ceiling where the fat can keep up with the intensity demand.
[00:09:57] Trevor Connor: And he made the argument. So the way we determine how much carbohydrate versus fat you’re using is by measuring how much CO2, you’re exhaling versus oxygen.
Mm-hmm. You’re breathing in. And he makes the point that not all CO2 that we breathe out comes from the breakdown of fat or carbohydrates. There is some body store, so we overestimate.
[00:10:18] Chris Case: Hmm.
[00:10:19] Trevor Connor: How much we’re aligned in carbohydrates.
[00:10:21] Julie Young: That actually is one of the points they agreed upon. Yep. Was that the gas analysis is not a great way to determine the substrate oxidation.
[00:10:30] Chris Case: I’m glad that there were some agreement in there.
[00:10:32] Trevor Connor: Yeah, yeah. No, and she, she agreed that actually we can, once you’re fat adapted, you can burn a lot more fat than we thought.
[00:10:38] Chris Case: Mm-hmm.
[00:10:39] Julie Young: I think the big difference here is that we’ve accepted that. Or most of us have accepted that it’s the depletion of muscle glycogen leads to fatigue.
And Nokes disputes that he really believes it’s the depletion of blood glucose that leads to fatigue. But I think this is where prior to hitting record, we were talking about how it felt like they were talking past each other a little bit.
[00:11:03] Chris Case: Yeah.
[00:11:03] Julie Young: Because one Burke’s primary fuel source is the muscle glycogen and then depletion of that.
Obviously it makes sense, but if NOS is primary fuel source is the fat in the muscle. T’s really tapping into that and he’s basically saying that it’s the blood glucose. If we can maintain that. And that’s essentially that depletion would be what would be triggering the brain to kind of turn off the effort.
But he’s essentially saying it’s the blood glucose level that would trigger the fatigue through the brain. And he contends that you need to, and again, I think this is not really well stated, but it’s what that fat adapted athlete, so this isn’t to say with that athlete that’s reliant on the carbohydrate, but with that fat adapted athlete.
If they really are tapping into those fat stores in the muscle for their fuel. He’s not necessarily focused on the glycogen stores in the muscle, but more the glucose in the blood. And he contends you can maintain that level of exertion. And again, it’s kind of, he, he states it as sub max prolonged exercise.
With 10 grams per hour of carbohydrate. And that’s essentially all you need. So again, I think the difference here is like Burke is contending, the main fuel source is the glycogen in the muscles and nos is contending. The main fuel source is the fat in the muscle. Yeah. And so that’s where I feel like they’re talking past each other a little bit.
[00:12:31] Trevor Connor: I think it’s really important ’cause this is a real novel concept that everybody listening understand this. So there are two. Glycogen storage locations in our body. There’s our liver.
[00:12:44] Chris Case: Mm-hmm.
[00:12:45] Trevor Connor: And then your muscles, the muscle storage is large, where the liver storage is small. So nos referred to them as the small glucose and the large glucose pool pools.
So SGP and LGP. And one of the just held beliefs for a very long time has been you fatigue when you deplete that muscle, glycogen source, or pool. So we need to keep that stocked up and that requires consuming a lot of carbohydrates because it’s a big pool. So he just, as a matter of fact, one of the studies hasn’t been published yet, I believe, but he’s publishing a few studies where he had athletes deplete the large glycogen pool.
Mm-hmm. In the muscles. Mm-hmm. But then, as Julie said, had them consume just 10 grams of carbohydrate, so that would keep blood sugar levels up that would maintain the small glycogen pool. And showed they didn’t fatigue that they could still perform, and he did everything from one minute efforts to a mile effort to a longer like hour long effort.
[00:13:52] Chris Case: Mm-hmm.
[00:13:52] Trevor Connor: And went. You can deplete that large glycogen pool and they can still perform. They’re not gonna fatigue, which is counter pretty dogmatic science.
[00:14:01] Chris Case: Mm-hmm. So what you’re saying is if you take a fat adapted athlete, specifically a fat adapted athlete, and you have them do a ride or something, where for the most part they’re doing moderate exercise and their fuel source is fat.
And then if you were to have them do some really intense efforts, if they were to have just 10 grams in a given hour. They would be able to go.
[00:14:34] Trevor Connor: He, he is saying they will perform as well. And this is, I have to go back and look at this, but I don’t think he was saying you first have to be adapted to a high fat diet.
[00:14:42] Chris Case: Oh,
[00:14:42] Trevor Connor: I think he’s saying this is in everybody, you can deplete the muscle glycogen storage.
[00:14:47] Chris Case: Mm-hmm.
[00:14:48] Trevor Connor: Or pool. And as long as you are maintaining the blood glucose levels, the small glycogen pool, you’re not gonna bonk, you’re not gonna fatigue.
[00:14:56] Chris Case: That’s crazy to think of because he’s saying 10 grams and everybody’s talking about how Tour de France riders, world tour riders are up to like 120 grams.
Mm-hmm. An hour consistently to maintain what they’re able to do. So those are complete opposite ends of the spectrum.
[00:15:16] Trevor Connor: Right. And so here would be looking at from his perspective, the argument I would give for what you’re seeing with Tour de France athletes. Which is they are burning five, 6,000 calories a day.
[00:15:29] Chris Case: Mm-hmm.
[00:15:30] Trevor Connor: And they need to replete those calories. They just need to get more calories in. Fat is satiating and slows down gastric emptying. Mm-hmm. So if you are trying during a race to consume three, 4,000 calories and you try to do it through fat
[00:15:47] Chris Case: mm-hmm.
[00:15:48] Trevor Connor: You’re gonna have serious digestive issues.
[00:15:51] Chris Case: Yes.
[00:15:51] Trevor Connor: So there is just a practical standpoint of you need to replace calories.
The only way you can replace that much calories. Would be with carbohydrates.
[00:16:00] Chris Case: Mm-hmm.
[00:16:01] Trevor Connor: But I think his argument would be, yeah, you have to replace those calories and the calories are important, but it’s not necessarily what, I think what he’s arguing is it has to be carbohydrates.
[00:16:13] Chris Case: Mm-hmm.
[00:16:13] Trevor Connor: To replenish that muscle glycogen.
I think that’s the argument he’s making.
[00:16:16] Chris Case: I see
[00:16:17] Julie Young: he did do a, a study on rats where he was looking at that small glucose pool and the large glucose pool. And basically what he concluded from that study was the exercise like capacity or ability to perform was reliant on the rat’s ability to increase that small glucose pool, not the large glucose pool.
So totally contrary to what we believe.
[00:16:43] Trevor Connor: Hmm mm-hmm. And you know, interestingly, and people can go to these arguments or his research and read about this, but he now has his 16 lines of evidence showing that it’s the small Gly Jim Pool, not the large Gly Jim Pool. That affects performance. He basically has 16 arguments.
[00:17:00] Chris Case: I see. 16 points. Yeah. Yep.
[00:17:02] Trevor Connor: So I’ll spare everybody and not read all of them here.
[00:17:05] Chris Case: Well give us a taste.
[00:17:06] Trevor Connor: Second line of evidence. Original Scandinavian study linking muscle glycogen and exercise duration ignored key findings of hypoglycemia and high rates of fat oxidization in carbohydrate restricted subjects.
[00:17:19] Chris Case: Mm-hmm.
[00:17:19] Trevor Connor: Point number three, in studies showing carbohydrate improved performance, blood glucose concentrations, degrees, progressively during exercise in approximately 88% of the placebo groups. Carbohydrate ingestion during exercise improved performance 2.7 times more often in studies in which blood glucose concentrations fell in control groups.
So I, I had to think about these for a bit. Basically what he’s saying is. When they were showing fatigue in subjects, they were blaming it on drop in muscle glycogen, but actually what you were seeing was it was the drop in the blood glucose levels that was causing the fatigue. Mm-hmm. Not the muscle glycogen.
[00:17:58] Chris Case: Mm.
[00:17:59] Trevor Connor: And it keeps going, like I said. Yeah.
[00:18:00] Chris Case: Yeah. 16
[00:18:01] Trevor Connor: of those. 16 of them.
[00:18:02] Chris Case: Mm-hmm.
[00:18:03] Trevor Connor: So. It’s very novel. I don’t know if it will pan out, but he’s certainly had some interest in research behind it. And so this is the argument that he’s making is we just don’t need that much carbohydrate.
[00:18:17] Chris Case: I mean, it’s so radically different from what everybody is, everybody at the elite level is doing right now.
[00:18:24] Trevor Connor: Yeah,
[00:18:25] Chris Case: for reasons like you’ve just noted, but that
[00:18:27] Trevor Connor: he is working right now with a lot of fat adapted athletes who are performing very well.
[00:18:34] Chris Case: Mm-hmm.
[00:18:34] Julie Young: Like who? Trevor.
[00:18:36] Trevor Connor: Oh, you’re asking me for names? You know, I’m horrible with names.
[00:18:39] Julie Young: Just give like in terms of sport,
[00:18:41] Trevor Connor: he is working with a lot of triathletes, a lot of Ironman, and this is significant.
Yes, it is. Um, it seems to be a lot of more steady and dur and we’re absolutely, we’re gonna get into this.
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[00:19:13] Trevor Connor: Should we talk about Dr. Burke’s arguments?
[00:19:16] Chris Case: Yeah, I think we need a little spice at this point. So why don’t we talk about Dr. Burke. Not to say that she was just spicy, but she had some strong words in her retort to Dr. Nos. Yeah.
[00:19:30] Trevor Connor: Julie, you made the point. They are completely talking
[00:19:33] Chris Case: past each other.
[00:19:34] Trevor Connor: Past each other, and there’s a lot of that. One important thing to to point out is he’s pointing out this small
[00:19:42] Chris Case: glycogen
[00:19:42] Trevor Connor: pool pool versus the large glycogen pool. As his argument for why a low carbohydrate diet doesn’t impede performance, I would say that’s an interesting point, but I’m not sure that in and of itself completely makes the argument.
[00:19:56] Chris Case: Mm-hmm.
[00:19:57] Trevor Connor: So it is just kind of an interesting new research that he is doing. That’s definitely interesting research, but I’m not sure it’s a complete argument on of itself.
[00:20:05] Chris Case: Mm-hmm.
[00:20:06] Trevor Connor: So, yeah. Dr. Burke’s got spicy in her rebuttal. And this is where I thought personally, it wasn’t a strong argument. She basically said, yeah, he proved all this stuff in a lab.
But lab research is biased and doesn’t look at nuance, and it’s black and white and it’s all kind of bogus and BS and doesn’t translate to performance out in the field. So yeah, he’s done all these randomized controlled trials that are showing these things, but throw ’em all out because they’re in the lab,
[00:20:41] Chris Case: which is odd, just, it’s a lot of things.
But it’s odd because she being a scientist who has done tens, if not hundreds of. Studies in labs and published them as has notes under controlled conditions and so forth, not applied in the quote unquote real world. And that body of evidence completely informs what she does. So to come along and say, eh, he’s done this in the lab, so it doesn’t really matter.
Maybe that’s a simplification of what she’s saying, but that’s a bit unfair, I would say.
[00:21:13] Trevor Connor: I would argue that yes, you ultimately have to prove performance.
[00:21:18] Chris Case: Mm-hmm.
[00:21:19] Trevor Connor: You need athletes who are fat adapted, who are performing well.
[00:21:22] Chris Case: Mm-hmm.
[00:21:23] Trevor Connor: It just really felt she, like she was kind of crapping on the whole exercise science field and saying Anything done in the lab is bs.
And I’m like, you sure you wanna make that argument? You did a lot of lab research.
[00:21:34] Chris Case: Yeah.
[00:21:34] Julie Young: But maybe that’s what she discovered doing a lot of lab research. Like it wasn’t really translating into performance.
[00:21:41] Chris Case: One thing I wanna say, and this is sort of leading into a discussion we don’t want to get to yet, which is the context really does matter.
[00:21:51] Trevor Connor: Her argument ended with. Context matters.
[00:21:55] Chris Case: Okay. Love that. You brought
[00:21:55] Trevor Connor: that up
[00:21:56] Chris Case: a lot. Context words, context matters. The type of athlete or the type of endurance effort matters a lot. The individual matters a lot. Certain people just are quote unquote built differently, and part of them talking past each other is that I feel like a lot of the work that.
Burke does now has to do with cycling, and cycling is very stochastic. There’s a lot of attacks. There’s repeated, intense efforts. Nos, I feel like he’s drawn more towards running and ultra running and triathlons where the effort is far more steady and you’re not tapping into or you’re not utilizing. The quick demand fuel sources that you need to make those repeated efforts, so that really matters.
And then of course, on an individual level, people are. Quote, unquote, built differently and some work better on high fat diets than others do, just based on their DNA.
[00:22:59] Trevor Connor: And I would say that was in her paper.
[00:23:02] Chris Case: Mm-hmm.
[00:23:02] Trevor Connor: Her primary argument.
[00:23:03] Chris Case: Mm-hmm.
[00:23:04] Trevor Connor: Or one of her two primary arguments. One that
[00:23:06] Chris Case: one size doesn’t fit all
[00:23:07] Trevor Connor: that I think was a really strong argument.
There were some points that I think she came down too heavy on in lab studies. They’re not perfect, but I think she came down too heavy. It was interesting listening to both of them go back and forth going, you’re dogmatic and only believe in one diet.
[00:23:23] Chris Case: Mm-hmm.
[00:23:24] Trevor Connor: And then countering with no, you only believe in one diet and they just keep going back and forth like that.
[00:23:29] Chris Case: Yeah.
[00:23:29] Trevor Connor: But she made that point of it’s very individual. I was actually surprised to hear her say, we threw out the high carbohydrate diet decades ago. So she literally said. We don’t recommend universally a high carbohydrate diet, and gave an example of she worked with a Volta cyclist
[00:23:50] Chris Case: mm-hmm.
[00:23:50] Trevor Connor: And worked on helping them to adapt to consuming more carbohydrates.
But she also worked with an alter endurance swimmer who she fat adapted.
[00:23:59] Chris Case: Mm-hmm.
[00:24:00] Trevor Connor: And making that point if it’s very individual and what works best depends on the individual, depends on the context, depends on the event. And I think that was definitely her strongest argument.
[00:24:11] Chris Case: Mm-hmm.
[00:24:11] Trevor Connor: Julia, what’s your feeling?
[00:24:13] Julie Young: I mean, I think it really is so true. It’s all starts with context and that’s what’s aggravating. Kind of reading these arguments, and I’m not a hundred percent sure of this, but I believe this high fat, low carb diet really did start with the ultra runners.
[00:24:29] Trevor Connor: Mm-hmm.
[00:24:30] Julie Young: And to me, when I first started hearing about it, I was like, wow, that makes a lot of sense.
Because they do seem to operate at kind of that endurance, that aerobic intensity. But even within the ultra running. You see, like where I live is the Western states, and some of these top runners are running so fast. So I wonder even within that cohort, do they need carbohydrate because of the intensities that they’re running versus the person that’s just the finisher.
So yeah, there’s just so much context, so much nuance within these to prescribe these things. And as you said, Chris, individuals are so different in terms of how they adapt. I think the one thing in terms of this argument about the scientific practice between the two of them and. Both being critical of each his studies and like I know NOS had said with the supernova, one of his big problems was the lack of randomized controlled trial.
And that these Olympic race walkers, they’re self-selecting. They wanna go into that diet that they know. And that they trust and the bias is the high carbohydrate. Mm-hmm. So I think just as you all said, like there’s been so much publicity on this high carbohydrate diet now, to me it’s the pendulum has swung too hard.
It just based on my experience working with, and I’ll say primarily like the young athletes, like, I think there’s just an overconsumption right now.
[00:25:52] Trevor Connor: I think this is where we’re ultimately gonna go, but I’ll say this now, is I didn’t land. On either side of this argument, I’m somewhere in the middle. I agree with you.
We have gotten carb crazy.
[00:26:03] Chris Case: Mm-hmm.
[00:26:04] Trevor Connor: We don’t need to rely that much on carbohydrates to perform. But Dr. Nos made the argument and, and I think Dr. Burke misinterpreted his argument where he said, once athletes are fat adapted, they can still perform at a very high level. What she said is, well, it’s ridiculous to say that the fuel source doesn’t matter.
[00:26:26] Chris Case: Mm-hmm.
[00:26:26] Trevor Connor: And really kind of hammered on him for that. I don’t think that’s what he was saying.
[00:26:31] Chris Case: Yeah.
[00:26:31] Trevor Connor: I think he was saying, yeah, the fuel source matters, but, and he brought this up, there’s something called metabolic flexibility. You know, this goes back to evolutionary biology. Sometimes in our past, carbohydrates would’ve been available.
[00:26:45] Chris Case: Mm-hmm.
[00:26:45] Trevor Connor: Other times, like in the winter, you would’ve almost necessarily had to be ketogenic.
[00:26:49] Chris Case: Mm-hmm.
[00:26:50] Trevor Connor: And unfortunately you couldn’t go, oh, well, there’s no carbs available, so I’m not gonna go hunt. Yeah, I’m not gonna go gather. I’ll just die. Your body has to adjust. So our bodies have ability to say, okay, here’s the fuel sources I have available right now, I can adjust to be able to perform on the alternate fuel sources.
I agree with him on that. That’s just evolutionary biology and that’s well established.
[00:27:12] Chris Case: Mm-hmm.
[00:27:13] Trevor Connor: But to say that you can perform exactly the same, I would disagree. And one of the things I was surprised neither of them brought up. Was the difference between slow twitch and fast twitch muscle fibers and you brought up events.
When you are going and doing an ultra endurance event, you are almost entirely relying on slow toch muscle fibers,
[00:27:32] Chris Case: right
[00:27:33] Trevor Connor: slow twitch muscle fibers have very limited glycolytic machinery. They’re mostly fat burners.
[00:27:38] Chris Case: Mm-hmm.
[00:27:39] Trevor Connor: So if you’re fat adapted, they’re generally doing pretty fine.
[00:27:42] Chris Case: Mm-hmm.
[00:27:43] Trevor Connor: Fast twitch muscle fibers are mostly glycolytic.
They mostly burn glucose. They don’t have a lot of ability to burn fat.
[00:27:50] Chris Case: Yeah.
[00:27:51] Trevor Connor: I can’t believe that once a fast twitch muscle fiber has depleted its glycogen. That it’s not gonna suffer. And so I actually did some research on that and sure enough, there’s recent research coming from a couple labs looking at depleting muscle glycogen, and that’s what they showed.
And what Dr. Noakes never studied like he did say, yeah, I looked at a one minute effort, I looked at a one mile effort and they performed. But it was a single effort. But my comment was, what about repeated high intensity efforts?
[00:28:21] Chris Case: Yep.
[00:28:22] Trevor Connor: Where the glycogens depleted, and then you’re still relying on those fast switch muscle fibers to keep hitting it hard.
And so I’m looking at one study right now, which is a couple years ago, the role of muscle glycogen content and localization and high intensity exercise performance, a placebo controlled trial, and basically showed that they had these athletes basically deplete their glycogen, then do repeated sprint efforts.
And it had a big impact.
[00:28:46] Chris Case: Yeah.
[00:28:47] Julie Young: And it’s hard to believe like 10 grams per hour of carb could, mm-hmm. Could rescue that situation.
[00:28:53] Chris Case: Mm-hmm.
[00:28:54] Trevor Connor: Yep. And another study, slow twitch fiber glycogen depletion elevates moderate exercise fast twitch fiber activity in O2 uptake. What these studies are showing is once and slow twitch muscle fibers can also deplete their glycogen.
When slow twitch muscle fibers deplete their glycogen, they don’t have a lot, you start relying more on fast twitch muscle fibers.
[00:29:14] Chris Case: Mm-hmm. Right?
[00:29:15] Trevor Connor: Which often aren’t as efficient. Also, and I don’t want to go too deep into the physiology. They show once a muscle fiber starts depleting, its glycogen, you see?
So we use calcium to kind of contract and relax a muscle.
[00:29:31] Chris Case: Mm-hmm.
[00:29:32] Trevor Connor: And you see that mechanism of releasing calcium into the sarcoplasmic reticulum and then being pulled back out starts to suffer. Which means the muscles can’t contract as hard.
[00:29:43] Chris Case: Mm-hmm.
[00:29:44] Trevor Connor: So his argument that depleting the large glucose pool, glycogen pool, these are recent research studies shown?
Yeah, no, actually it has an impact.
[00:29:54] Chris Case: Yeah.
[00:29:55] Trevor Connor: It’s more subtle, but it has an impact,
[00:29:57] Chris Case: unfortunately, for me not to discount these studies. In the end, I feel like they come at it from a very entrenched point of view. They’re trying to find some common ground. I think they do a little bit. Mm-hmm. Nos is bringing some new concepts to the table.
But there’s many nuances to it. I also think that to some degree, particularly Dr. Burke is focused on performance, and I don’t know how many amateurs benefit when they focus solely on performance, because there’s another side to it, which is enjoyment and there’s health, right? General health, right? If you’re talking about.
World tour riders, cycling at the highest level, slamming carbohydrates all day long might be a necessity for your job.
[00:30:53] Trevor Connor: Mm-hmm.
[00:30:53] Chris Case: But that’s not what the average endurance athlete needs to get the most out of their sport, because that kind of sucks. Having 120 grams per hour of carbohydrates is disgusting.
Yeah. Cool. In a lot of ways, and it has repercussions that we have yet to even know about down the line as this sugar consumption skyrockets and the impact it has on general health. Is potentially quite scary, I would say. So I don’t know who they’re talking to exactly. There’s interesting stuff to come out of this argument and counter argument between the two of these great sort of pioneers of sports nutrition, science.
But I do think that some of it is lost on the average endurance athlete.
[00:31:41] Trevor Connor: Really important point here is. UCI just commissioned Dr. Burke’s group.
[00:31:47] Chris Case: Mm-hmm.
[00:31:47] Trevor Connor: To do all that research on what are the recommendations for nutrition, for cyclists.
[00:31:52] Chris Case: Mm-hmm.
[00:31:52] Trevor Connor: And in one of those papers, she did talk about the health impacts and we need to look at that.
[00:31:57] Chris Case: Mm-hmm.
[00:31:58] Trevor Connor: What I have found interesting is. You kind of had Dr. Nokes and Dr. Burke, they started all as friends, I believe.
[00:32:05] Chris Case: Mm-hmm.
[00:32:05] Trevor Connor: Then there was a falling out and very polarized.
[00:32:09] Chris Case: Points of view.
[00:32:10] Trevor Connor: Points of view. And you are now seeing, even though they still seem to really wanna argue with one another, a sort of coming towards the middle of both of them.
And she pointed this out and this is where she actually won. Some of the argument, ’cause remember the argument is simply here, can you perform as well on a high fat, low carbohydrate diet?
[00:32:33] Chris Case: Mm-hmm.
[00:32:34] Trevor Connor: And he did. And she points us out. He did say, so as you’re consuming 10 grams of carbohydrate per hour, and she went.
You just said it right there. You can’t perform unless you’re consuming some carbohydrate.
[00:32:45] Chris Case: Mm-hmm.
[00:32:46] Trevor Connor: His argument is it’s a low level of carbohydrate, not the 120 grams.
[00:32:51] Chris Case: That’s right. Yes.
[00:32:52] Trevor Connor: And I think that’s the important point is he’s kind of admitting, yeah, you need some carbohydrates.
[00:32:57] Chris Case: Mm-hmm.
[00:32:58] Trevor Connor: But I think the good point he’s making is that you’re also bringing up is.
Do we need the 120 grams per hour? Mm-hmm. And there is evidence like the depleting muscle glycogen. It isn’t as black and white as we thought.
[00:33:10] Chris Case: Mm-hmm.
[00:33:11] Trevor Connor: That maybe we’ve gone too far in that direction.
[00:33:14] Julie Young: No, I agree. I think, like I said, I think the pendulum has swung super hard. It’s so much of this. I know we’ve had experts on the show and they’re aghast at most of the.
Guidance is coming from social media. Mm-hmm. And it’s hard ’cause again, like so much publicity on what these world tour riders are doing, the Tour de France riders, I mean, that’s such a unique event. And as I’d mentioned, like what I’m seeing with these young junior mountain bike riders that I coach, it’s ridiculous the amount of rice they’re ingesting, the amount of carbs they’re trying to push towards a 50 minute race.
And it’s interesting, I just read this. Paper, it was Morton, you know, the, the London Marathon and mm-hmm. I think at least two of those renters broke the two hour mark.
[00:33:58] Chris Case: Yeah. Two of them did. Yes.
[00:33:59] Julie Young: Yeah. So Morton was the nutrition company that was helping them with their nutrition strategy Yes. Going into that race.
[00:34:06] Chris Case: Yep.
[00:34:06] Julie Young: It was really interesting. So the winner won by 11 seconds and he had a really well established fueling
[00:34:15] Chris Case: mm-hmm.
[00:34:15] Julie Young: Protocol and stuck with it. And I, I think he ingested like 115 grams per hour. Of carb and the guy that got second 11 seconds back faltered a little bit in that fueling strategy, and I think he ended up taking in 59 grams per hour.
But it just shows, I mean, 11 seconds and the difference in that ingestion.
Mm-hmm.
[00:34:36] Julie Young: And they also did this, like you had mentioned, I think Trevor, about this idea of analyzing the CO2. Mm-hmm. And they’re, they’re using the c stable isotope to really understand how much exogenous carbohydrate you’re utilizing.
And you realize, oh my gosh, it’s wildly different. From individual to individual, even within the same event.
[00:34:57] Chris Case: Mm-hmm.
[00:34:57] Julie Young: So I think it’s just, again, the pendulum swung hard. We’ve accepted this, everybody’s jumping on board, and now I think it needs a reexamination.
[00:35:05] Trevor Connor: Yeah. So. Should mention this and for anybody who’s interested, Dr.
Paul Larson on his podcast just did an interview with Dr. Nos.
[00:35:13] Chris Case: Mm-hmm.
[00:35:14] Trevor Connor: And, and talked a lot about this science. And in that interview, Dr. Nos talked a lot more about that concept of metabolic flexibility. Mm-hmm. And I think this is important here, and we will do a full episode on this at some point. I love this research.
So we talk every once on the show about A MPK. A MPK is what’s called the energy sensor in our cells, and it basically detects the glucose levels in our blood and that impacts stage of life, essentially, that a cell is in.
[00:35:47] Chris Case: Mm-hmm.
[00:35:47] Trevor Connor: So when glucose levels are high. Cells go into cellular reproduction, so go into cell growth, which sounds great and sounds like something you want all the time.
But an interesting thing is cancer cells. Mm-hmm. Which don’t like to die and like to reproduce.
[00:36:02] Chris Case: Yeah.
[00:36:03] Trevor Connor: Actually create a high glucose environment around them to keep Yes. A MPK deactivated. Mm-hmm. So not something you want all the time.
[00:36:11] Chris Case: Yeah.
[00:36:12] Trevor Connor: When. Glucose levels are moderate cells go into something called cellular senescence, or basically maturity that if it goes too long, goes into senescence and senescence is not something you want.
[00:36:24] Chris Case: Mm-hmm.
[00:36:25] Trevor Connor: When glucose levels are really low. Then you go into all faci, which is program cell death.
[00:36:31] Chris Case: Mm-hmm.
[00:36:32] Trevor Connor: Which you actually want because the cells need to be replaced. You want to go through all three of these cycles. You want times when you are consuming more carbohydrate. You want times when you’re consuming less carbohydrate.
And trying to stay in one state all the time isn’t good. And yes, I did look this up. There is research coming out showing that endurance athletes who are consuming carbohydrates all the time do seem to have higher rates of cancer.
[00:36:56] Chris Case: Hmm.
[00:36:57] Trevor Connor: So I’m not making the argument for you should be on a keto diet because.
Keto diet pushes, cellular senescence pushes autophagy, and there is also research showing that you see more rapid aging on a long-term ketogenic diet. So the argument here is the flexibility. You need to have phases of all
[00:37:17] Chris Case: in a general sense. Those two points, those two things are on opposite ends of the spectrum, and we kind of know that.
Going to the extremes is usually not the best method. So having something in between diversity of states that you are in, sometimes at one extreme, sometimes at the other extreme perhaps, and, but a majority of time somewhere in the middle floating is possibly just the most generally healthy and. Pretty damn good for performance most of the time too.
[00:37:49] Trevor Connor: Yeah,
[00:37:51] Julie Young: yeah. But we seem to be drawn to thick streams.
[00:37:53] Chris Case: Well, some people do.
[00:37:55] Julie Young: We like that.
[00:37:55] Chris Case: Some people seem to be, and then other others are far more skeptical, and I think that’s a pretty good way to be, too. Yeah.
[00:38:02] Julie Young: Yeah.
[00:38:03] Chris Case: I think all three of us are pretty skeptical people, aren’t we?
[00:38:06] Trevor Connor: Well, I think that’s the key message, and sorry, we’re giving more of our bias now on debate.
I don’t think long-term super high carbohydrate particularly. ’cause you only to eat that much carbohydrate. You’re having to eat sugar, you’re having to eat a lot of processed food.
[00:38:22] Chris Case: Yeah. So let’s get back to the studies and wrap up our points here. What else can we bring out of the studies themselves or these papers I should say?
That are relevant to our conversation today.
[00:38:36] Trevor Connor: Well, Julie, you raised this before we started recording of probably Dr. Burke’s strongest point
[00:38:41] Julie Young: in that the carbohydrate is a more efficient fuel.
[00:38:45] Trevor Connor: Yeah.
[00:38:45] Julie Young: In the amount of oxygen required to produce the A TP. And that’s where I think, you know, she says, and no says, you know, up to 90% of VO two, it’s an equivalent fuel, but then at that point you have to sacrifice power or speed.
[00:39:01] Trevor Connor: So it’s, it’s a really good point of we can only consume so much oxygen and. Fat needs more oxygen compared to carbohydrates for each molecule of a TP that it produces. So at high intensity
[00:39:15] Chris Case: mm-hmm.
[00:39:16] Trevor Connor: You just can’t produce as much a TP on fat.
[00:39:18] Chris Case: Mm-hmm. We don’t normally do take homes on a episode like this, and I get the sense that we kind of all are thinking about this in a similar way.
Where do you land on this, Trevor?
[00:39:30] Trevor Connor: I’m gonna start by saying we didn’t cover all of it. There was a lot in these arguments. Mm-hmm. It’s, it’s worth a read. It’s really interesting. I’m guessing here, I don’t think any of us landed on one side or the other. I think we all landed somewhere in between.
[00:39:44] Chris Case: Oh, definitely.
Yeah. I feel like they’re maybe on the extremes at either end of a spectrum, and it’s not applicable to most of the people that are listening to our show. That’s making an assumption, but I, I just don’t think that a massive. Amount of carbohydrates is necessary for the typical amateur athlete to do a sport with enjoyment.
Yeah, they might not be at their absolute best. But do they need to be, and do they want the side effects of all of that carbohydrate consumption to go along with the 0.5% boost that they might get if they train their guts to consume all of that? And then on the other hand. For certain population of athletes, a high fat diet could actually be great with some supplementation of carbohydrates at maybe strategic points in the race or what have you.
But I think that the ketogenic diet long term. Also has considerable flaws and it’s hard to do. I think it, most people don’t understand that I don’t understand because I’ve never even tried it. I’ve never done it, I should say, but I think it’s a hard one to maintain. So I feel like for those reasons, it’s also at an extreme, somewhere in between.
Is gonna work for the majority of people, it’s gonna work really well for the majority of people. It’s gonna be healthier in a lot of ways for the majority of people. So while this is a very fascinating debate that continues between these particular individuals and they are advancing the science of nutrition in a lot of ways that may trickle down to the average athlete someday.
I feel like a lot of this has to do with personal points of view and. Stakes in the ground that they’ve made long ago that they feel like they must maintain in some way.
[00:41:44] Trevor Connor: You know what I would add to that is I think Dr. Nos has served an important role of challenging a lot of the dogma that’s out there.
[00:41:53] Chris Case: Mm-hmm.
[00:41:53] Trevor Connor: He’s clearly ruffled feathers.
[00:41:55] Chris Case: He’s been doing it for a long time,
[00:41:56] Trevor Connor: doing it for a long time. But I think it’s an important role to challenges. Carbs are supreme.
[00:42:02] Chris Case: Yeah.
[00:42:03] Trevor Connor: And to say, no, actually you can perform. Pretty well on, on fat, but I’m not gonna go as far as to say you can perform just as well.
[00:42:12] Chris Case: Mm-hmm.
[00:42:13] Trevor Connor: I’ve still seen the evidence that when you are doing, like in a cycling event, repeated high intensity efforts
[00:42:20] Chris Case: Yeah.
[00:42:21] Trevor Connor: That you can do that glycogen depleted, so. As you pointed out, he’s looking more at people that are doing steadier longer distances.
[00:42:29] Chris Case: Mm-hmm.
[00:42:30] Trevor Connor: So I think it’s just creating very important nuances and I was very happy to see Dr.
Burke say. We don’t recommend the high carbohydrate diet anymore.
[00:42:40] Chris Case: Mm-hmm.
[00:42:41] Trevor Connor: Yeah. That, that’s old news. We are now much more about individuality.
[00:42:44] Chris Case: Yeah.
[00:42:45] Julie Young: And that’s been for a bit of time, hasn’t it? Like, as opposed to that really static. Every single day you do this much carb, this much. I mean, now there, the periodization has been around for a bit of time.
But I think that was well said, and I just think at the end of the day, it’s all about the individual and it’s about the context. What’s the event, what’s, or is it an event? Is it more health related? Within that event, what are the demands of the event? What’s your level of competition Think? At the end of the day, it’s just thinking for yourself and trying to find good sources of information, but really thinking for yourself and applying again, what makes the most sense for you, depending on your goals.
I do feel like these two are talking to different groups of people, though I feel like NOS is more in that ultra endurance and Burke is more that high intensity type athlete.
[00:43:33] Trevor Connor: Yeah, and this is where I’m gonna be the really friendly Canadian and just say. I, I don’t know the source of the contention.
[00:43:41] Chris Case: Mm-hmm.
[00:43:41] Trevor Connor: The personal contention. I would love to see both get over it because they are both brilliant researchers who put out great studies. To be able to get them to work together again to, to find these nuances would help the exercise science world so much.
[00:43:58] Chris Case: It’s amazing that you can draw such different conclusions, even though you’re doing.
As you put it, brilliant science, whether it’s in a lab or in the field, they’re coming down in very different places. Yep. That was another episode of Fast Talk. Subscribe to Fast Talk wherever you prefer to find your favorite podcast. And don’t forget, we’re now on YouTube, so give us a like and subscribe to our channel there.
As always, remember that the thoughts and opinions expressed on Fast Talk are those of the individual. Join us on social media at Fast Talk Labs for access to our endurance sports content and continuing education. For coaches, head to Fast talk labs.com. For Julie Young and Trevor Connor, I’m Chris Case.
Thanks for listening.
