Peter Frick-Wright (host): This is the Outside Podcast.
Peter: One of the first events at this year’s summer olympics is race walking. On August 1st, the fastest walkers in the world will toe the line to see who can move the quickest while keeping one foot in contact with the ground at all times and straightening their leading leg as the foot makes contact with the ground and keeping it straight until the leg passes under the body.
And I know you’ve heard the jokes and seen the parodies, but… race walking is hard core. Elites walk a 6 and a half or 7-minute mile for 20 km. It’s a sport whose athletes live at the limits of endurance and pain tolerance.
So, with the summer olympics in Paris coming up, we thought we’d replay this episode from 2019 about an Olympic race walker who signed up to participate in a nutrition study that changed his life.
It’s the first of three episodes we’re doing looking at interesting aspects of this year’s Olympics. It was originally produced as part of our Sweat Science series.
Peter: In the beginning, there were carbs, and they were good.
Alex Hutchinson: It’s just inextricably connected that if you want to enhance your endurance performance, you have to carbo load.
Frick-Wright: Runners run on carbohydrates. For the last half century, the menu for athletes has been pasta, bread, rice, and potatoes.
Hutchinson: It’s like carbohydrates and endurance are the match made in heaven.
Frick-Wright: But then there was fat, and some said, it was better.
Hutchinson: In the sports world, it was in ultra running that people first started to say, Hey, I think it’s better to just go on a low carb high fat diet.
Frick-Wright: The idea was that if you could tap into your body’s nearly endless supply of fat, use it to fuel your workouts, you’d have basically an unlimited supply of energy. You could run forever. And then athletes started going out and doing it. In 2012, Timothy Olson broke the record at the Western States 100, a trail race in the Sierra Nevada mountains. Then in 2015, Zach Bitter beat the American record for a hundred miles running on a track and eating a diet almost completely free of carbs.
Hutchinson: It’s just totally radically rejecting everything we thought we knew about sports nutrition.
Frick-Wright: This is Outside Sweat Science columnist Alex Hutchinson, and he was and still is covering the low carb high fat diet as it’s surged in popularity. Now it’s known as the bulletproof diet, paleo, caveman, Atkins, or the ketogenic diet. They’re not exactly the same, but they all limit carbohydrates and reject the idea that carbs should be the foundational block of the food pyramid.
Hutchinson: So it becomes this sort of, the man versus the counterculture of — they want you to believe that you need carbohydrates, but in reality you can set yourself free by following this new diet.
Frick-Wright: You’ve probably heard of at least one of these name brand diets, or have a friend who stopped doing carbs at some point. And for people with certain food sensitivities, dropping carbs can actually feel like a miracle cure. And in the weight loss world, this idea has been pretty popular since the two thousands, and because so many people are seeing such great results, there’s a long standing debate about whether cutting carbs is the fastest way to lose weight and cash in on all sorts of internal health benefits.
Hutchinson: Or is that going to, you know, give you cancer and make your head fall off and do all sorts of other bad things.
Frick-Wright: What is new, and still very much up for debate, is whether or not a low carb, high fat diet is actually a superior nutrition plan for endurance athletes, or just an alternative.
Hutchinson: So then we’ve got this new layer that’s not just is it good for you, but will it make you run a faster marathon or do better in your triathlon or whatever the endurance challenge that you’re contemplating.
Frick-Wright: So today we’ve got the story of one man who was faced with an endurance challenge and was propelled to completely new heights thanks to a low carb, high fat diet, but maybe not quite in the way that proponents of the diet would like you to believe. That man is 28 year old Canadian Evan Dunfee.
Evan Dunfee: My name is Evan Dunfee.
Frick-Wright: The sport?
Dunfee: I’m a Canadian race walker.
Frick-Wright: Race walking.
(audio from race walking broadcast): But what we see you so often is a one or two walk is going out fairly fairly fast, but then they tend to drop back.
Frick-Wright: Evan Dunfee has dedicated two thirds of his life to the sport of racewalking, but he still has to explain what it is.
Dunfee: Everything is the exact same as running; the aerobic components that are necessary, all that stuff is the exact same as running. The only difference is that in race walking, we have to adhere to two rules: one foot always has to remain in contact with the ground; and your front leg has to be straight at the knee from the time it touches the ground until it passes onto your body.
Frick-Wright: If you can’t picture it, imagine elite athletes trying to run but as politely as possible with their head back, perfect posture, arms pumping, hips on a swivel. And yes, it seems kind of weird artificially make yourself slower and still call it a race. But if you think about it, that’s how swimming works too
Hutchinson: Race-walking is like that. It’s like an out of the water version of swimming where form absolutely predominates everything. But you also have to be pushing to your physical limits.
Frick-Wright: So you can think of race walking as the breaststroke of track and field.
(to Dunfee) And how fast are you going? What’s an Olympic speed for a race walker?
Dunfee: My personal best time for 50 kilometers is 3 hours and 41 minutes and 36 seconds. So roughly a 4 minute and 26 second kilometer.
Frick-Wright: For those of you unfamiliar with the metric system, that’s fast.
Dunfee: It would be slightly quicker than a seven minute mile. For perspective, I know the marathon is something that a lot of people can relate to. So in 2017 I walked the BMO Vancouver marathon, and walked it in 3hours, 10 minutes and 32 seconds.
Frick-Wright: If you’re not a runner or don’t know marathon times, a three hour marathon puts you in the top 2% of everyone that runs marathons. You can qualify for Boston at three hours, five minutes. Evan nearly walked that. And the longer the race goes, the better he gets.
Dunfee: The 50 K is my primary event. I like the longer stuff. I wish there was an even longer event.
Frick-Wright:50 K is about 31 miles, so it’s a quintessential test of endurance, a marathon plus a little bit, and Evans always sort of gravitated to the more drawn out athletic events. As a kid he struggled at stick and ball team sports. He was an average runner and only took up race walking when his older brother had his appendix removed. He couldn’t take the impact of running. But Evan had a knack for low grade sustained effort. So pretty soon he was a really good racewalker. He set provincial records and then the Canadian under 18 record and then qualified for the Commonwealth games. Every year, he kept getting better, until it came time for the Olympics in London 2012 which is when he realized that when you start competing against the best in the world, he was kind of average — middle to back of the pack. He didn’t even make the Canadian team.
Dunfee: I guess more than anything, I just kind of lost sight of how much hard work it actually took and took for granted getting better and better and better. When I didn’t improve for the first time was just kind of shocking more than anything else. And it was just sort of unexpected and it really rattled me. It took sort of that reaffirmation to be like, this is actually something I really want to do and it should be hard. If it’s not hard, then it’s not really worth doing. I think that that moment in London really helped solidify a bunch of those thoughts.
Frick-Wright: He set his sights on the 2016 Olympics in Rio de Janeiro, Brazil, which meant getting serious about his training, which in 2012 meant going to Canberra to train at the Australian Institute of Sport.
Dunfee: My teammate Inaki Gomez had gone down in 2011 and come back and was just like, this is amazing.It’s three months of summer when it would be winter otherwise. So for that reason alone, it’s great. The training environment, the people, the infrastructure there. It was just so new to us and something that we had never even really imagined existed.
Frick-Wright: He trained with the best race walkers in the world, including Jared Talent an Australian who’d two medals in London, and he worked with Louise Burke, head of Sports Nutrition at the Institute.
Dunfee: And so from there, I started going back pretty much when every opportunity I got. And then in the winter of 2015, Louise Burke and Jared got in touch and said, Hey look, we’re doing this supernova thing, looking at the effects of a high fat diet. Would you want to come out and do it?
Frick-Wright: If you want to study how fuel affects endurance, race walking is an interesting sport to look at. And the reason why it has to do with how muscles can switch between types of fuels.
Hutchinson: So there are three macronutrients: protein, fat and carbohydrate. And when you’re talking about endurance performance, protein, we can mostly ignore it. So it’s either fat or carbohydrate, and there’s been well over a century of research trying to figure out which fuel dominates, which is more important, how the body decides what to burn when.
Frick-Wright: In general, when you’re doing easy exercise, like walking or on a light jog, you’re burning fat. But as you speed up, the body starts drawing more and more from carbohydrates, which it turns into glucose. That’s because before the muscles can actually use fatty acids or glucose, both have to be turned into something called adenosine triphosphate or ATP. You can think of fatty acids and glucose as different kinds of crude oil and ATP is like gasoline, the thing your engine actually runs on. You’ve got a virtually bottomless supply of fat, but the process of refining it to ATP is simply too slow to keep up with your muscles’ needs when you’re really pushing hard — you can make ATP from carbohydrates twice as quickly. That’s why as the intensity of your workout increases, your body starts switching to carbohydrate.
Hutchinson: So you’ve got this variable fuel mix that goes from virtually all fat to virtually all carbohydrate depending on how intensely you’re going.
Frick-Wright: The exact mix for any given effort depends on a bunch of things including what you eat. So if you eat more carbohydrates, your body gets better at burning carbohydrates.
Hutchinson: And the more fat you eat, the better your body gets at burning fat. This is well known, has been known for a long time, studies going back a century.
Frick-Wright: So sports scientists have known for a long time that at top speed, we’re mostly burning carbs. But then in the nineties researchers started looking at whether or not you could prime the body to burn fat more quickly by giving it only fat. The theory was that by denying your body carbohydrates in training, you could force it to rely more on fat. Then in a race, you wouldn’t need to tap into your precious and limited supply of carbohydrates until the finishing sprint.
Hutchinson: From about, let’s say 1995 to 2005, this was a huge area of research in sports science, but it just never produced the results that people expected. No one could demonstrate that it was actually better than the usual approach and around 2005 people finally figured out that if you eat a high fat diet, not only do you get way, way better at burning fat, you also get worse at burning carbohydrate. In fact, your body kind of throttles your ability to burn carbohydrate, and this is a problem if you’re a competitive athlete because it means you’ve got no finishing kick.
Frick-Wright: In 2005, a definitive study at the University of Cape Town showed that cyclists were significantly worse at mid race sprints and surges after spending time on a high fat diet, even when using carbs for the actual tests. And for the most part that was that without carbs you didn’t have any explosive power. So everyone pretty much decided that high fat diets aren’t right for most athletes. But the thing is no one really told the athletes. They kept experimenting with cutting carbs and they seemed to like the results.
So even after having declared the 2005 cyclists study to be the nail in the coffin of high fat diets, Louise Burke at the Australian Institute of Sport started to look for ways to test it out again. And she thought maybe you could apply the diet to an activity where there was no sprinting. What if there were an endurance sport where a brisk walk was as fast as you ever went?
(audio from racewalking event): Dunfee, who’s been working so tremendously hard training in Switzerland — he’s been working with a psychologist and he’s somebody who has a degree in kinesiology. So he knows about human physiology as well as anything else.
Frick-Wright: (to Dunfee) And what was your like nutrition game plan like before that — had you ever heard of the high fat diet?
Dunfee: I had heard bits and pieces of it through my degree. My diet at that point, and probably still now, is one of those things that’s probably in the like big things that could change for the better. Training 200 kilometers a week kind of provides me an opportunity to make the excuse that I can have more donuts. And so for me, going into supernova, it was a radical change cause I basically lived off of sugar.
Frick-Wright: The supernova experiments began in the fall of 2015. Evan joined 19 other elite race walkers in Australia and the plan was to divide them into two groups, restrict the carb intake of one of the groups for three weeks, and see if their bodies could adapt to run on fat. All their meals would be prepared for them and they would try to force their bodies to adapt, no matter how much it sucked.
Dunfee: It was awful. For those first couple of days– that first time that I just had nothing to compare it to.
Frick-Wright: Physically, the workouts were grueling. Even the ones that were supposed to be easy. Evan’s heart rate was higher, his times were slower and he felt terrible. But there have been several studies going back to the 1930s that have shown that with long enough to adapt, your body can run on fat. And Inuit cultures traditionally lived on what was essentially a low carb, high fat diet. But that doesn’t mean it’s easy to switch. Your body will do everything it can to convince you to take in more than the 40 grams of carbs Evan Dunfee got each day.
Dunfee: So 40 grams of carbs is nothing — that’s two medium sized bananas, I guess.
Frick-Wright: The first step of each training session was hard and Evan said it never got any easier.
Dunfee: My teammate Inaki Gomez, who’s like this stoic, strong character, after one of his long walks just ended up collapsing down beside one of the vans and just broke out into tears. And it was just inexplicable, like he didn’t know why he was doing it. He couldn’t understand why it was happening, but like it was just so emotionally draining trying to get through that training in those first couple of days, that first week.
Frick-Wright: Mentally, it was also grueling. The supernova study had both a high carb and a low carb group and they ate their meals right next to each other.
Dunfee: You sit down for your pasta dinner, which was zucchini pasta with a carbonara sauce. And you’re looking at this bowl and your bowls a third full and instinctively you know that you’re getting the same number of calories as the person next to you. But you look at the person next to you and they had this overflowing plate of pasta and bolonaise sauce and and even though, you know, it’s the same number of calories, it just can’t convince yourself of that. So you’re watching these guys eat and you’re just getting depressed and depression in the lightest sense of the word was an overarching feeling that a lot of guys had.
Frick-Wright: But over the next few weeks as they continue to work out and eat fat, their bodies did start to adapt. In fact, they basically became fat burning super ovens, torching it faster than any of the researchers expected. 1.57 grams per minute at the end of a time trial. That’s like burning a half pound of fat every two and a half hours, and as they adapted, the workouts started to feel a little bit easier. Instead of being totally grueling, they were just hard and unlike a normal workout, they didn’t get any harder at the end.
The reason for this has to do with how your body portions out energy. Carbohydrates are stored in your muscles as glycogen and you’re carrying about 2,500 calories worth of glycogen around with you at any given moment. You also have another 400 to 500 in your liver, but that’s getting into the weeds. Anyway, if you’re running around burning through your glycogen, you start getting near the end of those calories, like at the end of a workout, your body starts to complain. It hoards resources, tells you you’re done. Tries to convince you to stop and then finally you do, you bonk, because your body really doesn’t want you to get to the
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