How do you know that is why he leaves others in the dust, vs him just being more talented, or training more, or training smarter, or just setting higher goals than the last generation of endurance runners?
Also you should keep in mind that while there is at least a plausible story you can tell about > 5 hour endurance efforts benefiting from some kind of fat burning approach, from 5k to marathon, you absolutely want to be burning glucose if you want to go as fast as you can go. This is unambiguous.
In regards to your first point, I mean, in the video, he stated that he used to try running with the glucose packets and he stated that he got sick trying to keep it all down, and it really slowed him down. It's anecdotal evidence of course, but I wasn't trying to present as anything other than that. :-)
Edit: Holy run-on sentence. I'm going to leave it for posterity.
But early on, you don't need to worry much about it, just get out and move every day. If you keep it up for a year or two, and want to get faster, you can start adding things to be neurotic about =)
There are a LOT of other factors. Who's on top in the ultrarunning world is constantly changing, and, the ultra races are extremely vaired: 100 mile road races to the Barkley Marathons.
Just last year, Karl Meltzer broke vegan runner Scott Jurick's Appalachian Trail speed record. Obviously, they had very different diets.
I think the real requirement for ultrarunning (and other long-term thinking activities) is grit. Grit includes will power but also the ability to endure.
Low-ish carb is great. It helps you endure long runs overall and it's a good habit in general. Especially for recovering after the race and getting all those calories back.
During the long run itself however, glucose packets are absolutely necessary. You run out of glycogen stores every 45 minutes or so. That's when you start cramping up and having trouble. A glucose packet gives you some caffeine (helps with stamina and pain tolerance), and some electrolytes (helps with cramping and hydration), and some 100 calories of sugar (helps with glycogen levels and mental fortitude).
Crucially, you aren't replacing all the calories you burn. That's impossible. In a 4 hour marathon I burn between 2500 and 3000 calories. The packets replace only 500 calories.
The difference between packets and no packets is that with packets, I am able to be a human person after a marathon. Far less cranky, far less tired, generally feeling okay. Without the packets, I'm basically a walking zombie.
That said, it took a lot of practice to figure out the right timing for those packets, to train my body to absorb them and so on. It's definitely not something you want to start experimenting with on race day. That's a recipe for puking.
You don't need glucose packets. They might help speed you up a bit, but as long as you've built up your range progressively, the human body can go without them. As I mentioned above, I used to do > marathon distances once or twice a month in the mountains for fun (which I realize is very different than racing. I did dozens if not hundreds of 50k+ runs and have never yet even tried a gel pack. Some of those runs were at a weight of over 90kg!
Yes, you'll burn a ton of calories. I often found I weighed in at a full 5kg less after a run and probably 0.5kg less after re-hydrating. Sure, I was never anywhere near as good at long distances as mid distances, but you don't need gel packs. At least I didn't for anything up to 50k, and I probably could have gone further if not for the logistics of carrying enough water and dealing with the heat and humidity that go along with living on a semi-tropical island.
I used to puke anything I had when I ran.
My digestion couldn't handle food when I was running. It was a mix of slight heartburns (& coffee) causing a sensitive stomach which didn't like food moving around when I ran and partly because I was running so hard my stomach didn't have enough blood to process the food.
Several weeks of eating peanut butter mini sandwiches with their crusts cut off, banana slices and oranges dipped in salt, while running at a moderate pace, I managed to tame the tummy.
That said - I don't think I like the taste of GU gels, but like coffee or beer, you get used to it (& the extra 100Kcal feels like it goes directly to your legs).
Try something like flapjacks or even rice cake [1]. It's more suitable as bike nutrition because of the ergonomics but at the end of the day it's all just carbs.
If you don't like any of that or the solid food is difficult to swallow in a race, you can try just water mixed with maltodextrin. It's a very slight sweet taste.
1: https://www.britishcycling.org.uk/zuvvi/media/bc_files/izone...
Personally, I've switched to mostly liquid nutrition, currently using a custom blend from Infinit. For 6+ hour races, I'll supplment with a PBJ sandwich or a bar of some sort.
And like another person mentioned, it takes some practice to get used to it. A lot of people have trouble digesting anything while running.
I found that just like my legs needed training to withstand a marathon, so did my digestive system need practice to process and retain enough calories. Eating 4000+ calories on a long run day used to be pure torture. But you get used to it.
I can run a 13mi run, and maybe some extra, without gels. Even without water. But in my experience I can't do it for a 20+ mile run.
And my fasted runs are generally slower than nonfasted runs regardless of how I actually feel while running it. For example, when I train every day, my morning runs before a full day of eating are abysmal. My evening runs are nice and fast.
Worse still, when training every day, I've noticed that what and how much I eat the evening before, has a huge impact on my morning run as well. (I tend to do my long runs early in the morning because fitting a 4h run in the evening is tough)
Maybe my problem is the every day training part. It makes nutrition crucial so I can get enough recovery out of my body.
Not to mention the majority of people will feel absolutely terrible trying to run in a depleted state. And there is no good reason to inflict that extra hardship on yourself when you can eat a large carb dinner and have enough glycogen to carry yourself through a half marathon
(Why can this guy still get good results? Ultra marathon is not at all a highly competitive sport. Someone to the far right of the genetic bell curve can handicap themselves with pure fat metabolism and still perform good. They would be absolutely killed in say the marathon distance where there is much higher selection pressure, if you want to call it that. Also, you don't run ultra distance at a high effort level, say 50-60% of VO2max - so here fat metabolism is naturally more pronounced anyway)
And you are always burning fat. Human minds like to break it up into nice progressive steps or state machines but the actual body is just a highly parallel beast. Just that as you get closer to VO2max, the proportion shifts dramatically in favor to glycogen over fat.
Knowing where your walls are ... that's been one of the self-reflection exercises for me. Because it is an extremely personal limit & moves about with weight, food intake, sleep debt, hydration and local weather.
The physical sensation of hitting the wall is somewhat orthogonal to all the other health benefits - it is an extremely accurate read of your physical condition on that day & tells you how you're doing.
The top competitive distance runners (a group dominated by Kenyans and Ethiopians) generally eat over 70% of their calories from carbohydrates. Naoko Takahashi said she loved Korean barbecue. Bill Rodgers, the dominant marathoner of the previous genration, seemed to live off of pizza slathered in mayonnaise. Paula Radcliffe talked about eating a lot of fruits, yogurt and granola. While many, many runners have sworn by various odd diets, it doesn't look like anyone has been able to get a sizable edge from theirs.
I only raced 5-10k ranges, but I used to run greater than marathon distances once or twice per month in the mountains for fun so I can have some personal experience with "walls". Even a skinny person has enough fat on them to run for far longer distances than any race I've heard of. The "walls" are more about glycogen limits in your muscles. Extending the wall is mostly an issue of how high your aerobic threshold is, how well you can spare glycogen at the beginning (though this probably matters less for ultras) and your running efficiency.
All three of these factors are influenced by diet to some degree but training is by far the more important factor. Strangely, caffeine has a bigger effect than macro-nutrient composition.
Here he is making a banana smoothie: https://www.youtube.com/watch?v=96VZFklUM_Q&feature=youtu.be...
This guy: https://youtu.be/96VZFklUM_Q runs ultra marathons, using fat for fuel. He leaves his fellow competitors in his dust because he doesn't have to carry glucose packets to keep his body fed. Instead, he finishes his race with an avocado and bison jerky.