Should I Run On An Empty Stomach?

[00:01] With the rise of popularity in intermittent fasting, you as a runner, because we love to follow trends, right? We’re always trying to do the newest thing, the latest thing to be better than we were before, you may have thought about, is this something that I need to be doing? Can I use this in any way to benefit myself to be a better, faster, more fit runner? Well, I’m Jesse Funk and on today’s episode of Runner’s High we’re going to talk about if you should eat before you go run.

[00:37] If you haven’t spent any time with me here on the channel, hit that subscribe button, you’ll want to stick around, not just because to see my shining face, but also because I interviewed people on my other show, the Smart Athlete Podcast, and we talk about topics like this where we can talk to registered dieticians, people in these specific fields who can answer these questions, not just me doing research and letting you know what I find.

So, now that we’ve got that out of the way, what we want to know is should you eat before you go run? Well, we have to look at the underlying theory here. What are we talking about? Why would we not eat before we go run?

[01:14] I talked about this in another video where we’re talking about stomach aches, well, that’s one reason you might not eat, but in this case, we want to think about performance. And the idea, the theory here is that if you don’t eat before you run, you run in a fasted state.

Say you went to sleep, you got up, you haven’t eaten for eight hours and you go run, then the ability for your body to adapt by burning fat increases over time, and this is something that we’ve seen in scientific literature, in animal models, in numerous places.

But as I was looking for another video I’m shooting today, in my copy of Racing Weight by Matt Fitzgerald, who by the way has been on the Smart Athlete Podcast, we talk about all kinds of stuff in that episode.

I just happened to open the book for whatever reason I had it bookmarked and right on this page, entirely incidentally, I haven’t picked this book up in months or years, probably. Abundant research shows endurance performance is compromised in the fasted state.

[02:22] So, Matt himself is giving us some research to say, maybe this isn’t all though is cracked up to be. And as I’m looking into it more, there are some studies, some human trials, which is this is after Matt’s written the book, that do show some positive effect to fasting and then going running. But there’s a big caveat and that there’s really mixed results in these studies.

And one thing that seems to be conclusive is that if you’re doing a higher intensity run or higher intensity workout, that is typically not beneficial for you to have been fasted before you work out, which goes back to Matt’s point that fasting compromises in durability. That it does not overall give us a benefit. It actually harms us, and there are several different ways that it can harm us. Not just in that workout itself.

[03:23] We always have to be looking at the bigger picture, right? Not just what I’m doing today, but what am I doing tomorrow? What am I doing a few weeks from now? How will I feel? It’s all coming together in a thing we like to call periodization.

If you don’t know what that is, as I mentioned, subscribe to the channel, I have a video on periodization and it explains that. But it’s basically the methodology where we put together our training schedule, the highs, the lows and the intensities, all those varying things coming together in a period ice schedule.

So, the thing with fasting is that it may have no effect or a little effect on our run today. Say I’m just going out for a 45-minute run at long run pace and I’m predominantly going to be burning fat anyway. Well, probably no big deal.

But the effect of fasting has is that it requires you to draw more nutrients from your body, so the higher the intensity of your run, so if you’re going to the track doing intervals on the track or doing a [inaudible], anything with more intensity or a longer duration, anything over 90 minutes, so if your marathon training, then this is especially important for you.

[04:35] Your body’s going to draw newsroom nutrients from somewhere, and when it no longer has the ability to draw on glycogen stores, because even at our long run pace we’re burning fat and glycogen at the same time, it’s just heavily shifted towards fat fuel mix.

At that time, when you are unable to burn any more glycogen, you run out your glycogen stores, at that time then your body is going to start breaking down muscle and that is something we do not want under any circumstances, because then we’d have to do all this extra work to build up the muscle that shouldn’t have been broken apart for a fuel in the first place.

Which leads us to other problems, and that can be injury or a susceptibility to over-training, because what happens because we’re over-trained, right? We are working too hard for our body to recover fast enough to keep up with the training load we’re asking it to go through.

So, if you’ve broken down muscles for fuel, instead of just bringing them down from the exertion in your exercise, in your run, then you’re placing extra strain on your body and the temptation to go into overtrain is going to be greater, or the likelihood of going to over-training is going to be greater because you put that extra demand that your body is unable to cope with, so you recover slower.

[06:07] All of this is really to say fasting may have some benefit. There are, as I mentioned earlier, some studies that show it has some benefit to improving our ability to burn fat aerobically, which is good for us in the longterm, but it is not conclusive. We don’t have enough evidence yet to suggest that it is in fact the way to go.

There’s a lot of anecdotal evidence right now that intermittent fasting is the way to train, is the way to get lean, all of these things. But there is some new evidence coming out suggesting that it may not be all that it’s cracked up to be. Be wary of fats, always be wary of fats.

Now, that isn’t to say that there isn’t a kernel of truth in the things that come out, because we’re always developing our knowledge base, as humans this is what we do, we research, we push the envelope, we try new things. So, it is perfectly fine to look into new things, but look at them with an air of skepticism.

Do your research, look to the trusted experts in fields and see who says what. Is there a plurality or consensus that this is a thing? that this is actually beneficial? Is there enough data to say, “Hey, yes, this is true”? Or is it some kind of pop science article or the author didn’t really understand the study that they were drawing from and drew incorrect conclusions? That happens all the time. And I talk about that with my guests on the smart athlete podcast.

[07:51] So if you want to know straight from the horse’s mouth, speaking to the people doing the research, subscribe to the channel, stick around for my other show, it comes out on Fridays, every Friday. But, for now, if you want to try intermittent fasting, do it in a way where you’re not going to be doing those intense runs right afterwards, at least eat something before you do those intense runs and keep track of how you feel, how your training is going, all that kind of stuff.

Be wary of getting yourself into a situation where you’re going to be injured or over-trained. All right. Well, I’ll see you next time on the next episode of Runner’s High.


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