135. The Benefits of Becoming Metabolically Flexible

My name is Patrick McGilvray, and I’m an experienced marathoner, ultra runner, Sports Nutritionist, Master Life Coach, and weight loss coach for runners. I’ve dedicated my life to helping runners just like you properly fuel your body and your mind. So you can get leaner, get stronger, run faster, and run longer than you ever thought possible. This is Running Lean.

Hey there, and welcome to episode 135 of Running Lean. My name is Patrick McGilvray, the weight loss coach for runners and today, the benefits of becoming metabolically flexible. As a runner, you’ve probably been told that if you want to avoid hitting the wall, you need to consume a whole lot of one type of fuel: sugar basically, right?

And this approach does work for some, but for others, it spells metabolic disaster leading to incessant weight gain, insulin resistance and a host of other health issues. If you fall into this latter category, you may want to consider becoming metabolically flexible. Metabolic flexibility means you’re able to use multiple fuel sources effectively, this approach will help you lose weight, run longer and run faster.

So in this episode of the podcast, you’ll learn exactly what metabolic flexibility is, you’ll learn all about the benefits of metabolic flexibility. And I’ll show you how to get started with it. And you have to understand something: metabolic flexibility is not a one size fits all type of solution.

Okay, this does not work the same for everyone. Everyone’s a little bit different. We all have our own goals, we all have our own metabolisms, we all have our own likes and dislikes. You know, we all have our certain food preferences, body types, genetics, all these things factor into how we approach nutrition from an athletic performance standpoint, and metabolic flexibility, you know, choosing different sources of fuel for different types of activities is going to be the same it’s going to, it’s going to be different for every individual.

Okay, this is one of the reasons why I created the Running Lean coaching project. This is my immersive coaching program. And in my program we work together. So I work with you as an individual to help you come up with a personalized plan that works for you. You want to become metabolically flexible, you want to become more efficient at burning fat, you want to, you know, lose weight, you want to get faster, you want to be able to run longer than you ever have before.

All these things require some level of metabolic flexibility is what we’re talking about on the podcast here today. But also, if you want to take things a step further, and you want a little help with this, then consider joining the Running Lean coaching project. And what we do together is that we will put together a plan that works for you. And that will help you to get to your individualized goals, whatever those are for yourself.

So it’s really about you becoming the best possible version of yourself, the healthiest version of yourself, the most badass version of yourself and making it last. This is about long term, sustainable results, not about quick fixes, okay.

So if you’re ready to lose weight, get stronger, run faster, run longer, then you’re ready for the Running Lean coaching project. Just go to runningleancoaching.com/apply. You’ll fill out a short application, you and I will jump on a quick zoom call. We’ll talk about your goals. We’ll see if this is a good fit for you. I would love to have you join me in the Running Lean coaching project. Just go to runningleancoaching.com/apply. Put in your application and we’ll see you soon. All right on to the topic.

So what is metabolic flexibility? At its simplest, metabolic flexibility is your body’s ability to use whatever fuel is available to it at the time. It means that your body’s metabolism is flexible, the ability of your body to metabolize different substrates, meaning different types of fuel. So different types of fuel could be food that you just ate could be used as fuel. It could be fuel that is stored in your muscles like glycogen.

It could be fuel that is stored in your fat stores could be stored body fat that you use as fuel. And so for most people, and I’ll get into this in just a minute for most people, though, they are only using like one source of fuel, mostly that stored glycogen, okay? And we want to change that we want to be able to tap into multiple sources of fuel, the two main sources of fuel we’re going to be talking about.

And the two main sort of preferred fuel sources that your body prefers to use, especially for exercise, like running, are going to be carbohydrates stored in your body. So sugar is stored in your body as glycogen in your muscles, and fat that’s stored in your body’s fat cells. Okay, so these are the two preferred fuel sources that we love to use it we’re very well adapted at using.

So the science calls this glucose oxidation and fat oxidation, okay. And something you have to understand about, you know, fat burning or a sugar burning is that we are always burning both at the same time. So it’s never just one or the other. Or very, you’re always burning a little bit of one or the other, okay? But what we’re talking about here is, is maximizing the amount of fat or, or glycogen that you’re burning, okay, so it’s never an all or nothing when it comes to fat and glucose oxidation, you’re always burning both.

But for example, the longer you’re out there running, the more fat that you’re actually burning, your body will, you know, if you’re running at a lower intensity, you will start out burning more carbohydrate, but that fat oxidation will continue to go up. And so what’s nice about you know, being really well fat adapted, is that you can burn much more fat much more efficiently.

And you can run for longer and longer distances without having to, you know, refuel, because you’ve got plenty of fuel on board at all times. And if you are a fat adapted athlete, so if you’re a low carb athlete, and you’ve become fat adapted, then you can even run at higher intensities, and still be very efficient at using fat as your main source of fuel. This is one of the reasons why we get into fat adaptation.

It’s because we want to be able to burn fat very, very effectively for long distance running. But also we can get into some pretty intense running as well. So they did a study a while back, it’s called the faster study and you can look it up. And one of the things they did was that they found that for the most part, most athletes that are, you know, the carb adapted athletes, so just your standard athletes, not fat adapted athletes, that once they get over 65% of VO2 Max, that they they tend to stop burning fat and start burning, mostly carbohydrate. Okay. So this is the majority of people out there.

Once you get over 65% VO2 max, you’re burning mostly carbohydrates up to 65%. And you’re burning mostly fat. And this goes across the board for most people. With the faster study, they found that the fat adapted athletes could burn much more fat than the carb adapted athletes. So their peak fat oxidation was 2.3 times higher in the fat adapted group.

So over twice as much fat they were able to burn. And they found that they could increase their intensity and still be burning mostly fat so they could get up to 76% of their VO2 max and still be burning more fat than carbohydrate and really didn’t need the carbohydrates in order to the carbohydrates in the form of fuel in order to achieve those kinds of numbers.

So just understand that one thing I think people get into this idea of becoming fat adapted, and they think that they’re just burning fat, you know, and that’s it. That’s the end of the story. Or if you’re not fat adapted, you’re only burning sugar, you’re only burning carbohydrates.

And really, it’s not the case, you’re always burning both, okay? Just understand that. But as a fat adapted athlete, you can take advantage of your levels of fat oxidation, which are going to be much higher than the standard of carb adapted athlete. And it’ll give you a bit of an edge.

So why am I even talking about this? Well, I’ve been really on this kick this whole month about talking about ancestral living, you know, and what we’ve done as human beings for millions of years. And really, for since like 2.5 million years ago, to about 10,000 years ago, humans have been very metabolically flexible, we’ve been able to, to burn fat very, very efficiently, we’re able to take advantage of other types of foods when they were available to us, you know, think about, you know, times when certain types of foods would have been scarce, we had to have different types of fuel, and we had to be able to metabolize those different types of fuel.

So for example, when we would hunt and you know, eat meat, or we are eating things like fish and eggs, very dense, nutrient dense types of foods, we could eat, we could hunt and eat a lot of meat, you know, and share that with the group. And then we might go for days without food. So in that case, we are consuming fuel in the form of, you know, meat and animal protein. But then we would go days, without food, where we would be basically using our own stored body fat as fuel, right?

This is the way we are designed to operate as human beings. We are very efficient fat burning machines, we always have been. What has happened in the last 50-60 years is that we’ve gotten away from that? And we’ve gotten more into just relying on very quick sources of energy, like carbohydrate, like sugar, like grains, like really concentrated refined carbohydrates, refined grains, that kind of stuff.

And the problem with that approach is that we really well, there’s all kinds of problems with that approach. But from an athletic standpoint, we’re only using one source of fuel when we do that, we’re not able to take advantage of the fact that we are really efficient fat burning machines. Okay, so back in the day humans would eat sporadically, we would take advantage of the fact that we could find things like tubers and nuts and seeds and fruit and things like that. And we would be able to use those things as fuel as well.

So we became really good, really efficient at being metabolically flexible. It’s one of the reasons we’ve survived. Whereas a lot of other hominid type species did not, you know, because we were able to have that flexibility. Okay. And all I’m proposing here is that we get that back. That’s it. That’s all I’m saying.

And especially if you’re a runner, then you are absolutely leaving a lot on the table. If you’re not taking advantage of metabolic flexibility, you absolutely are leaving a lot on the table. Our bodies are well adapted to feast and famine. Our bodies are well adapted to a variety of fuel sources, especially using stored body fat as a fuel source. Most people do not do that. Most people, most people are good at storing fat, but not actually using it as a source of fuel.

But we humans, we are really good at burning fat. We’ve been doing it for millions of years, I just want us to get back to being really efficient at burning fat, okay. And as a runner, you absolutely want to be taking advantage of this virtually unlimited source of fuel that you have on your body. stored body fat is an amazing source of fuel. And I talk to runners every single day and I coach runners on how to become fat adapted every single day.

And I get a lot of skeptical runners out there. They’re like I just don’t see how this is possible. I don’t see how, you know, not taking in all these gels and stuff and sports drinks that I’ve been doing forever. I don’t see how I can possibly run without all that stuff. And then they do it. And then they’re pretty surprised at how amazing they feel, okay?

But it’s not about just doing just using that one source of fuel. This is the thing I want to kind of drill home here today is that metabolic flexibility means you can use multiple fuel sources. So yes, that does mean that you can use carbohydrates as a fuel source as well as fat. But most runners don’t take advantage of the fat side of things. They’re only interested in the carbohydrate side of things.

But why would you leave a tool on the table, so to speak, you know, why not become fat adapted and get really, really good at burning fat? And also, you can use carbohydrates strategically, in order to have that flexibility for different types of activities, different intensities of running different distances, all right.

The problem is that most people are just metabolically inflexible. So most people, especially here in the United States are eating the standard American diet. It’s interesting that the acronym for that is SAD because it’s a sad diet. It’s so sad, it’s making us sad, it’s making us unhealthy, or it’s creating a nation of sick, weak, unhealthy, overweight people.

And one of the issues with this is that it’s a very, very high carbohydrate diet. And it means that you have to rely on just one fuel source for energy. So if you’re a runner, and you’re eating the standard American diet, you are relying on one source of fuel carbohydrates for energy for running, and you’re not taking advantage of being fat adapted.

So that standard American diet with all the carbs, you might be eating six, seven times a day, you know, you are relying on one source of fuel and you need it, you need it every couple of hours, or else you’re going to crash and burn.

Not to mention you’ve got to carb load before running the night before you got to carb load before you get out there and run you got to carb up during runs. You’ve got to carb up after runs or else you’re going to crash and burn. And this might work okay for you for running like it might help to fuel your runs. And you might be okay with that.

But eating that much carbohydrate, especially eating every few hours, it does a few things. Not good things by the way. For example, It ramps up your cravings for more carbs. So you just want more and more and more of that same stuff, same sugary goodness, you know, it causes your body to keep storing a lot of that excess energy as fat in your fat cells.

And because you’re not fat adapted, you can’t really tap into that fat for energy. So you just keep storing more and more fat in those fat cells. It causes massive spikes and dips in your blood sugar, and therefore your energy levels throughout the day.

And you end up being hungry all the time you feel fatigued, you have these massive cravings for more sugary foods, more carbohydrates, you get what people call hangry because you’re hungry and angry at the same time. And really, it just causes a host of issues not just weight gain, but it can lead to things like insulin resistance, which means your body is producing so much insulin that your body has become accustomed to that much insulin and so it’s no longer bringing your blood sugar down the way it’s supposed to.

Which means your body just keeps storing more and more fat in your fat cells. And insulin resistance is something that causes type two diabetes, and it leads to gaining a lot of weight and obesity and things like that.

And not to mention that eating that standard American diet with all the carbs and you know, eating just a ton of carbs, especially for running means you’re going to be hitting the wall at some point during a long run because you’re going to crash and burn unless you keep the sugar intake coming in.

But even that can have all kinds of digestive issues, it can cause digestive stress, and a lot of people cannot handle that much sugar while they’re out there running. And so they end up just sort of like either having to find a portapotty or they end up just crashing and burning. And you’re hitting the wall.

So that’s kind of the problem with the way that most people do this thing, right? They’re not metabolically flexible. So they have to rely on one source of fuel only for running. And you end up running out of fuel, you end up with insulin resistance with weight gain, and with a host of other metabolic issues, right. So that is the way that most people do it.

And I’m just saying here, listen, there’s another approach that you can take and you can become more metabolically flexible, you can actually train your body to use fat and carbohydrate as your two main fuel sources. very effectively, you can do this very effectively. So here are some of the benefits of metabolic flexibility.

So first of all, you can tap into different fuels and use different fuels for different types of activities, more intense activities, you can increase your carbohydrate intake, you can use different types of carbohydrates, you can use, you know, very concentrated forms of carbohydrates. So you can use slow burning types of carbohydrates. And you can use carbs for long distance activities, or for higher intensity activities. But one of the benefits is that you have this flexibility, and you have the ability to use different fuels.

So as you get into that higher, you know, intensity exercise closer to 65-70-80% of your VO2 max, when your fat oxidation starts to go down, you can actually increase your carbohydrate intake. And in preparation for that, you’ve got to do it ahead of time. But you can increase your carbohydrate intake, and maintain high intensity levels, without as much carb intake as you would need if you were not fat adapted.

Okay, so that’s one amazing benefit, obviously, you’re gonna burn more fat. One of the biggest benefits here is that you burn fat very efficiently. And when you burn fat, you know you’re losing weight, it’s much easier to lose weight. If you become fat adapted, if you actually train your body to be a really efficient fat burning machine, right. And you use fat as a source of fuel for running, then you’re going to lose weight much easier, and you’re no longer going to be storing so much body fat, you’ll be burning that body fat. Okay, so losing weight becomes much much easier when you’re fat adapted.

You know, one of the other benefits is that you can improve your athletic performance not only running longer, but running faster again, because you can tap into different types of fuel, you’re not relying on just fat, or just carbohydrate as a fuel source.

One of the other things is that you become more insulin sensitive. So instead of becoming insulin resistant, your body becomes more sensitive to the effects of insulin, meaning your blood sugar’s will normalize, you won’t have those spikes, and crashes and blood sugars, you’re going to have more all day energy. So you’re going to have more steady energy throughout the day, which is amazing.

You’re going to be able to think more clearly because your brain uses fat as a source of fuel. So your cognitive function will be improved. You will sleep better at night, you will feel more rested when you wake up in the morning. And going forward with your weight management or weight maintenance. That becomes much much easier if you are metabolically flexible. It’s much harder if you’re relying on just carbohydrate as a fuel source, because it just it makes managing your weight much more of a challenge because then you have all these other things the insulin resistance and the weight, you know the storing body, storing of more body fat, and incessant weight gain and hunger levels and things like that.

So being metabolically flexible means that you have the ability to tap into multiple sources of fuel, and you have the ability to improve your athletic performance and just become this amazing fat burning machine as well as having the ability to use carbohydrates as fuel.

One thing a lot of people one mistake a lot of people make when they become fat adapted is they don’t regularly use carbohydrates as a fuel source for certain athletic endeavors. And you got to kind of train yourself to use carbs as well as you know, your stored body fat as fuel, you don’t want to just become fat adapted and wait six months, and then, you know, try carbs for a race, because your body at that point is so used to using fat as fuel. It’s not really used to having that carbohydrate glycogen stored as fuel the way that it used to when you were carb adapted.

So you have to actually train yourself to become more carb adapted as you get into some of the more intense running and things like that. So that’s just something to keep in mind. So how do you do this? How do you become more metabolically flexible?

There’s a couple things you can do to get started, number one, is getting fat adapted, this is really important. So you gotta get your body burning fat more efficiently. And most runners just don’t do this. Right. So you got to get off the sugar, you got to get off the refined grains and things like that, and start training your body. To use fat as a fuel source, one of the easiest ways you can do this is just train in the fasted state.

Don’t eat anything before you run, like let’s say you run in the morning, don’t eat anything after dinner the night before, you know, just get out there and start running in that fasted state. And that will force your body to start using stored body fat as fuel. And of course, you have to lay off the carbs too, that’s going to kind of hinder this process.

But getting fat adapted is one of the best things you can do to become more metabolically flexible, because now you’ve taken advantage of this fuel source that most runners are not using. Okay. The other thing you can do to become more metabolically flexible, is to exercise regularly. And you gotta do it the right way, you have to be doing both aerobic type exercises. So long distance running would fall into that category beautifully, right.

But also you have to include some form of high intensity exercising, so something like weightlifting or HIIT training, or sprinting, all those things are going to help increase that intensity that you’re putting on your, your systems, you know, your muscles, your aerobic system, you’re, you’re gonna help to increase your lactate threshold and things like that. All those things will help you to become more efficient at burning fat and help you to become more metabolically flexible. Okay.

So getting fat adapted, and then doing both aerobic type of exercise and higher intensity, shorter duration, but higher intensity exercises, is going to kind of kick things into gear for you there. Okay? So think about this this week, I want you to think about becoming more metabolically flexible. There’s so many reasons why you want to do this. You don’t want to be doing things the way that most people are doing things. Because the way most people are doing things does not work. It does not work for the majority of us, okay?

And if you’re one of those people, and you find yourself wanting to lose some weight, and you find yourself wanting to improve your running performance, and you find yourself not wanting to rely on all the carbs and having all the negative things that go along with that thing, consider becoming fat adapted, and taking advantage of that metabolic flexibility that we as humans have developed over millions of years. Let’s just get back to that. Cool. All right, that’s all I got for you this week. Love you all, keep on Running Lean, and I will talk to you soon.

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