In this insightful episode, hosts Paul Warloski, Dr. Paul Laursen, and Marjaana Rakai break down the crucial topic of insulin sensitivity and resistance—a metabolic issue that affects not just people with diabetes but endurance athletes too. They explore how insulin works in the body, how chronic exposure to sugar can lead to insulin resistance, and why even fit athletes can suffer from poor metabolic health. Drawing from personal experience, science, and practical tips, they discuss how dietary choices, strength training, stress, and lifestyle all shape our insulin response. Importantly, they offer actionable advice for athletes who want to optimize performance, avoid midsection weight gain, and stay metabolically healthy as they age.

Key Takeaways

• Insulin is essential for moving glucose into muscle and fat cells but becomes problematic when chronically elevated.
• Advanced Glycation End Products (AGEs) from persistent high glucose contribute to aging and health decline.
• You can't outrun a bad diet—even fit athletes can become metabolically unhealthy with excessive sugar intake.
• Insulin sensitivity declines with age, high stress, or sugar-heavy diets, but can be reversed.
• Strength training and endurance training increase insulin sensitivity by increasing muscle mass and GLUT4 activity.
• Common signs of insulin resistance: stubborn fat, reduced performance, fatigue, poor sleep, and high blood pressure.
• Fasted training and reducing sugar can restore insulin sensitivity and boost fat metabolism.
• Lifestyle plays a huge role: stress and processed foods drive insulin resistance, especially in aging athletes.

• Paul Warloski - Endurance, Strength Training, Yoga
• Marjaana Rakai - Tired Mom Runs - Where fitness meets motherhood.

So if you want to look young, You don't want to be, you don't want to have high insulin all the time. If you have high insulin all the time, means you have high glucose all the time, means you got these advanced glycation end products in your body all the time.

Hello and welcome to the Athletes Compass podcast where we navigate training, fitness and health for everyday athletes. We're going to get just a little nerdy today in talking about nutrition because today we're diving into a topic that affects not only our performance as endurance athletes, but also our health, insulin sensitivity and insulin resistance. Insulin plays a key role in how our bodies use and store energy and whether we respond to it well.

or not so well can shape everything from long-term health risks to how we fuel and recover from training. We'll unpack what these terms mean, why they matter for everyday athletes, and how we can tell if we're moving in the right direction. So Paul, can you start by explaining in simple terms what insulin does in the body and why it's essential for athletes and non-athletes?

Yeah. Yeah. So insulin is your, well, they say it's one of the key hormones, like it's just a keystone kind of hormone in the body. And it's, it's really, you know, controlling and dictating metabolism. It's produced in your pancreas. And specifically in the islets of Langerhans , they say. Then basically it's pushing out the, in the pancreas, it's pushing out insulin into the bloodstream.

And it's helping move your sugar, your glucose, into the cells of the body. It's basically telling whether to go into the cells or come out of the cells. And specifically the cells it's going into is like glycogen, muscle, and some fat as well. So that's the key thing. So basically you eat your food and then

inevitably there's usually some glucose in that food and right around the, bloodstream, the islets are pushing in insulin at a level that's proportionate to the amount of glucose that it sees, that it appears. So very sensitive in terms of its regulation. And yeah, that's...

That's what it does. And if you don't, like we know we have type one diabetics that they can't produce insulin. when they, like it's life threatening if they can't produce that insulin because then they're left with all of this spillout of glucose and glucose is, it's ultimately a toxin. So without, if it just kind of hangs around and doesn't go into

the cells, it winds up forming substances in the body that are ultimately

it's ⁓ advanced glycation end product, abbreviated AGEs So if you have a lot of glucose in your system all the time, it basically, causes, this glycated, protein to form.

you're made of protein and basically you, wind up developing, aging elements in your body. you're, you're, you know, your skin doesn't stretch like it used to, which happens in all of us as we age. But this process of high glycemia speeds that, which, you know, we're all vain individuals, right? We've all got egos. You, you kind of want to keep that.

⁓ at bay as long as you can, right? So if you want to look young, you don't want to have high insulin all the time. If you have high insulin all the time, means you have high glucose all the time, means you got these advanced glycation end products in your body all the time.

That's super interesting and depressing.

now I'm flicking my skin, seeing what happens here.

Well, well, not depressing for me too, because I reflect on my own, you know, really, I got the info wrong. When I was, taking sports science in university and I was being told that I can have as much sugar as I wanted in my diet because it was good for my muscle glycogen levels. And that was what was key for me to perform.

I was like, I was all in. It's like, two liters of Coke a day. No problem. It's terrible. Terrible, right? So imagine all the, advanced glycation end product work I was doing there at that point. Not good. So fortunately I the, saw the light in time and did some reversing. And if you're listening, you can do that too.

You're still looking pretty young.

Cheers. But again, I don't think I, I show you some photos, MJ. I wasn't. So I was, I was aging. I had a good, a good little tummy on me and everything. It was pretty, it's, it's remarkable. I know, but we're, we're all like that. We're, we're all so remember that every cell in your body gets turned over every six months. So you are what you eat and

What?

That's hard to believe.

Yeah.

You can do that too. So if you want to be a certain way in six months from now, you can, you just have to change the food. will be a byproduct of the food that you consume in the next six months. So think about that, the listener. you, that's whatever in your, you're having for dinner, those nutrients, those micro, macros, polyphenols.

everything will go in towards making you who you are in the next bit. So what do you want to be? think about that when you're going down the grocery aisle.

basically, if you don't have enough insulin to open up those ports into the muscle cells or cells, end up all that glucose just in your bloodstream and you get high blood sugar.

Yeah, which you don't want, right? So you want to have good control of your blood sugar levels. Yeah. And I think you know this, we all have these different periods of hyper and hypoglycemia, right? And hypoglycemia means you've got low blood sugar. And that's a problem because you definitely feel really low in energy. Mum sometimes feels hangry.

Yeah.

And if she's hypoglycemic, right? So these are, yeah, these are, that's a low, but hyperglycemia is a lot harder to perceive, but you, it's still, it's still there. A lot of times people feel anxious when they're hyperglycemic.

So the more glucose comes into the system, the more insulin is released?

Yeah, in a healthy working pancreas islets combo, then that's, yeah, then that's, it's one-on-one, which is why you can use those things like CGMs, constant blood glucose meters, to, as a surrogate of how much insulin's being produced, likely, right? Like it's not, you're not measuring insulin, but we, you know, if all of a sudden you go and have a,

Okay.

a Dairy Queen Blizzard. I know that's one of the biggest ones. My buddy wears a CGM often and he says, yeah, when he went to with his daughter to get a Dairy Queen Blizzard, holy cow, he just had, his blood glucose in milligrams per deciliter was up to 200, I think, which is huge, massive surge. think typical normal is sitting around 90. So yeah, it was just off the charts with that. So yeah, that's...

his insulin level would likely be high as well. And I think, you know, the key thing that you want to consider is that when insulin is really high, it's not just the driver for storing blood glucose, it's also going to be the big driver for storing fat. And so it puts it puts everything into storage. And it's ultimately the problem, one of the key problems for

modern day society in terms of over fat. We had Phil Maffetone on the podcast, he talks about over fat, right? So it creates that. It creates that central adiposity development and drive for storing more fat.

So a few times I've come to this question from athletes who are training for marathon or training for something long distance and they keep putting on weight. Is this related to eating a lot of carbohydrates on their longer runs, longer rides and maybe getting a little

too much glucose in their bloodstream that is not being used muscles. And then it turns out, too much excess energy and it gets stored as fat. And they're complaining, why am I, I'm training so hard. Why am I just gaining weight?

Yeah, that's it. So ultimately we now know that you can't outrun a bad diet. So it wasn't always... And again, we talked about our young upbringing. You don't see this as much. You don't see the hidden fat that's in the back of very fit athletes, young athletes. But, and again, I only know this from my own experience. So I got to about 35 and I was still having the

high carbohydrate diet maybe not too high carbohydrate, but too much sugar in my diet ultimately, right? And then I had the same sort of problem where I was just carrying a lot more excess body fat around and I couldn't, could no longer get lean ultimately. So that's the problem is just, think sugar is the key one, right? So we don't want to villainize carbohydrates.

There's healthy carbohydrates, of course, so many, know, fruits and vegetables, and that's all carbohydrates. But it's like if your sugar level is high, and then if your quantity of processed food usually comes with unhelpful, carbohydrates at the same time. And these are always, these tend to be spiking your blood glucose level and then spiking your insulin level.

and leading to the problem that you just described, MJ.

So let's talk about the difference between being insulin sensitive and resistant on a cellular level. What does that mean?

Yep. So if you're insulin sensitive, are basically the, as that insulin molecule passes by your cell, it fits like a key into a lock and it opens up the lock and the door and then the glucose goes into the cell. that's being insulin sensitive. That's normal.

natural, that's the young phenotype. In the older phenotype, it's seen insulin all its life. It's had these issues and stuff. You start to develop insulin resistance. In other words,

I guess it's just like, can be anything in the body or you become resistant to it, but it's like, it's kind of bored of the old insulin. We have high levels of it all the time, all around here, and it gets tired of, and it doesn't really know what to do with all that insulin. And it just becomes a little bit more sluggish and it doesn't respond as it used to. And as a result, that insulin just doesn't work as well and sugar levels stay high and insulin...

doesn't have the same sort of effect. And this relates to what we call metabolic flexibility. So your ability to process carbohydrates appropriately. I think that's it.

Is there a way to know that you're getting a little tired of that same old insulin or without any tests?

Well, I think it relates to what you just said before, MJ. It relates to that fat isn't going away like it used to when I used to train the house down, for whatever reason that's still hanging around. So that's a key signal that something might be off and you're becoming less sensitive, more resistant.

Is there any

Are there other early warning signs of insulin resistance besides the fat not going away?

It's really around the adiposity. The performance goes down as well too. So you're not as able to... We talked about in the last podcast, the adaptation energy. So you're not as easy to adapt to the training. So you don't feel like your build phase isn't going to be as effective anymore because you're just not... Now you're not like the...

the fat metabolism as the base is what drives the adaptation. So if you're getting over training more, like a lot of fatigue, that's what Phil Maftone and I have coined before the unhealthy athlete, right? Athletes look fit and healthy, but in...

in lot of contexts, they're just, they're not. There's an underlying like base level of chronic fatigue that sits within that athlete. So, and this is, it usually spills over as a metabolic issue with the, certainly with the problems around the adiposity because you're no longer able to take the fat out of the adipose stores.

and you've only got the one way driver into the fat. And that comes with all these cascade of other issues as well, including like something called reactive oxygen species, free radicals, like a poor immune system that just doesn't work to clean things up anymore in you, and usually poor sleep. So any of these sort of symptoms,

relate to this insulin resistance.

Paul, is this an age thing? Do older people, you know, does it become more of a problem as we get older or is it simply too much sugar on a constant basis or both? Okay.

Yeah, it's kind of both Paul. Yeah, because

again, I think it's, we arrive on the planet, you know, and then we get exposure to sugar and insulin throughout our life, right? And then the more, so the longer we're exposed to that from an age standpoint or the intensity of that exposure, right? If in the case where,

your main lining sugar all the time, like I used to do. Honestly, like I was addicted to Coca-Cola or Pepsi during university. And I actually thought that I could, because of all the training that I was doing, I could totally get away with that. And it would just be totally fine. Like I had my facts wrong. so yeah, so I had a high intensity ultimately of glucose on my cells a long time. And it was, yeah, it took me a while to...

to figure out that I couldn't outrun the high sugar diet. So either or, so again, also with age as well and time, you're gonna have a harder time kind of processing these as well. But it's all correctable. That's the cool thing that I discovered is that I could pull that out, totally swap my diet and become insulin sensitive again, even though I was insulin resistant.

⁓ the ⁓ other thing that happens too is high blood pressure. So I also had high blood pressure. So I actually went with anxiety to the doctor. I was working at High Performance Sport New Zealand with the Olympic program there. And the combo of the stressful job leading the program in physiology alongside of the high sugar diet. I went, yeah, I actually had to go and get things tested out. I couldn't believe my blood pressure was...

like 135 over, 81, 82. So I had mild hypertension and this was a, I was like a 38 year old, worker. Um, you know, you'd, that's a pretty young worker. You'd sort of think with the central adiposity just starting to kind of develop and, but yeah, that was the high blood pressure kind of came in there as well. Swapped the diet, same sort of time around Tim Noakes was doing that. And it was really quick. The adaptation for me after swapping the diet.

And getting rid of the sugar, that was the main thing, just taking the sugar out and then just going to a more of a whole food kind of diet. But certainly lower on the carbohydrate side, that worked for me. And I've sort of never looked back. It's always what I love. I love consuming now. It works so much better for me. yeah, I'm pretty lean individual and still fighting fit. So yeah, it can be completely reversed.

Why should everyday endurance athletes care about whether they're insulin sensitive or resistant, even if they aren't diabetic? And you've kind of answered this already, but I want to kind of drill down a little bit further. Why do we care?

Yeah, I think it just goes to your, it goes to your health at the end of the day. And even if you're an athlete, you might still be jeopardizing your health if you're kind of sabotaging that training and having, having sugar all the time. It's like, it's remarkable. so, you know, I'm working with, Luke Evans who won the, ⁓ won the Ironman Canada, right? On with Athletica and you know, he was really.

of the belief, you can listen to that podcast that he had to have sugar that sort of fueling all of the sessions. And a lot of people have that same belief. And then it takes a little bit of experimentation and sometimes some coaching to realize that you don't. And yeah, you really don't know what you're missing until you actually

remove it, guess, and remove that practice and realize that you don't really have to do things that way necessarily. But it's not easy.

⁓

It's also a little bit of an emotional issue and we get a little bit pushed back about talking about low carb and not taking 90 grams of sugar on people's rides or runs.

like if you're someone who is gaining weight when you're training, you can kind of like, even if you don't believe in, because belief comes into picture, right? It's our nutrition. We're all experts what we eat and how our body works. But if you're somebody who is gaining weight when you really shouldn't, because you're working hard, training hard, and you're aging, like you can kind of have a

I think about, do you really need to fuel with gels or sugar or can you switch to natural carbohydrates or even just like reduce the carbohydrate intake that you do take on your high intensity sessions? You know, also lifestyle factors, like when we get kids, our

Our activity level drops if you're not careful. You got to take the lifestyle activity into account, your training into account and what you put in your mouth and then kind of get a picture of why are you gaining weight if you're somebody who's gaining weight, right?

Yeah, for sure. And again, huge empathy to the parents out there. And again, I'm a parent as well. So I know that kids will gravitate towards carbohydrates and sugar type foods. So they're around your house often, and they just find their ways around, right? And then there are foods on the table. It's easy just to kind of grab that.

So it's really, I've spoken to so many Athletica users or otherwise that want to kind of give this a go, but it doesn't fit with the lifestyle and especially kids at the same time. empathy there, it's not an easy one. It might have to be a work on project and it have to be a little bit of a willpower one. I don't have the answer for every individual context that's out there. You've got to sort of figure that out yourself.

These are the principles. These are things you should watch out for. yeah, again, and the more you can sort of switch towards a whole food alternative and stay away from the treaty little snack things that, you know, and process package stuff, the better you're gonna be off, that's for sure.

Mm-hmm.

How does exercise, especially endurance training and strength training, affect insulin sensitivity?

Yeah, helps it. So the bigger, like the big sink that you've got to absorb your carbohydrate amount comes from the skeletal muscle, right? So, and then the second is the liver, but you, you you don't want to, you really want to build that sink as big as you can make it. So the more you both endurance training and strength train, the more you, you know, you make a larger bed.

that way.

or sink that you can take in that glucose. Tim Noakes actually feels that's the key role of the skeletal muscle now as he's continuing to go down this path. It's job there is to store that carbohydrate for us. Because again, as mentioned, it's a little bit of a toxic substance as well. Whilst vital for the brain.

in terms of at least getting a certain amount in there, it is in too much, too high levels. Not a good thing. Remember that the liver's job is to, it's like the orchestra leader, right? Like it's the conductor of the orchestra and the liver is kind of pushing out the amount of carbohydrate, glucose and fat and ketones just to the right amount that it can. So you've just, ⁓ yeah, you've got to, ⁓

Sorry, back to your question, Paul. You're talking about what role does the exercise play. Well, yeah, it's really, really good for it because

back to the key and lock analogy, the insulin was moving up a, basically an opening called GLUT4 And what exercise does, when you move your muscle,

Calcium is used in the process of moving the muscle and calcium actually also is another trigger for an internal movement of the GLUT4 membrane to the membrane. So it's another means of actually opening up the sink to bring glucose in. So this is why, you know, anyone, anyone ultimately, and even in my context as a young athlete, because I was training in the house now all the time,

I did get, you get away with it for a long, long time because you're always exercising. So then the GLUT4 four is always kind of open in the cells and therefore, you know, there are a lot of glucose is going straight into the cells and you're maintaining with a load of exercise. You're maintaining at least a certain, a certain level of, of, ⁓ of glycemia where it's not too hyperglycemia. but again, over time, you usually can't keep that same level up. So yeah.

To your question, Paul, it's instrumental. It makes a big difference on both ends, both the strength and the endurance training through the GLUT4 , independent production.

And that's why it's really, really good to go for a little walk after you eat supper. And that's where like small kid parents, they struggle because you like you eat supper and then it's bath time and bedtime. You know, it just comes creeping in, but the strength training, want to double tap on that. Like imagine if you're, if you can grow your sink bigger, you can kind of, you know, improve your situation. But what really happens with

Mm.

Yes.

age and kids and all the lower activity in our everyday life is that we also lose muscle mass. So , our sink it's smaller. So that's why I am so dedicated to keep my muscle mass up as long as I can. And that's what our parents used to do. They owned farms and they worked in the farms and they had muscle mass longer than we do. Our generation is doomed.

Mm-hmm. Yeah.

Not necessarily doomed, you just have to have awareness of this and you need to emphasize these important behaviors like you're just kind of mentioning, like going for the walk after dinner, strength training, doing everything you can to hold on to that muscle mass. ⁓ And recognizing that all these mechanisms are sort of sitting around there.

Mm-hmm.

Mm-hmm.

From the endurance athlete perspective, like we often skip, the first session to skip is strength training. If you think about insulin sensitivity, again, if you're somebody who is training a lot and then gaining weight, that would be the last session I would skip, the strength session.

.

Hmm.

Yeah. ⁓

Just because

I wanna keep the sink as big as possible.

Yeah,

yeah, I agree.

Along that line of thinking, so if somebody learns or suspects that they might be insulin resistant, what are some of the steps they should take in training diet, lifestyle, what should they be changing?

Well, I think it's...

What would be your

first top five things, you know?

⁓ would ⁓ scan your diet and ask yourself, I ingesting sugar maybe too much in my diet? Really look at the ingredients that you're having. then second, because again, remember that the master conductor is the insulin, right? Like that's the key regulatory hormone. That's not debated. So that's the key one you want to look at. And the only way...

really you can up your insulin level is through the diet. Stress plays as well because stress causes for cortisol release, which is a glucocorticoid. basically it causes for a breakdown of, causes your liver to push out more glucose and then you get more insulin. either way, stress and...

stress and sugar are the two biggest culprits. And usually when you're stressed, what do you feel like? Usually craving a sweet, right? So it's a vicious sort of circle and cycle, but I would do that analysis first. And then, yeah, I would go back to the Mikki Williden podcast that we did and really look at, you know, what are some ways that we can potentially curb and change? And she was recommending

you know, if you want to stay away from the carb fat debate, no problem, but up your protein level. And, ⁓ you know, that's usually a really good way to make a big change and, you know, create satiation. you're, you're, yeah, you're satiated. You're not hungry. That's the key. The key problem, right? Is that your body is often hungry. And if you're hungry, you should, you should be eating. that's the apistat that's telling you something that you're missing.

usually at the micronutrient deficit. And a lot of times with the protein source, you're getting a lot of the micronutrients that are kind of coming in there and you curb the satiety signal. And that just calms and helps things so much. Exercise is another one, Like the tube or exercise also usually creates a ⁓ reduction in the hunger too, because it naturally does that through the ketones and fat that...

that's usually put out there when you exercise. So I think those would be my top ones, Paul, is like, yeah, sugar check, stress check, protein level check, ⁓ exercise check. I probably got four. Maybe MJ, you got a fifth in there for me? nice one.

Strength training. Of course.

There we go.

Paul, I want to double that what you said there, decreases your appetite. It's not always. I remember when I was.

only

meant in the acute phase. So yeah.

Yeah, like I remember doing long rides in the Dubai desert there and I was constantly hungry and I would like every 20 minutes I would eat something because I was just hungry all the time. But I was doing things a little differently back then.

Hmm.

Yeah, you were having a lot of gels, right, and these things?

⁓ yeah, chocolate bars, candy, grapes, anything that I could have, would eat. Coke.

Yeah, so

for sure. mean, it's like your small glucose pool, right? It's just like, it's so small and it's kind of battling. And it's just, you don't have the fat levels, the base to be able to handle the exercise there. So yeah, like that's almost like you're bonking all the time we say, right? Paul would know that in the cycling context.

Mm-hmm.

Mm-hmm.

Yeah.

So it's like, and again, if you're bonking all the time, you're probably deficient in your lower level base and your ability to burn fat. So if you're going to do a metabolic test, right, your crossover point, and that's when we're looking on the test and we're looking at how much fat you're burning and carbohydrate you're burning progressively up the higher levels you go, you have a really early crossover point and you're going almost straight to carbohydrates as, you know, after you hit like

40 % of VO2 max, which is really low. And you should be up towards 60 or 70 % ideally before you're crossing over where there's, and when we say crossover, we're talking about an equal proportion of fat and carbohydrate that's being burnt in the test. ⁓ So on a standard metabolic test.

Right.

Mm-hmm. Mm-hmm.

So I definitely wasn't able to tap into my fat stores then back then, but would you then recommend starting experimenting with fastened training to improve that?

Yeah, definitely. And again, we just touched on it in the last podcast. We spoke about the periodizing your nutrition. So yeah, that's a great place to kind of start. Now, if you're listening to this and you're freaking out about even contemplating ⁓ a fasted training session in the morning, probably tells you that you might benefit from that actually. it's... Yeah, and how do you do it? So how do you do your fasted sessions, MJ? What do you do?

Hmm.

⁓

I get my coffee, so a little bit of a wakey-wakey and then I head out.

Yeah.

Yeah, exactly. I'm 100 % the same. So it's like, yeah, I know I've got a ride planned with either myself or a buddy. And it's like, set the alarm, coffee first, use the toilet, out the door. And you're just prolonging the fast, right? And then when you finish the workout, you should feel pretty good in that workout too. And then, yeah, and of course my coffee's black.

MJ's might, she might have ⁓ a bulletproof or whatever she has, but it's like, yeah, it's, it's like, it's sort of a lower carb sort of thing. And then yeah, a big breakfast when you get home and just even changing that instead of having breakfast before versus after it's like you're prolonging the fasted period of time. Like that's the window where you've been under low insulin level from, from the, from your morning, right? Again,

you

Yeah.

Like you, whenever you have your dinner, whenever that is in your life, maybe it's six or seven o'clock at night, whatever it might be, like you're not eating past that time. And then you're fasting right through the night and then prolonging that fast. you're moving over to say, you're not going to eat till nine or 10. You've almost had like a 14 hour window or more.

where you're not eating and that's like a period of time when insulin is low and when insulin is low in your body, it's signaling for you to replace the fuel that you used to use with not with glucose but with fat. So you're increasing your fat metabolism by doing that method.

What about, this is not technically fasted, but what about like if you eat eggs or very like high protein, right? Same thing?

Yeah, a great,

the insulin response is really, the glucose response and the insulin response is pretty low to that. So that's a great alternate. And I should also add, like we mentioned about the continuous blood glucose monitors, but if you have any doubts about this, try to see if you can get your hands on one of those things, because they'll tell you, you'll learn so much from it. If you have the resources to be able to do it, you will learn a heap.

in terms of the foods that you respond to, in terms of those that are spiking your glucose and insulin, or the stress elements in your life that are causing that. And yeah, like you're an individual listening and you will find out so much about that whole process if you do that.

Thanks for listening today to the athletes compass podcast. Take a moment now subscribe, share, and let's keep navigating this endurance adventure together. Improve your training with the science based training platform, Athletica and join the conversation at the Athletica forum for Marjaana Rakai and Dr. Paul Laursen

I'm Paul Warloski and this has been the Athletes Compass Podcast. Thank you so much for listening.