Lots of runners look pretty healthy on the outside. They exercise a lot, maintain a decent weight, have low body fat percentage, low BMI, and generally look fit. But inside there could be a lot …
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 191 of Running Lean. My name is Patrick McGilvray, The Weight Loss Coach for Runners and today: Fit But Unhealthy. So, lots of runners look pretty healthy on the outside, they exercise a lot, they maintain a decent weight, they have a low body fat percentage, low BMI, they generally look and feel fit. but inside there could be a lot more going on that no one really sees.
So I came across this study recently that looked at low carbohydrate diets versus high carbohydrate diets and their effects on athletic performance. And the results are pretty interesting from the athletic performance standpoint, but also kind of surprising from a health perspective.
So today, I’m going to look at what it means to be fit but unhealthy, and what you can do to make sure you are both. But first, as The Weight Loss Coach for Runners, I’ve helped hundreds of runners over the last few years lose a lot of weight; but here’s a little secret to the people who I work with, it’s not about losing weight. I know it sounds contrary, but hear me out.
Losing weight is great. And it inevitably happens, but the real goal of working together is to help you become the healthiest and most badass version of yourself. When you make the commitment to change your relationship with food and exercise when you focus on building strength and endurance.
When you do the internal work of developing the right mindset, you will absolutely transform yourself into a leaner, stronger runner and the healthiest version of yourself yet. So weight loss is not the goal. It’s just a nice side effect of you becoming your fittest and healthiest self.
So make the commitment today to improve your health and fitness. And you’ll lose that extra weight along the way. And if you want a little help with all this, as always, you can join the Running Lean Coaching Project.
That’s my unique weight loss coaching program for runners. Just go to runningleancoaching.com/join to learn more about that. And if you want a little bit of help, just getting started with all this stuff, then I have just the thing to help you get started on the right track.
I put together a free training for you. It’s about an hour long, it’s called Five Simple Steps To Becoming A Leaner Stronger Runner. I will teach you how to lose weight the right way and keep it off for good without running a million miles a week.
A few of the things that you’re gonna learn in this in depth training, why running more and eating less is not an effective way to lose weight, the one thing runners typically don’t do when they are trying to lose weight, the best fuel to use to improve your endurance and help your weight loss, and the right mindset shifts required to make all these changes last for life.
You’re going to learn how to crush your weight loss goals and your running goals directly from me, The Weight Loss Coach for Runners. So if you’re ready to get leaner and stronger, to run faster and longer and to become the healthiest, most badass version of yourself, then you need to check out this free training now just go to runningleancoaching.com and click on Free Training. Cool. Awesome.
Okay, so let’s talk about Fit But Unhealthy. So I came across this study recently. The study was called low and high carbohydrate isocaloric diets on performance, fat oxidation, glucose and cardio metabolic health in middle age males. Kind of a mouthful.
This was published in the Journal Frontiers in nutrition in February of 2023. So it’s a pretty recent study. And the study was conducted by some of the pretty well known researchers in the low carb endurance and athletic world like Professor Tim Noakes, Dominic D’Agostino, Dr. Jeff Bullock.
And one of the reasons that they did this study is that since the 1970s, there has been this shift towards a high carbohydrate, low fat diet for health benefits, but also for training benefits. You know, a lot of the professional athletes since the 70s have shifted to a high carbohydrate, low fat diet because they want to reap the benefits of all the carbohydrates in their diet.
So that they can, you know, run faster, right and, and improve their athletic performance. Most athletes hit a crossover point in their fuel system. So they go from burning mostly fat to almost exclusively burning carbohydrates.
So they reach this crossover point where fat burning effectively shuts down around 85% of the of their VO2 max. So around 85% of most athletes’ VO2 max, they hit this crossover point where fat burning pretty much shuts down to zero.
And unless you have ample stores of carbohydrate to use this fuel, you bonk you crash and burn, you hit the wall. So countering all of this, this is what’s been known and been followed and adhered to, since the 1970s or so encountering all of this is the fact that there’s a lot of athletes and a huge growing number of athletes that have been following a low carb high fat diet.
And they have been able to dramatically increase their fuel crossover point to well above that 85% mark previously seen. So they wanted to do this study, to just see what was going on here and really, you know, try to predict or try to show what would happen between these two groups of athletes, the low carb diet athletes and the high carb diet athletes.
They wanted to see what the results would be on athletic performance. So they conducted this study, it was 31 days, so it was four weeks long. And they compare the two groups of competitive athletes, these were middle aged men in their 40s, they were in good shape, they had low body fat percentages, like 12-16% body fat, low BMI.
They exercised around six hours a week. And so they were competitive athletes in their 40s, mostly runners, and they divided them into two groups, they had one group that was a low carb high fat diet, the other group was a high carb low fat diet.
They assessed both diets, and they were strictly controlling macros calories and their training load. So this study was really well done. And they were very strict about making sure the only difference in these two groups of men was that their one group was eating a low carb, higher fat diet, and the other was eating a high carb lower fat diet.
And then they had them do some performance tests. So each of the subjects in the test visited the lab on 10 different occasions during that 31 day period. And they performed tests periodically, but the two main tests that they did was a one mile time trial, and then six by 800 sprints.
And so they did testing throughout, but they did some time trials at the beginning. And then at the end of the study. And all these things were very tightly controlled, all the variables were tightly controlled, to make sure the only difference between the groups was their dietary intervention.
Now, the performance side of things was pretty interesting because the results showed that both groups performed almost exactly the same in these high intensity exercises. So there was no difference really between the performance of the low carb group and the high carb group.
There was a huge difference though in fat burning. So the high carb, low fat group, their fat burning peaked around .69 grams of fat burn per minute. Whereas the low carb group, their fat burning peaked around 1.85 grams per minute, which is the highest rate of fat oxidation ever recorded.
Okay, so the big difference between these two groups was the amount of fat that the low carb group was able to burn and they were at 1.85 grams per minute where the high carb group peaked around .7 grams of fat burn per minute. That’s a huge, huge difference.
So what this is saying is that depending on your dietary protocol, either way, you’re going to be able to perform at high intensities, about the same whether you’re doing a low carb diet or a high carb diet, okay?
So we can sort of take this off the table that a high carb diet is required to perform at higher intensities. Okay. So something else that I found really interesting and this is what prompted me to want to talk about this today is that in the group that was eating the high carb diet, they were doing all these blood tests on on all these people just to see like, you know, what, they were just measuring all kinds of things.
And one of the things they were looking at was blood glucose averages, and they did like fasting blood glucose tests. And one thing that was really fascinating is that the high carb group, 30% of them had average blood glucose greater than 100 milligrams per deciliter, which is consistent with prediabetes. So 100-125 is diagnosed as pre diabetes.
And there’s where in the 111 to 115 range, on average, 30% of these super fit competitive athletes with low BMI 12 to 16%, body fat, they looked great. They were very competitive runners, they appeared on the outside to be super fit, but are they healthy?
They’re being diagnosed with pre diabetes, because of their blood sugar being greater than 100 milligrams per deciliter on average during this 31 day study. And they did these tests many, many times. So this wasn’t like a one time deal.
The other interesting thing about this is that these people were also the greatest responders to carbohydrate restriction, which means that those individuals with a higher mean glucose, so the higher the individuals with those prediabetes numbers with the higher mean glucose, were more responsive to carbohydrate restriction treatment.
And all of their glycemic parameters were greatly improved if they switch to a low carb high fat diet. So average glucose was significantly lower, starting on day eight of the low carb and then remained lower throughout. And so the 31 day average glucose levels were down by 15%.
If they had switched to that low carb high fat diet. So some of the key findings that I’m just going to read this to you, these are some key findings from the study itself. So one of them is that athletes achieved equivalent exercise performance during a one mile time trial and a six by 800 meter interval session after a 31 day habituation to low carb or high carb diets.
When controlling calories training load, body composition changes across the groups. Another key finding during the later stages of the six by 800 interval sessions athletes achieve the highest rates of fat oxidation yet reported. According to current understanding, this is paradoxical since these high rates were measured in subjects exercising edit intensity, which was a which the rate of fat oxidation should be approaching zero.
Okay, so these were, the intensity level was greater than 90% of their VO2 max and their fat oxidation should have been at zero, but it was increasing. Crazy, right? And the low carb high fat consistently reduced glucose levels and glucose variability, which along with a large inverse relationship observed between main glucose on high carb and the percentage change mean glucose when switching to low carb.
So importantly, 30% of subjects who had a 31 day mean fasting glucose of greater than 100 on high carb were also the largest responders to the carbohydrate restriction, right? No subjects on the low carb high fat diet had a 31 day average mean glucose of greater than 100. Okay, so these results challenge the existing paradigm. The diets with higher carbohydrates are superior for athletic performance even during shorter duration higher intensity exercise which has been known or thought to be the case for a long time now.
Critically, these results demonstrate that lower carbohydrate intake may be a therapeutic strategy, even for an athlete, to improve glycemic index, particularly in those with or at risk for diabetes without requiring changes in body composition. Like you don’t need to lose a bunch of weight or physical activity, you don’t need to be exercising a ton more.
Interestingly, these results also demonstrate a unique association between glycemic responsiveness to carbohydrate restriction, fat oxidation rates, suggesting that there’s an important relationship here between glycemic parameters and metabolic responsiveness.
Okay, so my sort of interpretation, I was reading a lot of that from the study itself. It’s very scientifically written, a little dry, in my opinion, but my interpretation is this: that the low carb high fat diet produces the same results from an athletic performance perspective as the high carb diet.
And once you’re on that low carb diet for several weeks, weeks, your rate of fat oxidation goes way up. And this is key for both endurance. So being able to burn more fat helps you from an endurance standpoint, and helps improve weight loss, right, you have to burn fat if you want to lose weight, and that the high carb diet can lead to adverse health effects like pre diabetes.
And this is an interesting study because they looked at, you know, seemingly fit healthy men with low body fat percentages, normal body weight, normal BMI, all that they’re all competitive athletes, they exercise more than six hours per week, they didn’t have any medical diagnosis.
They weren’t on any medications, but 30% of them of the high carb group had, you know, blood glucose levels consistent with prediabetes, this is a problem, right? This is consistent with a prior analysis they did, which found that 30% of sub-elite endurance athletes, so this is like your average weekend warrior that’s just out there running for fun, like me, and you probably exercise, less than like six hours per week, had undetected prediabetes when measured via CGM, continuous glucose monitoring devices.
So a prior study has shown that 30% of athletes who seemingly are fit on the outside have this prediabetes condition. So they were fit but not healthy. And this is an important distinction. Do you want to just look healthy on the outside? Or would you rather look healthy on the outside and actually be healthy as a human being from the inside out?
So just because we see somebody on Instagram who looks healthy, they have lean body mass, low body fat percentage they’re ripped, they got abs for days, does not mean that they are healthy. It does not mean that they aren’t having some sort of internal issues or some, you know, condition like prediabetes.
And following the standard dietary advice, which is a very high carb diet, and low in fat, seems to cause metabolic dysfunction in around 30% of the population. And this is just the most fit population, whether you’re very competitive athletes or weekend warriors.
We’re not even looking at the people who do not exercise regularly, who are kind of sedentary. So it’s no wonder that obesity rates are what they are right now here in the US, which is over 42% of the US population is considered obese, over 42%.
This is the first time that here in the US the national rate of obesity has passed the 40% mark. And it’s further evidence of the country’s obesity crisis. The national adult obesity rate has increased by 26% since 2008. I’m gonna say that again, because it’s crazy.
The national adult obesity rate has increased by 26% since 2008.
And I say this all the time, you can’t outrun a bad diet, and this is what I’m talking about. These are very fit individuals who run a lot, who are very competitive, who all appear to be in perfect shape. But there’s more to the story. Your diet matters, what you eat matters. You cannot outrun a bad diet. Sure, exercise is important.
Keep running. Do that for sure, but it’s not going to solve all your health issues. You have to pay attention to the foods that you eat. And all this exercise and all this fitness won’t help keep you healthy unless you also change your diet. It’s up to you to take things into your own hands.
Don’t do what the powers be out there, the food companies, the government or whatever, what they’re telling you to do typically doesn’t work. You have to take things in your own hands. And listen, low carb, it’s not a fad diet. It’s not keto. It doesn’t mean you never eat another grain of rice your whole life, doesn’t involve eating sticks of butter wrapped in bacon, as good as that sounds.
If you want to learn more about my thoughts on carbs, I did an episode about this last week called Carbs Are Not The Enemy. Carbs are not the enemy. There are some carbs that are great and great for endurance athletes and great for weight loss, you just have to do them the right way.
So listen to that episode, for sure it’ll help you, you know, could get a good understanding of that. So if you’re a runner, and you want to improve your health, like really improve your health from the inside out, then making the switch to a lower carb diet might just be what you need.
And as always, I can coach you through all of this. We’ll put together a nutrition plan that fits your lifestyle and gets you to your health and fitness goals. Just go to runningleancoaching.com and click on Work With Me.
Okay, that’s all I got for you today. Love you all, keep on Running Lean, and I will talk to you soon.