The Endurance Diet

Recently I had a disturbing experience on social media. I know, I know. Join the club, right? But This one’s worth sharing, I believe.

Let me start by saying that I’m not naïve in these matters. I’ve been aware for some time that social media is a cesspool of idiocy and viciousness. That’s why I decided last year to drastically curtal my activity on the various platforms. But I held back from taking the even more drastic step of closing my accounts because I kind of need them for business reasons. This left the door open for the mindless savagery of the medium to seek me out, which is precisely what happened last week.

It began innocently enough. An athlete whose name I will withhold for his protection was reading my book The Endurance Diet when he came upon the following passage: “As with workouts, nutrition intake is not necessary during all races. Studies suggest that consuming fluid and carbohydrate enhances performance only in races lasting longer than about an hour. So don’t be that guy or gal wearing a fluid belt in a 5K run!”

Amused by these droll phrases, the athlete shared them on social media. Except he didn’t post the whole passage. Only the last sentence was made public, and let’s just say it was not well received. Minutes after my decontextualized words were broadcast behind my back, my phone started blowing up. After some initial confusion, I came to the alarming realization that I had become the subject of an unprovoked attack by a virtual mob of outraged athletes accusing me of elitism, judgmentalism, and snobbery.

In an odd sort of way, this gratuitous modern-day stoning reminded me of a scene in Megha Majumdar’s novel A Burning. It takes place in the fictional Indian Village of Kokilhat, where a visiting politician watches in horror as a Hindu mob brutally murders a Muslim man falsely accused of killing a cow and eating its beef. By no means am I equating the severity of this imagined incident with that of my online character assassination, but the underlying instinct is identical. The selfsame delirious, hive-minded lust to harm the outsider that drove a horde of bigoted villagers to drag an innocent religious minority down from the thatched roof of his family hut and crush his skull under their boots drove an internet posse of aggrieved fluid-belt wearers to collectively cancel me for . . . for what exactly?

Elitism, yes, but what flavor? It’s not entirely clear, but I have an idea. Had any of my verbal assailants taken the time to level a formal charge against me, I believe I would have been accused of trying to shame slower runners for being slow. This conjecture is based on a reasonable assumption that the practice of wearing a fluid belt in 5K races is perceived as a symbol of being a slower runner. It’s absurd, I know, but less absurd than the only alternative I can think of, which is that, in their eagerness to take offense, my hypersensitive would-be cancellers chose to interpret the orphaned sentence from my book as some form of body shaming, as if a certain fraction of the human population is born with fluid belts attached to their middles and how dare I try to make these poor folks feel “less than” for it!

So, let’s go ahead and suppose that my words were indeed interpreted as an expression of speed elitism, or looking down on slower athletes for being slower. By sheer coincidence, at the precise moment I discovered that I was being burned in effigy in cyberspace, I was working on a blog article titled “How to Impress Your Coach,” in which I explained that good coaches are impressed by two things only—smart decisions and grit—and are not impressed by strong workout numbers. “Currently I coach a half-dozen athletes,” I wrote, “ranging from twenty-something elites to fifty-something mid-packers, and all six of them impress me with approximately equal frequency in these two ways.”

This doesn’t sound like something a speed elitist would say, does it? Nor does anything else I’ve written in the nearly thirty years I’ve been writing about endurance sports. To the contrary, if you were to ask a random athlete who has read and understood all thirty of my published books to describe my shtick, they would probably say something along the lines of, “Matt is all about encouraging everyday athletes to give themselves permission to pursue the sport they love with the same dedication as the elites.” And they’d be right!

Heck, the title of my next book, coauthored with Ben Rosario, is Run Like a Pro (Even If You’re Slow)! Does that sound like a book that a pair of speed elitists would write? No! And if you’re still not convinced that I make no distinction whatsoever between faster and slower athletes, check out my Twitter page, where for the past two years the pinned tweet has read as follows: “Talent should not determine how far you take your athletic journey. Passion should.”

Perhaps the best summation of my professional mission comes not from me but from Knox Robinson,  as quoted in my memoir, Life Is a Marathon. Here’s the relevant passage:

“When I talked to you in New York,” I began, my eyes on my phone to verify that it was recording, “you told me that you created Black Roses NYC because, in so many words, you wanted people in the urban running community to take running seriously—to take it all the way. Can I infer from this that you feel runners who don’ttest their limits are missing out on something?”

Knox sat with the question for a while before he answered. “Yeah, I do feel kind of bad for the folks who don’t take the whole trip,” he said eventually. “Running has unfathomable riches to share. Someone who endeavors to put together the full modern runner’s toolkit and really understand the marathon, beyond just completing it and getting a finisher’s medal, ends up learning more, I think, about himself or herself and what it means to be human. That’s what those tools are for.”

Which brings us back to the statement that I was recently pilloried for on social media. It is a simple scientific fact that carrying and consuming fluid during a 5K running event is completely unnecessary, and not only unnecessary but self-sabotaging, from a performance perspective. It’s fair to assume that most runners who wear fluid belts in short races aren’t aware of this fact. What’s not fair is accusing me of elitism for educating these runners and, more broadly, for encouraging runners of all abilities to pursue maximum performance and to take advantage of proven methods for doing so.

There is such a thing as reverse elitism. It manifests in a very of ways, one of which is a tendency to presume that people who have more of something desirable than you do (money, beauty, education, athletic ability, whatever) look down on those who have less of it. Elitism is real, and it is lame. I have zero respect for the pimple-faced trolls on who brand slower runners “hobby joggers” with such smarmy disdain. But reverse elitism is equally lame and pervasive, and I have no more respect for the passive-aggressive social media vigilantes who baselessly lumped me in with the letsrun trolls than I have for the trolls themselves. The point of this 1,200-word rant? Don’t be lame!

I’m not a total science geek, but I do take an interest in certain scientific fields, including evolutionary biology. My brother Josh, who is a total science geek, being aware of my more casual interest, suggested recently that I check out a book called Good Enough: The Tolerance for Mediocrity in Nature and Society. Written by natural philosopher Daniel Milo, the book is a critique of certain dominant interpretations of evolutionary theory.

Milo’s fellow philosopher (and fellow Daniel) Daniel Dennett has referred to this theory as “Darwin’s dangerous idea,” and with good reason. After all, it is a theory based on concepts that are inherently squishy, hence open to—indeed, requiring of—interpretation. What’s more, these concepts have deep relevance to our lives, and can influence or values, decisions, and policies for better or worse depending on our preferred interpretation. The great cautionary example of an unfortunate interpretation resulting in a damaging application of evolutionary concepts is eugenics, that equal parts vile and idiotic policy aiming to “improve” humanity by exterminating particular segments of it.

The particular interpretation of evolutionary theory that Milo goes after in his book is not nearly so vile and idiotic—merely wrong, in his view. He argues that our prevailing interpretation of evolutionary theory has placed too much emphasis on notions of fitness and function, an overemphasis that in turn is rooted in an inflated understanding of the importance of natural selection, which in turn is rooted in the excessive attention Darwin devoted to the phenomenon of domestication in developing his theory. What gets lost amid these biases, Milo contends, is the degree to which biological features that serve no useful function or confer no survival advantage are retained through sheer accident in the evolutionary process. In order to avoid getting weeded out, a given phenotype need not be better than others; it need only be good enough—and lucky.

The purpose of this article is not to provide a full description of, much less to defend, Milo’s critique of evolutionary theory. It is, rather, to hint at its relevance to endurance training. Because that’s exactly where my brain went as I started reading Good Enough. If you’ve read books of my own including 80/20 Running and The Endurance Diet, you know that I look at endurance sport as a self-organizing system, where competition operates as a ruthless selection mechanism causing training methods and other methods of improving fitness and performance to evolve toward optimum. The point I keep making over and again in my work is that the various major endurance sports have existed long enough, and the competitive stakes have become great enough, that training methods utilized at the elite level have evolved nearly to the point of full optimization, which is to say, to the point where there is very little room for further refinement.

But Milo’s book has shifted my perspective somewhat. Why have world records come down slowly and gradually, for the most part, over many decades? The current men’s world record for 10,000 meters, for example, set last year by Uganda’s Joseph Cheptegei, is 26:11.00. By definition, it is humanly possible to run 10,000 meters this quickly. Cheptegei proved it. Why, then, was Emil Zátopek’s 10,000m world record of 28:54.2 lowered by just 14 seconds in 1956 and not all the way down to where it currently stands? Part of the reason, of course, is that Sandor Iharos, the Hungarian runner who bested Zátopek’s mark, was himself not capable of running 26:11. But what Daniel Milo would point out is that it was surely also because elite endurance athletes are always, in ways they don’t entirely recognize or control, endeavoring not to achieve the limit of human possibility but to be good enough to win today. It can’t be any other way, because endurance sport is subject to the same natural laws that govern all self-organizing systems.

Which makes me think that perhaps there’s a little more room for innovation in training and other methods than I had previously assumed. In fact, this possibility had already been suggested to me by the manner in which the COVID-19 pandemic shook things up within the elite stratum of endurance sport. In a previous blog post, I wrote about how the constraints imposed by this crisis all but forced elite coaches to try different things, some of which led to breakthrough performances and are likely to be retained in the future, long after the limitations that gave rise to them have relaxed. These occurrences showed me just how much complacency and conformity exist in the methodologies used even at the highest level of sport at all times, lockdown or no lockdown.

Let’s not get carried away. Becoming aware of the fact that the Law of Good Enough governs progress in endurance sport does not empower us to operate outside that law and start making giant leaps forward. A law is a law. But for me, at least, I hope this shift in perspective allows me to become a bit more creative and experimental in my coaching. Indeed, I believe it already has.

I don’t really consider myself an expert on anything, but I do know a thing or two about endurance nutrition and training. Nevertheless, I choose to coach on the training side only. If an athlete approaches me with a request for nutrition coaching, I refer them elsewhere. The reason is that I have found nutrition coaching to be frustrating and unrewarding. Whereas training right and eating right are both fairly simple in principle, in practice, eating right appears to be much harder for many athletes. All kinds of self-sabotage keep athletes from locking into a consistent set of healthy and effective eating habits. I’d like to briefly review the major forms of dietary self-sabotage in this post, with a special focus on a new study relating to one of them.

Types of Dietary Self-Sabotage

Perfection Targeting

We all know the expression, “Don’t let perfect be the enemy of good.” Well, in the diet realm folks do this all the time. Who is more likely to eat an entire sleeve of Oreos in one sitting: a person who tries to never eat a single Oreo ever or a person who allows himself or herself to eat one Oreo every day? Science tells us it’s the latter. People who aim for dietary perfection (which is not even definable) tend to exhibit more erratic eating behavior and less -dietary self-control than people who merely aim for “good enough” in their eating habits.

Giving Up

We mustn’t overlook the fact that the single most common form of dietary self-sabotage, even among endurance athletes, is the virtual opposite of perfection targeting: giving up on trying to eat healthily. For most of us, eating healthily requires a concerted effort to break away from the Standard American Diet (SAD), which is the most convenient and comfortable way to eat in the U.S. and, increasingly, around the world. This effort proves to be too much for many athletes. It’s not a crime to eat too much fast food and sugar and not enough vegetables, but it does have consequences, and the one thing I really don’t like to see is athletes convincing themselves that they aren’t paying a cost for giving up and eating the SAD.

Mirror Enslavement

“Mirror enslavement” is my name for a form of dietary self-sabotage that entails focusing too much on outcomes and not enough on process. Scale enslavement is another version of the same phenomenon. Too many athletes decide that, either for performance reasons or aesthetic ones (or sometimes a muddle of both), they need to look a certain way or achieve a certain body weight by any means necessary, and the means they often choose is undereating. It’s much healthier to focus on building and sustaining eating habits that are proven to optimize health and fitness and trust that wherever these habits lead in terms of appearance and weight is where you need to be.

Fad Chasing

A lot of athletes are restless eaters—continuously bouncing from one fad diet to the next, one supplement or superfood or other nutritional magic bullet to the next. These athletes typically assume that the reason they’re always searching is that they haven’t yet gotten the results they want from anything they’ve tried, when in fact it’s the other way around: They haven’t gotten the results they want because they’re always searching. In other words, the true problem is not the diets themselves but the underlying restlessness.

This is not to say that specific fad diets are not also problematic sometimes. The fad diet that’s been causing the most problems lately for endurance athletes is the ketogenic diet, which systematically sabotages the fitness-building process by robbing the body of an essential energy source. Yes, I know that social media is teeming with testimonials from endurance athletes crediting keto for all kinds of miracles, but that ain’t science, and actual science tells us that adopting the keto way of eating as an endurance athlete is the dietary equivalent of riding a bike with square wheels or running with ski boots on your feet.

The Keto Diet

The latest scientific takedown of the keto diet is a study led by the legendary Louise Burke of the Australian Institute of Sport and published in PLoS One. Burke’s team actually repeated a previous experiment they’d done involving elite racewalkers, adding a twist that was intended to address criticisms of the original study lobbed by keto advocates who didn’t like the findings. Twenty-six elite race walkers were separated into two groups, one of which was placed on a high-carb diet (8.6 grams per kilogram of body weight daily) and the other on a ketogenic diet (<50 total grams of carbs daily) during a 25-day period of intensified training. Physiological and performance testing were done on both groups before and after the intervention.

What was different about this experiment was that, instead of doing the second performance test immediately after the “fat adaptation” process, the keto athletes were given 2.5 weeks to replenish their muscle glycogen stores by eating more carbs. In principle, this enabled them to have the best of both worlds, retaining the increased fat-burning capacity they’d earned through keto eating without being hamstrung by low carbohydrate availability.

The keto diet did achieve its objective of increasing fat-burning capacity in the athletes who followed it, their peak rate of fat oxidation during exercise jumping from 0.6 g/min to 1.3 g/min over the course of the 25-day intervention and remaining elevated through the replenishment period. However, as in the first experiment (and in other studies), this seemingly beneficial adaptation was not really beneficial at all, resulting in a sharp increase in the energy cost of walking at race speeds. On average, performance in a 10K racewalk event improved by 4.8 percent among athletes who followed a high-carb diet and decreased by 2.3 percent among those who were fat-adapted. Oops!

Long story short, be wary of fad diets. Elite endurance athletes eschew them, for the most part, and I encourage you to do the same. Indeed, emulating the core eating habits widely shared by elite endurance athletes (as described in The Endurance Diet) is a great way to avoid all forms of dietary self-sabotage.

I have too many ideas. I could write two books a year for the next 100 years and still not get around to writing all the books I have ideas for, let alone execute on my non-book-related ideas. I even have an idea for a book called 100 Books I’ll Never Write. Yeah, it’s that bad.

Still, I’d rather have too many ideas than not enough. In this post I would like to share one of the ideas I don’t have time to do anything about in the hope that it will inspire someone else (maybe you!) to take it up. You already know what it is because I put it in the headline.

So, to begin: Chances are you have a Strava account, and if you don’t, you at least know what Strava is: an online platform that allows endurance athletes to share their training and racing exploits with other endurance athletes. It takes advantage of the fact that most endurance athletes are proud of their workouts and races and want other people to know about them.

In my view, though, the best use of Strava is not bragging about your own training and racing but following the training of highly successful athletes. As long as you do so in an intelligent way (not a monkey-see-monkey-do way), observing how the best athletes approach fitness development can serve as a useful source of information to guide your approach to same. This is especially true if you follow a number of such athletes, as clear patterns will emerge (e.g., adherence to the 80/20 principle of intensity balance). Most of the best endurance athletes do most things right in their training, so you can trust that these patterns represent true best practices in endurance training.

For some time now I’ve wished that there existed a dietary analog to Strava. I think it could help athletes in a way that’s similar to what I just described on the training side. Just as most athletes fail to follow best practices in their training, most athletes also fail to eat optimally. The most common mistake is simply eating too much junk food and not enough healthy food (i.e., the same mistake most nonathletes make with their diet), but a lot of other athletes make something close to the opposite mistake of being too restrictive with their diet. Indeed, if I had a nickel for every athlete I’ve encountered over the years who paid a significant cost in fitness and/or health resulting from being too restrictive or obsessive with food in one way or another, I would live in a much bigger house.

Elite athletes seldom make this mistake. There are exceptions, of course, but the vast majority of elites, particularly those who perform at the very highest level for extended periods of time, tend to follow a balanced and inclusive that is basically “normal” except in its overall quality. If you’re interested, you can learn more about the characteristics of this way of eating in my book The Endurance Diet. In any case, the point I wish to make here is that it would be really helpful if large numbers of elite endurance athletes were among those sharing the specifics of their daily eating with other athletes on a Strava-like platform.

If you’re a cynic, you’re right now thinking that it’s a lot easier to lie about what you eat than it is to lie about your training, and that people are highly prone to lie—even to themselves—about what they eat. I agree. As yet, there is no dietary equivalent of a GPS running watch that automatically uploads the details of your last meal or snack, and any nutrition scientist can tell you that dietary self-reporting is notoriously unreliable. There’s no denying these facts, but I believe it’s possible to account for them in a manner that would preserve the potential value of a Strava-for-diet type of service.

Photos would be a piece of it. If you can’t upload photographic evidence that you ate what you say you ate, then you didn’t eat it. This would do nothing to address the problem of not sharing the things you eat that you don’t want others to know you eat, but the platform could do so fairly easily by recognizing a small number of its participants as “verified influencers.” These individuals would be recruited from among the platform’s most widely followed participants and would be offered modest compensation in exchange for agreeing in writing to provide complete and accurate information about their diet. This mechanism would serve not only to give participants confidence in the information presented by the influencers but would also incentivize aspiring future influencers to provide complete and accurate information about their own diet.

I’m not so naive as to think a Strava-for-diet platform that included such measures would spare every athlete from going down the wrong path with their diet. But I do believe its net effect would be positive, because it’s a simple fact that most of the most successful endurance athletes eat in a healthy way that’s not too restrictive, and the platform I envision would make this fact apparent in a way that it’s not currently, So, anyway, if you like this idea and you’ve got time on your hands and some capital, make it happen.

The other day I had an interesting conversation with an athlete I coach who is training for an Ironman 70.3 event that will take place on the same weekend as the Ironman race I’m training for (specifically the weekend of May 10-11, 2019). In explaining to me why he had done the bare minimum of swimming within a range of options I gave him during a holiday trip, he said that the hassle of doing more didn’t seem worth the extra second or two per 100 meters he might gain thereby.

Although I found no fault with this reasoning as it applied to my client, when I turned it around and applied it to myself, it struck me that my attitude is rather different. Simply put, I am fighting for every possible second in my  preparations for Ironman Santa Rosa. Whether it’s through training, nutrition, equipment, psychology, logistics, or you-name-it, if there’s something I can do (safely and legally) to shave even one second off my finish time, I’m doing it.

Why the no-stone-unturned approach? Several reasons. One is that I feel I must take this approach to achieve my goal of earning an Ironman World Championship qualifying slot. I am not talented enough, nor is the competition weak enough, for me to be able to coast to Kona. Indeed, in my first Ironman I missed out on the last qualifying slot in my age group by 23 seconds! Another reason is that I enjoy the challenge of trying to identify and execute all possible means of improving my performance. For me it makes the preparatory process a more stimulating game than it would be if I were to set a lower bar. And, unlike my client, who travels a lot for work and has a new child, I have the time and opportunity to fight for every second. I’m not a parent and I don’t hold a real job, and indeed it’s sort of my job to train and compete, so, why not?

In this post, I thought I would share a few examples of what I’m doing in the effort to shave every shavable second off my Ironman Santa Rosa finish time.

My Ironman Training 


Swimming is my weakness as a triathlete. But nor am I a beginner, and the experience I do have gives me advantage of knowing that the most effective way to become a better swimmer is to focus intensively on technique improvement by working one-on-one with a good coach. I’ve been fortunate to find a very good coach in Mandy McDougal of Mind Body and Swim. Her pragmatic methodology suits me well and reminds me a lot of my own coaching style. She’s big on evolving the stroke you have rather than imposing some one-size-fits-all notion of perfect technique, prioritizing the most impactful changes and making them stick through basic drill sequences.

Here are a couple of her videos that concern technique elements I have benefitted from especially:


I make a four-hour round-trip drive every two weeks or so to benefit from Mandy’s instruction. Whatever it takes!


The primary application of my no-stone-unturned approach to cycling has been spending lots of money. My main expenses so far have been a high-end indoor power trainer (Wahoo Kickr Core) and a high-end time-trial bike (Felt IA2). Past experience has taught me that I get a lot more fitness per training hour when I do most of my cycling indoors, where I can perform very precisely controlled workouts. Already I’ve seen benefits from using the Kickr two to three times per week.

As for the time-trial bike, as much as runners like me like to think it’s all about the engine, it’s really not. Outdoors I travel 3-4 mph faster at the same power output on the Felt IA2 than I do on my road bike. I’ll likely gain a few more tenths when I shell out another couple of grand on race wheels. And, to further ensure I get the most out of my new machine, I’ve had not one but two professional fittings done at Revolutions in Fitness in Palo Alto.


Running is supposed to be my strength, but a nagging groin injury has made it anything but that lately. Fortunately, the injury does not stop me from running; it just prevents me from running fast (for now). Fortunately as well, I won’t need to run particularly fast in my race to achieve my goal. If I swim and cycle as I hope to in Santa Rosa, a marathon split of 3:20 should get the job done. That’s 7:37 per mile. In the next-to-worst case scenario (the worst case being that the groin degenrates over the next four months), I will run no faster than this in training and enter the race with one-dimensional running fitness—plenty of endurance but no speed.

I take some comfort from having been in this position before. When I trained for my first 50-miler in 2016, a bothersome Achilles prevented me from doing any faster training until within a few weeks of race day, and I still did okay. In a nutshell, leaving no stone unturned in the running dimension of my preparation for Ironman Santa Rosa will entail doing very large amount of very slow running.

One of my major training goals in general is to make the Ironman distances seem completely unintimidating. In 2017, I ran eight marathons in eight weeks, and by the end of this experience 26.2 miles was ho-hum—a major reason I was able to set a marathon PR later in the year. I’m now attempting to do the same thing with all three triathlon disciplines in my current Ironman preparation, for example by doing 100-mile-plus bike rides two to three times per month.

Other trainings

Obviously, nutrition and weight management are hugely important in Ironman training and racing. But I’m not doing anything extreme in these areas for the purpose of shaving seconds off my finish time at Ironman Santa Rosa. To the contrary, I am studiously avoiding doing anything extreme. In my experience, triathletes who otherthink nutrition, become weight-obsessed, and/or go in for unbalanced diets such as the high-fat low-carb fad more often get slower instead of faster. So, for the most part, my approach to nutrition and weight management will consist in simply continuing to eat like the pros, as described in my book The Endurance Diet.

Course familiarization is another element of my strategy of fighting for every second. I plan to make two trips to Santa Rosa ahead of race weekend to ride and run the course, and I’m even considering renting a small boat and paddling the swim course as soon as the buoys go up a couple of days before the event so I can capture a clear picture of what I will see from the surface during the swim.

From my inspection of the online course maps, it appears there’s a fairly lengthy run—likely on concrete—from the swim exit to the transition area. If I’m able to confirm this, I’m going to practice a little barefoot running on concrete to callous the bottoms of my feet, enabling me to shave a few seconds there. And, of course, I will practice mounting my bike with my shoes already clipped in the pedals and dismounting barefoot, as the pros do.

Not for Everyone

By no means am I recommending my no-stone-unturned approach to Ironman preparation to everyone. But I am having a blast with it and I wouldn’t want to see any other likeminded age-group triathlete shy away from it just because he or she is not paid to race. I mean, so what?

A few months back, the following tweet from triathlon legend Dave Scott caught my eye:

It always amazes me how folks fear a new paradigm for sports nutrition. Unless you own a sugar-based nutrition company, why WOULDN’T you experiment w/ #LCHF It works when implemented properly … even at high intensities.

I’m not sure whether Dave meant this question rhetorically (after all, there’s no question mark), but I took it literally and personally. As a competitive endurance athlete who takes seriously the role of diet in endurance performance, I had to ask: why haven’t experimented with a low-carbohydrate, high-fat diet?

The answer, I decided, could be distilled to a single word: risk. I believe that switching from my current way of eating to LCHF would carry an unacceptably high risk of causing problems. For me, a better question than the one Dave asked is, why would I experiment with LCHF? My current diet does not limit my athletics in any way that I can identify. When I train harder I get fitter and when I rest I recover. I feel good physically pretty much all day every day. At age 47 I am as lean as I was when I was 27. If it ain’t broke, as they say. . .

Meanwhile, on the other side of the equation are a host of negatives outcomes, some guaranteed, others likely, that are associated with jumping onto the LCHF bandwagon. Nearly all athletes who do so feel like crap initially and experience a significant decline in training capacity and performance. Some come out the other side eventually, others don’t. The diet is extremely restrictive and monotonous and socially isolating. (“Hey, Brad! Do you want to come out to dinner with us? We’re going to that Italian place.” “Uh, well, you see. . .”) And the physiology is inescapable: Eating LCHF will make your muscles better at burning fat and much worse at burning carbohydrate, hence more dependent on fat, which requires greater amounts of oxygen to metabolize, thereby increasing the energy cost of moving at any given speed.

Those are the guaranteed outcomes. The potential outcomes that seem to affect some but not all LCHF eaters include unfavorable changes in blood lipids, mood disturbances, vertigo, skin problems, caffeine intolerance, and panic attacks. The long-term health effects of eating in this extremely unbalanced way are largely unknown, but a recent, large epidemiological study found that, on average, men and women who get less than 40 percent of their daily calories from carbs die four years younger than do those who get between 40 and 70 percent of their calories from carbs.

Elite endurance athletes don’t shy away from this diet because they are afraid of news things. To the contrary, no group is more eager to gain a competitive advantage through early adoption of new methods. Instead, the vast majority of pros choose to keep their diet carb-centered because, with their livelihood depending on their performance, they can’t afford to try “new” things with such an obviously poor risk-reward ratio as LCHF.

A recent case study indicates they are wise to do so. For a period of 32 weeks, a professional triathlete who switched from his normal, lacto-ovo vegetarian diet to LCHF was monitored by Spanish exercise physiologist Iñigo Mujika. Within the final third of this period, the athlete raced three times, finishing 18thin a half-Ironman with his worst time ever for that distance, then finishing 14thin a full Ironman with his second-worst time ever for that distance, and then DNF’ing his next race. Having had enough of LCHF by this point, the athlete went back to his normal diet. Just five weeks later he took second place in an Ironman.

This case study challenges several tenets of the LCHF doctrine. One of these is the notion that only athletes who, as Dave Scott suggested, fail to implement the diet properly fail to benefit from it. But Mujika’s subject was an experienced and knowledgeable professional athlete with all the attending resources and scientific support. Mujika reported 95 percent compliance with the diet’s strictures across the 32-week period. LCHF advocates also like to explain away the disasters that so commonly befall athletes who try it by claiming they didn’t give it enough time. I’m sorry—if 32 weeks isn’t long enough, then forever isn’t long enough.

The primary reason this particular athlete switched to LCHF was that he suffered from debilitating GI issues during races, and it is another popular tenet of the diet’s doctrine that it cures these issues. The subject of the case study experienced no improvement in GI symptoms during races on LCHF. This shouldn’t surprise anyone, as the two main causes of GI distress during long endurance events are the stress of the events themselves and a genetically-rooted susceptibility, neither of which can be changed by any diet.

Here is where LCHF advocates predictably say, “But this is just a case study. We’re talking about one athlete!” The problem with this objection is that each of us is one athlete with only one body to care for and limited opportunities to compete each year. If LCHF works best for 90 percent of athletes, it is remarkably unlucky that the athlete chosen for this case study was among the few for whom it doesn’t work. Is this the assumption you want to make as an athlete who cares most about your fitness and performance? I think it’s far more reasonable to see this case study as yet more firm evidence that LCHF is risky.

This was not intended to be another one of my rants against LCHF for endurance athletes. The point I want to make in referencing it is that, although this way of eating does appear to work okay for some athletes, it is high0risk. So are a lot of other diets and nutritional measures that endurance athletes try in pursuit of better performance. Reflecting on Dave Scott’s tweet caused me to realize that the approach to endurance nutrition that I advocate is really a risk-minimization approach.

If you adopt and follow the five habits of the Endurance Diet, you will not and, indeed, cannot go off the rails in the way that so many LCHF athletes, plant-based athletes, and other athletes who choose unbalanced diets of one kind or another do. To refresh you memory, these habits are:

5 Habits of Endurance Diet


Consistently including all of the major food types in your diet minimizes your risk of being taken down by one of the nutritional holes that open up when things like meat/fish and grains are eliminated.


This habit is about centering the diet on unprocessed, natural food types (e.g., nonfried vegetables) and limiting intake of processed foods (e.g., refined grains). Many LCHF eaters pay no attention to quality, loading up on processed animal products such as cured meats and mayonnaise that have proven negative health consequences.


It’s just a fact: The safest place to start with your macronutrient balance, if you’re an endurance athlete, is carb-centered, which simply means including high-quality carbohydrate-rich foods in most meals and snacks. Lots of LCHF eaters claim they switched to this way of eating because a carbohydrate-centered diet didn’t work for them. This claim never stands up to scrutiny. It was sweetsand refined grainsthat didn’t work for them, not carbs in general. I’ve never dealt with an athlete who couldn’t make a carb-centered diet work for him or her by combining it with Habit #5 (below).


This habit is about relying on the body’s built-in appetite signals to regulate the amount of food you eat instead of counting calories. In my experience, calorie-counters are at much greater risk of eating too little, which is far more detrimental to endurance performance than eating too much.


Most extreme diets are one-size-fits-all. The Endurance Diet is not, and this is another way in which it manages risk. Do grains generally not agree with you? Fine. Then practice Habit #3 (“eat carb-centered”) by getting most of your carbs from fruit and starchy vegetables. Forcing yourself to eat exactly like every other follower of whichever named diet you choose to follow brings with it great risk of forcing yourself to do something that doesn’t work for you individually.

Woven into these five habits are two further principles that also serve to minimize risk in eating for endurance. Framed as edicts, they are (1) Keep things as simple as possible and (2) don’t change anything in your diet that you don’t both want and need to change. The more unnecessarily complex you make your eating habits (e.g., intermittent fasting) and the more things you change (e.g., completely tossing out your current habits and going all-in with LCHF or some other unbalanced one-size-fits-all) diet, the likelier it is that you will create a health- or fitness-harming new problem that did not exist previously.

A certain amount of risk is inherent in endurance athletics. You have to train hard to attain peak fitness, and hard training brings with it the risk of injury and the risk of illness. Don’t let your diet compound these risks unnecessarily.

Last week I received an email message from Dawn, a runner who had just purchased The Runner’s Diary, a book I authored back in 2008. Maybe “book” isn’t the right word. As the title suggests, it’s mainly just a training log, but it does offer some training and nutrition tips. Dawn told me that, although she loved “the feel” of the book, she was concerned about how old it was. The purpose of her message was to ask me if the information in it was still current.

The idea that certain training methods and nutritional beliefs become outdated is widespread in the running community. Many runners share Dawn’s concern about following training or nutritional guidance that isn’t “cutting-edge,” so I figured I would address the subject in this post.

Evolution of Training and Nutritional Methods

It is an unquestionable fact that the phenomenon of obsolescence in training and nutrition practices is real. Scientists, coaches, and elite athletes have been known to come up with new methods that work better than those that are regarded at the time as best practices. However, the mere fact that a certain training method or dietary practice has been around for a long time does not automatically mean it has been improved upon. I suspect that the influence of technology on modern life has given many runners false expectations about the evolution of training and nutritional methods, and I think it’s important to correct this misapprehension because it causes many runners to adopt inferior methods simply because they are (or seem) new.

The next time you’re watching a television news program and you hear something like this—“Researchers believe they are five years away from being able to grow fully viable human organs in vitro,” or “Space engineers anticipate having the technology to execute a manned mission to Mars by the year 2025”—stop and think about it for a moment. Whether or not these specific predictions turn out to be accurate, what is certain is that we can count on technology to get better and better every year. There must be some final limit to innovation, but it’s nowhere in sight. Everyone living in first-world societies today has absolute confidence that the medical, transportation, communication and other technologies that represent the bleeding edge today will be outdated in the future.

It is this environment that causes runners to vaguely expect training and nutrition methods to do the same. But there’s a crucial difference between technological and endurance sports domains, which is that endurance methods operate on the human body, which is not a piece of technology. Although (contrary to what many people believe) our species does continue to evolve, it is a very slow process compared to advancements smartphone features and robotic surgery techniques. For this reason, the optimal methods of maximizing endurance performance cannot just keep getting better. Once the best ways to train and fuel the human body for distance racing have been discovered, it is impossible to improve upon them further until and unless the human body changes enough for different methods to become optimal.

For example, in the 1950s, New Zealand running coach Arthur Lydiard discovered that a training system combining very large amounts of low-intensity work with small amounts of high-intensity work was more effective than any training system that had been tried previously. In the 60-plus years that have passed since this discovery, no other innovator has come up with anything better, and none ever will. Hard limits such as the maximum stress tolerance of various organs and tissues guarantee this.

There’s a parallel situation on the diet side. In The Endurance Diet, I identify five dietary habits that are practiced almost universally by top endurance athletes all over the world. Framed as rules, they are:

  1. eat everything
  2. eating quality
  3. eat carb-centered
  4. eat enough, and
  5. eat individually.

The book includes an historical analysis that shows these habits were not universally practiced by elite endurance athletes of past generations. Rather, they spread in much the same way Lydiard’s training approach did as it became clear these habits were essential to the maximization of endurance fitness. And as much as certain fad diet fanatics wish to believe otherwise, these habits will never be replaced by superior innovations, because again, the human body is not a smartphone.

Let me also repeat, though, that small but important innovations in endurance training and nutritional methods continue to occur. Depletion workouts are one example. I encourage athletes at every level to take advantage of any and all such innovations that achieve substantial penetration in the elite echelon and solid scientific validation. Just don’t fall for fads that contradict current core best practices in training and nutrition merely because these fads are (or seem) newer.

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