In late November 2022, Outside online published this article, “4 Surprising New Insights on Fueling for Endurance Sports” as part of Alex Hutchinson’s Sweat Science Column. I wanted to do a review of this article, because it’s important that you are fully informed. 


Because I've gone down the rabbit holes of fat adaptation and, thus, have inside knowledge, I can’t help but chuckle at the first paragraph because he quotes one of the world’s leading researchers in sports nutrition, Louise Burke; “at the coalface” . Like most of today’s sound-bites there is a lot missing by just quoting three words. Here is the full sentence: 

“However, those at the coal-face of sports nutrition can delete fat loading and high-fat diets from their list of genuine ergogenic aids for conventional endurance and ultra-endurance sports.”

- Louise Burke, “Fat adaptation” for athletic performance: the nail in the coffin? J Appl Physiol 100: 7–8, 2006;doi:10.1152/japplphysiol.01238.2005

However, there is a fly in the ointment because Dr. Burke essentially retracted this statement roughly a decade later when the first paper to come out of the FASTER Study “Metabolic characteristics of keto-adapted ultra-endurance runners” published.

As you can see these three words are taken from a very strong and clear statement as if it were fact. And, most people would take it as just that, a non-disputable fact, coming from a credentialed expert like Dr. Burke.  Those three words yield clues to the underlying bias of this article and why it’s important you think critically, analytically and, most of all, ask questions OR listen to us, who can’t stop asking questions and testing the narrative.

Myth 1 - Dial Up the Carbs

Dial Up the Carbs is the first key insight. I’m not disagreeing with this insight per se, because OFM recommends doing precisely this as part of our “Strategic Carbohydrates” concept. Where we depart is just how much and that can vary widely.  For example, Elite Marathoners “get 85% of their in-race energy from carbohydrates” is mis-leading, very mis-leading. 

  • First of all, how many of us are Elite Level Marathoners. 
  • Second, how often as a percentage of their total running volume are Elite Marathoners racing where they need that extra push from carbohydrates? Many of the elites do a majority of volume at levels where fat is the primary energy substrate. So are you going to fuel for all of your training as if you are racing? 

The BIG problem in this is the message the author is sending is it is all about the carbs and lots of them. This is completely out of context in the real world of training, even in the conventional high carb space. Nobody, including the Elites, is racing all the time. Fat metabolism plays a much larger role than Mr. Hutchinson recognizes. Not only does it provide a significant source of energy for training and racing, it is fat metabolism that ‘makes the magic happen’ for the hormesis required to get stronger, fitter, faster. 

Ironically, by training to expand fat metabolism you also are preparing your cardiovasculature to use carbs at threshold levels of intensity. This is because of the need for twice the oxygen per ATP produced using fat versus oxygen. Such training allows for the body to move more oxygen which, on race day, can be harnessed by massive energy via glucose as needed. 

Fat Metabolism Is A Source of Glucose

Another significant source of glucose not mentioned is via fat metabolism. When fat-adapted, your liver synthesizes glucose from fat to meet the metabolic need through a process called gluconeogenesis without catabolizing protein. Insulin from consuming too many carbs prevents this from occurring in high carb athletes essentially preventing them from accessing another reservoir of glucose. This is the pathway which caused the Low Carb Diet Cohort in the FASTER Study to replenish their glycogen stores without taking in any carbs instead of that carb rich post exercise drink!

Point is fat metabolism needs to be prioritized for most of your real world training and racing. Paretto’s Law of 80/20 is a good place to start.

Myth 2 - Don’t OD on Veggies

Before diving in, allow me to frame this topic. Dynamics is one of the key ‘Teachable Points’ of OFM. There is an ebb and flow to everything in Life. So food shifts around in both calories, macros and types of foods consumed. Even a guy like Jeff Browning takes in 80-90% carbs in the form of gels, liquid and the honey and/or orange juice that’s in every pouch of VESPA during a 100 miler, . . . BUT, it only comprises less than 20% of his caloric needs. 

With respect to vegetables and fruits, nothing insightful here if you are doing OFM. We actually use the strategy of consuming non-starchy vegetables to fill you up and attenuate hunger in our programs, because they have low energy content, but move away from them prior to competition. This subject is actually well studied by the US Air Force and NASA. Ask any SR-71 or U-2 pilot what happens if they eat a salad and go flying at high altitude?  There is not much different than a marathoner who does the same.

Myth 3 - Eliminate Dead Weight

Of course eliminating dead weight is always a good idea but oversimplified. Getting your GI tract in optimal condition needs to be the first and underlying priority because this creates the environment for digestive flexibility so you can shift to mostly low fiber foods in the few days prior to a competition where a bathroom break is not a desirable thing. 

And what should you be consuming when you lower your fiber intake? Energy and nutritionally dense animal based food sources along with those ‘Strategic’ carbs. Not only do they contain protein but, in their natural state, plenty of fat so you are not burning through your carb stores. 

What was not mentioned was the subject of fat & fluid weight. When you optimize fat metabolism you BURN FAT instead of storing it and you do not have that glycogen bloating of a high carb athlete whose body is dependent upon those glycogen stores because for every molecule of glycogen stored, 4 molecules of water go with it! As our athletes know, this can also add up to several pounds of fluid weight you don’t need. 

Myth 4 - Pump Your Iron Up

“She also noted some key parameters to monitor on an ongoing basis: vitamin D, vitamin B12—and iron.”

Vitamin D, B12, Iron deficiencies?  These are addressed up front with OFM so they do not become a problem. High dose Vitamin D , Magnesium and Liver capsules which are part of our OFM Foundation Supplement Pack, whole animal eating and fat adaptation all combine to ensure you don’t have to worry about these issues. (unless you have an underlying condition). Simple. Scientifically sound. Relatively easy to execute to prevent rather than address these issues.

With the popularity of plant based diets, fear of skin cancer and high carb diets for athletes this is yet another case of misguided good intentions. It is a cascade effect of too much sugar in the diet, yes, carbs are sugar as far as your body is concerned.  Too little animal based foods for bioavailable heme iron and essential B-12 along with too little skin exposure to sunlight all impact our overall health. Additionally, when glucose is given metabolic priority in an effort to burn it off your skin cells are more prone to skin cancer than when they are metabolizing fat. 

The Washup

I don’t need to tell you that a lot of sugar in the diet is a bad idea. You know this. Carbohydrates become glucose, blood sugar, so promulgating the consumption of a lot of carbs based upon what elite marathoners are doing in race is simply not going to end well for most people who follow this advice.  There are going to be a host of ‘unintended consequences’ in the long haul, that is why athletes find it hard to keep competing in their late thirties and up.

One of the problems here is the binary war going on between the high carb camp and the keto camp, and this makes it easy to promote a high carb approach for performance athletics, because most people are going to simply feel terrible trying to push their performance above a certain level on keto. Bring in the carbs and it works like magic, except you will not have those ‘unintended consequences’ down the track of high carb consumption. Both camps are intransigent and stuck in their ‘Science’. There is a better way. One that focuses on YOU, the Individual.

Like the Allan Savory says, “If you look at the breakthroughs in science almost always they don’t come from the center of that profession they come from the fringe.” This is where we’ve resided; at that very edge of Human Performance. We take what we learn at the very fringes of Human performance to develop doable and sustainable strategies that get sustainable results. 

It is an individualized and dynamic approach that can’t be commoditized and it begins with your native physiology, the one that burns fat. 

When carbs are your primary fuel you will pay the price with your health which will ultimately also impact your performance, however, when you optimize your fat metabolism and use carbs ‘Strategically’ when your body needs them (which is way less than you think), you will not only reach “Higher Health & Peak Performance” but optimize your longevity for that ultimate endurance event we are all entered in called Life!

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