Do You Burn Fat or Sugar?

Do You Burn Fat or Sugar?

Matt Cooper is our Resident Biohacker and Lead Science Writer here at Warrior Soul. He’s also the co-author of Warrior Soul Keto Camp, along with Chris Albert. You can find out more about Warrior Soul Keto Camp at

Do you ever sit and ponder life’s great question-am I a fat burner or a sugar burner?

You don’t? That’s okay. If you want to reserve moments of silent reflection for other things, I understand.  But if you’re not going to ask yourself, then I will, for your own good.

Learn about how you can experience ketosis in a minute!

Do YOU burn fat or sugar?

Let’s dive right in and do some simple detective work to find out what the status is on your metabolic operating system and whether you’re burning fat or sugar (glycogen, really) for energy.

I often get asked why there’s such a disconnect in views when it comes to carbohydrates-starchy carbohydrates that have a significant impact on blood sugar-not fibrous vegetables.  Most of the time, carbophiles-bodybuilders, vegans/vegetarians, endurance athletes, the U.S.D.A., M.D.’s R.D.’s, etc.-perpetuate nutritional dogmas that involve consumption of many carb-based meals, spread throughout the day.  They deride low carbers (not that all sects of these people are fundamentally right, either-especially the carbophobes)-insisting that the body’s operating system is glucose dependent.  My belief is that this stems from a core misunderstanding of carbohydrates and the body’s preferred operating system.

They believe that glucose is the best fuel-the top shelf stuff-for your body’s o.s. to properly function and they do everything they can do avoid running out of gas.  Hell, I used to be one of these carbophiles-my then-archane belief system supported by both bro science and the 1980’s-based diet info still sticking to the walls of academia like toxic mold. It’s time to change the way we think about fueling our bodies for human optimization and rewrite the low-rent garbaj that’s taken over the healthcare system.

The reality is that the body’s preferred source of metabolic fuel is fat.  It’s been that way for most of our evolution.  But if I had a dollar for every rent-a-trainer or health brofessional that insists we eat five to eight meals (many or all carb-containing) a day to keep our blood sugar up so our bodies don’t crash and our muscles don’t cannibalize themselves, I would wipe my ass with $20’s.  It’s like they think God kills a kitten every time we don’t eat a meal every two to three hours or something.  I don’t get it.  Information that contradicts these notions continues to stockpile.  Let’s examine this faulty belief system…

Fractured Logic

The underlying belief is that glucose is the overwhelmingly preferred fuel source at the cellular level.  We can only store so much as glycogen in both liver and muscles.  So we need to have this I.V.-style system of feeding our bodies carbohydrates every so often-that keeps our blood sugar high, our brains running, maintains body functionality, and keeps our muscles well-fed.  If we don’t, our blood sugar crashes, we don’t function right, and we induce the monster under every bodybuilder’s bed-catabolism.  Not to mention, we need to introduce high volume training regimens to burn off this fuel….but wait-we also have to keep feeding ourselves like this to maintain this type of regimen.  If that sounds exhausting, it’s cause it is.  That’s the irony in all of this.  This self-fulfilling prophecy isn’t a shortcut-it’s like taking the scenic route that isn’t pretty and doesn’t get you to your desired destination, either.

“Walter, what is the point, man?”

Sorting Through The Moving Parts

My point, dude, is that we need to end this once and for all.  It’s time to reframe our lens of the human metabolism.  Ancestral eating reflects our linearity of our human evolution, which lead to our current genome.  The built-in expectation is simple: we run best on more fat.

Though exceptions exist-genetic and athletic situations, mainly, the reality is that most of the population would do well to empty their carb clip a bit and focus less on reloading it so aggressively and egregiously.  Changing your metabolic o.s. to shift more towards glucose burning can actually reprogram your genes in a harmful manner-as Mark Sisson, author of The Primal Blueprint, points out, “your genes will eventually get the signals to up-regulate the enzyme systems, pathways and receptors involved in accessing and burning fat for energy.  Of course, that doesn’t make it right, but it sure does make it appear as if glucose is king.”  You should know, and he also does mention, that this can lead to some very damning issues, such as fat gain, insulin resistance, energy issues, mood swings, etc. and is witnessed as a common denominator in many metabolic disorders/diseases.

Glucose simply isn’t needed en masse under resting states and under most common activity thresholds; rather we should view our level of carb feeding as a situationally-dependent variable.  Although our bodies can utilize glucose for energy most easily, it doesn’t mean it should be.  A shift in carbohydrate oxidation via excessive exogenous carbohydrate consumption may make it appear as if your body prefers carbs.  But your body burns fat more efficiently and without the same barnacle issues that accompany being a carb burner.

Metabolics Through An Evolutionary Lens

The reality is that through two and a half million years of evolution, mankind has had a limited access, and thus consumption, of carbohydrates.  This lead to fat and protein being the dominant macronutrients.  Our biological mechanisms had to adapt to being able to access stored body fat for fuel as a means of running an efficient operating system.  To go back to Sisson’s work for a moment, our storage capacity in our glycogen clip is so small that surviving off of a largely carbohydrate diet wouldn’t have been possible.  Contrast that with our much larger threshold for fat storage and its efficiency as an o.s.: “It was predominantly fats, ketones, and the minimal infusion of glucose via gluconeogenesis that got us here.  Dietary carbs were insignificant.”  Again, we’re talking about starchy carbs in this case, not fibrous vegetable carbs.  If our goal is human optimization-peak health and performance-our own evolution if you will-our eating strategy should reflect our human genome, which ancestral eating supports.

Our genetic default settings want us to be able to consume fat and utilize stored fat for energy on a regular basis, and/or during times of fasting, with the understanding that the body can manufacture glucose if need be.  Most activity can be fueled in this fashion, and the body-brain and all-functions optimally to boot.  When leveraged with correct food choices, it also can be utilized as a preventative support agent against many metabolic disorders and disease.  I would even argue that fat adaptivity, as a result of proper ancestral dieting, allows for a larger margin of error and thus, a degree of flexibility in the calories in/calories out model for weight management and body composition changes.  Again, I’m not anti-carb at all-I just believe in using carbohydrates as a situational variable in my methods, rather than as the necessary fuel-all must that many of my peers do.  I’m also pro high (properly-sourced) fat.

Unfortunately, this carb discussion is really a side effect of nutrition education at large.  As scientists, shouldn’t we be trying to prove ourselves wrong?  As in like…all the time?  Instead of continuing to perpetuate the inputs and outputs without ever examining the ‘why?’ and ‘how’ in the middle of the metabolic equation, why not try to understand what’s going on in the middle?  In the black box, if you will.  I hope I’ve shed some light on the matter.  On a larger scale, I believe it’s time we rethink the lens in which we as a society view nutrition, from academia to ground zero.