Is Carb Loading Really Still A Thing?

Apparently so.

(And as I’m finding, not just for runners and endurance athletes, but for moms to be!)

Given that the article that prompted me to write today’s post was a recent one published in Runner’s World, I’ll focus today on the misconception that runners / endurance athletes not only need carbs, but a heck of a lot of carbs.

While I certainly was not surprised at the contents of the article, given it’s title, How to Carb Load for Your Next Race (1).

The article starts out with a seemingly logical explanation of why we ‘need to carbo load’ as well as the looming demise of race performance (GI distress, hitting the wall and cramping amongst other easily avoidable outcomes) that is sure to unfold, dare we not fill our boots with pasta, bread and brownies the night before a race.

Then, the by-the-book recommendation from the USDA panel on sports nutrition, as incorporated into the curriculum taught to many an aspiring dietician that we should aim for “4 grams of carb per pound of body weight for two to three days prior to an event. That means a 150 pound runner should aim for 600 grams of carbs for his or her loading phase”.

This would equate to 2,400 kcals just coming from carbohydrate alone, which begs the question, is this hypothetical person supposed to then add on more calories to supply even a trace amount of protein or fat, or subsist solely on carbs for three days?

There is a sample menu provided as well, of which the mere thought of consuming made me sense the subsequent lethargy that would no doubt follow after each of of the five very-high carb, refined-food based meals, including such items as bagels, fruit juices, not one but two bananas, chocolate milk, cookies, sports bars and drinks and the cherry on top?  A 12-ounce bag of Swedish Fish.

Sadly, this isn’t an early April fool’s joke.

Do carbs provide energy?


All carbohydrates, whether it’s a regular Coca Cola, Diet Coke or a banana, in all forms which come along with the sweet taste our tongues detect, which then triggers an insulin response (2).

Quick recap: when digested, all carbohydrates are broken down into sugar and absorbed into the bloodstream, leading to an increase in blood sugar levels.

When our blood sugar levels rise, our body releases insulin.

Insulin is a hormone that acts like a key. It allows blood sugar to leave the blood and enter our cells, where it can be used for energy or stored as fat.

Also important to keep in mind that insulin is a fat-sparing hormone. Translation: when the release of insulin is triggered, the body holds fat in reserve for energy.    In other words, we don’t burn fat when we have sugar at our constant disposal.

With rare exception, it behooves most of us to become more efficient at being a fat-burner… whether we are talking about performance on a day to day basis or during a race.

Sourcing more of one’s daily calories from fat provides numerous health benefits including a reduced risk of heart disease, breast cancer and type 2 diabetes (3), a substantial risk reduction for developing dementia versus those with diets favoring carbohydrates for whom the risk for dementia dramatically increased (4), improved mental focus and clarity thanks to steady blood sugar levels, a cleaner burning fuel during athletic feats… and not just those performed at a low heart rate.

With training, the body can begin to perform at a higher work capacity using fat as its fuel at heart rates which it previously would have needed to glean its reserves from sugar.

What’s the down side?

It takes work.

In order for the body to access fat as fuel, gluconeogenesis must occur, a metabolic pathway that results in the generation of glucose from certain non-carbohydrate carbon substrates, including amino acids,  lipids, glycerol and odd-chain fatty acids. (5)

The good news, however, is that our bodies are literally built to do just this; fat is the preferred fuel of human metabolism and has been for most of human evolution. Under normal human circumstances, we actually require only minimal amounts of glucose, most or all of which can be supplied by the liver as needed on a daily basis (6).

So why is this erroneous information continuously spoon fed to us time and time again, for athletic performance, for weight loss, for optimal pregnancy health and virtually every type of eating recommendation?

In his blog, Mark’s Daily Apple, Mark Sisson puts it quite succinctly when he states, “most MDs, the USDA and virtually every RD program in the country can’t seem to grasp why a lower carb approach to eating is a better choice for health and fitness is because their fundamental paradigm, the core theory that underpins everything else in that belief system  is flawed. They remain slaves to the antiquated notion that glucose is the king of fuels, so they live their lives in a fear of running low.” (6)

One might also look at the situation anecdotally; have you personally followed the USDA’s eating guidelines for weight management, for prevention of diabetes, for overall health or athletic performance and if so, how is it working for you?

Given the nearly 70% obesity rate in the US, suffice it to say it’s not working for most.

So what have you got to lose by bucking these silly recommendations and trying something as far-fetched as providing the body the chance to work in its most efficient, most intrinsic manner and letting it use fat as its fuel?

One easy way to start is to shift your percentage of calories away from carb-heavy foods (even something as seemingly benign as too much fruit as well as the obvious bad guys- the “white” foods and corn syrup containing culprits) and slowly begin upping your varied sources of natural fats, while simultaneously eating an abundance of local, in season leafy greens and moderate portions of mindfully sourced proteins.

(Psst… that’s what real food is anyway!)

Unless you’re trying to lose body fat, don’t also reduce your calories to an unfathomably silly low level.    You will notice, however, that with fat as your fuel, you may just end up eating a tad less anyway, thanks to the increased satiety level you’ll find.

Thinking you’re too lean to supply yourself with ample fat as your fuel?

Worry not; even the leanest marathon runner harbors “in excess of 30,000 kilocalories of adipose tissue reserves,” which is “an order of magnitude greater than maximum carbohydrates stores in the body” (7).

Do your research, throw in a bit of common sense and let that be the foundation upon which you decide whether eating three bagels, two bananas, cookies, brownies, chocolate milk and Swedish fish really sounds like a good idea of strategic, intelligent ways to fuel your body to perform a feat such as running a marathon.

(1) Sciolo, R.W. “How to Carb Load for Your Next Race.” Runner’s World, Apr. 2019, pp. 22–23.