By Coach Adolfo Salgueiro

In a WhatsApp running group, one of our friends recently shared an article from Men’s Journal Magazine praising the benefits of training in a fasted state. The sub-title alone was promising: The Science-Backed Benefits of Running on Empty, by Spenser Mestel.

I opened it as I thought of how pseudo-science has affected even the most mundane, easy runs lately. Most come from unqualified social media influencers or studies commissioned by companies that will benefit from their results. Dr. Tim Noakes is famous for questioning Gatorade’s science-based recommendations about the benefits of consuming Gatorade. And like that, examples are plenty.

We tend to forget that humans have been running for thousands of years. Hunted gatherers did so for hours while chasing an animal until it collapsed. Yet, they were able to pick it up and take it home to feed their families. They didn’t carry water packs to replenish every drop of sweat. They didn’t carry chews or gels to replace every calorie they burned.

Sure, we have evolved in those thousands of years. The bushmen of the Kalahari were not used to spending their day under air conditioning, sitting in front of a computer, or wearing shoes before they went hunting. But we haven’t entered devolution either. Our bodies were built to withstand a certain level of dehydration and caloric deficit.

I want to leave no room for doubt that I am not advocating against electrolyte replenishment, chews, gels, or any other product. God knows I could not have finished my last few marathons without the help of Maurten gels. What I am advocating against is their overuse, to the point where our bodies become unable to learn how to use their own resources.

Running on an empty stomach is not a fad passed around by social media influencers. Based on the article in question and the study on which it was grounded, it is a well-rounded premise that “fasted cardio” and “low-glycogen” training are similar but distinct practices that can offer real metabolic advantages if done right.

Mestel brings in Professor Richard J. Bloomer, Dean of the College of Health Sciences at the University of Memphis, to clarify the lingo. According to him, a “fasted state” can simply mean not eating for 10–12 hours, like overnight. But low-glycogen training goes further. It implies depleting your muscle glycogen stores, typically by limiting carbs over a longer period. Both approaches can shift your body’s fuel source away from sugar and toward fat, especially during lower-intensity sessions.

According to the study, these are some of the benefits:

• Fat Adaptation: By skipping that pre-run snack or breakfast, your body is nudged into burning fat for fuel. Studies cited in the article showed that both men and women increased fat oxidation after exercising in a fasted state. Simply put, you’re teaching your body to tap into a steadier, more abundant fuel source.

• Less Stomach Drama: Fasted runs can reduce gastric discomfort for those with fussy guts. No food means nothing sloshing around in there. It’s a win for morning runners who’d rather not eat at 5:00 AM just to avoid bonking at 6:00.

• Convenience: This one isn’t science; it’s life. Rolling out of bed, lacing up, and getting it done before breakfast is just easier sometimes.

The science goes even deeper. In a 2010 study from the Journal of Applied Physiology, Beneficial Metabolic Adaptations Due to Endurance Exercise Training in the Fasted State by Van Proeyen et al., this wasn’t anecdotal evidence; it was a tightly controlled experiment. Two groups trained identically on bikes for six weeks. One ate carbs before and during workouts; the other trained fasted.

The result? While both groups got fitter, the fasted group showed superior metabolic adaptations. Their muscles improved at burning fat, their ability to use stored fat (even deep in the muscle) improved, and they kept blood sugar stable over long workouts. The carb-fed group? They didn’t show those perks.

Conclusion

It is not about skipping breakfast forever or starting every workout on an empty stomach. But if you mix in a couple of easy runs each week without eating beforehand, especially when effort is low and stakes are even lower, your body might thank you. You’ll become more metabolically flexible, able to use fat when needed and carbs when it matters most.

Don’t go overboard. It’s about teaching your body to adapt so it can rise to the occasion, whether chasing a PR or just running for joy.

You can read the Men’s Journal article by clicking here.

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