In a WhatsApp running group, one of our friends recently shared an article from Menâs 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 Gatoradeâs science-based recommendations about the benefits of consuming Gatorade. And like that, examples are plenty.
Running on empty has its scientifically proven benefits (Image by ChatGPT)
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 didnât carry water packs to replenish every drop of sweat. They didnât 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 havenât 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 âfasted cardioâ and âlow-glycogenâ training are similar but distinct practices that can offer real metabolic advantages if done right.
While skipping breakfast can be beneficial, you don’t have to do it for every run (Photo Pexels)
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 âfasted stateâ can simply mean not eating for 10â12 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 bodyâs 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, youâre 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. Itâs a win for morning runners whoâd rather not eat at 5:00 AM just to avoid bonking at 6:00.
Convenience: This one isnât science; itâs 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 wasnât 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 didnât 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. Youâll become more metabolically flexible, able to use fat when needed and carbs when it matters most.
Donât go overboard. Itâs about teaching your body to adapt so it can rise to the occasion, whether chasing a PR or just running for joy.
Curious to try it? Leave a comment and let me know your experience. And donât forget to subscribe to the Foultips.Run newsletter by clicking the button below.
 When I started running marathons in the early-1980s, back when dinosaurs roamed the earth, guzzling carbs indiscriminately was the way of life. The more carbs you ate, the more energy you would have stored for your long run the next day. It didnât matter if they came from a pizza, your sixth bowl of pasta or a handful of cookies. The point was to ingest in as much as you could.
Regardless of how much pasta you eat the night before, your body canât store beyond its capabilities (Photo by Anna Tis, from Pexels)
The thought process was that if carbs were good for endurance, more carbs would be better. And many, many more carbs would the way better. I recently heard an interview with Dr. Tim Noakes, the influential South African sports scientist and author of several books on exercise and diet, where he regretted his role in the popularization of the carbo-loading myth. He said that if you had an earlier edition of his groundbreaking book The Lore of Running, published in 1985, you should rip off the entire chapter on nutrition, where he champs this topic. He now preaches a low carb, high fat diet.
Now that there is money to be made, running has gone through tons of research in the last couple of decades. Nutrition is one of the subjects with most studies and scientific papers. Therefore hydration and gel options have grown exponentially in the last few years. Same with pre and post-workout powders and supplements. None of this was available way-back-when. We still call âwater stationsâ by this name because when they started, that is all they offered. Gatorade came later. Earlier runs didnât even have water. But I digress.
The science on glycogen is a bit complex to get into it in this post, plus, this is not a peer-reviewed paper for publication. There are plenty of resources available to explain what glycogen is and how it is metabolized to produce the energy that will push you forward. What is important to know is the new, science-based approach, about how to practice the proverbial carbo-loading.
Most runners are well familiarized with the term glycogen, the most immediate source of energy while we run. Anecdotally, I must have heard that word for the first time about 15 years ago, even though glycogen was discovered in 1857, four years before Abraham Lincoln became President.
In the early eighties there was this theory that if you depleted your body from carbohydrates the week of the marathon and about 3 days prior you started consuming carbs indiscriminately, your body would absorb more and thus have a bigger reserve. Despite the fact this silly theory has been disproven, it is still practiced by some marathoners today, to atrocious results. The amount your body can store is finite. So, regardless of how much pasta you swallow the night before, you wonât be able to collect more than what your bodyâs capacity allows.
Carbs are very important for a runner, thus the carbo-load. We do so to restore the glycogen stores in our muscles and liver. Just by being alive, our body burns through its glycogen. They deplete faster with activity. We need to replenish them to provide our body with quick fuel to burn during our runs. You could train your body to burn fat instead of glycogen as its primary source of fuel but that is beyond the scope of this post.
It is not just about carbs. They have to be the right carbs (Photo by Dana Tentis, from Pexels)
Assuming you are well hydrated, appropriately fed and in good health, your body has all the resources it may need to run from a 5K to a half marathon. Thereâs no need to overthink those aspects of your race unless it is an extremely hot or humid (or both) day. Beyond that, each mile is pushing your body closer to its reserve limits. And when the reserves get depleted, you hit the no-longer-so-mythical wall. Therefore, for longer races a hydration and fueling strategy is imperative.
Now, the other important point to consider is that not all carbs are created equal. Stuffing yourself with Oreos, Doritos and donuts is not carbo-loading. Those are simple carbohydrates that are broken down immediately and enter the bloodstream as sugars. They do not get stored for later use in your muscles or liver, thus, contributing nothing to what you should be trying to accomplish. This is the reason most sports drinks and gels are packed with sugars and simple carbs. So they can be tapped immediately by your system to produce energy. You wouldnât carbo load with those.
What youâd rather be doing is consuming complex carbohydrates, such as brown rice, quinoa, oats, sweet potatoes, vegetables, and whole grain pastas. They take longer to break down and get stored in your muscles so they can be used later, like when you are running/racing. All this works better if you prepare your system, so these products become a compliment to your body resources and not the only source of energy production for long distance running.
Time has come to change our view on the old science. Time has come to adopt what the new research has shown to work. Letâs move forward, then.
As runners who always want to perform at our best, it is normal to have more fun running at race pace than going through all the peripheral stuff that gets us there. Stretching, cooldown, mobility drills, reps, days off and very often, warming up properly. Unfortunately, many runners see the warmup not as an element that to enhance your workout, but a waste your time or something to screw your average pace.
Reasons to skip your warmup abound. You may want to keep up with the buddy that runs faster than you, or you may be afraid of what your friends will say when they see you in Strava. Maybe youâre on a rush to get to that runnerâs high. Whatever your reason is, you are not helping yourself in becoming neither a better athlete nor a healthier runner.
Ethiopian runners go out of their way to force themselves to run super slow while warming up.
In the book âOut of Thin Airâ, anthropologist Michael Crawley, went to Ethiopia to learn about its running culture. He explains how locals start running painfully slow. They go to the forest to warm up zigzagging around trees, assuring that pace canât be picked up; and in a single file, to guarantee that nobody will be surging ahead of time.
You donât have to be an Ethiopian, Kenyan, or Ugandan to apply the slow warmup concept. Western elite runners apply it all the time. In his book âRun for Your Lifeâ, Dr. Mark Cucuzzella, tells how he sometimes runs 13, or 14-minute miles and still feel happy to be out there running. This is a guy who has won marathons, and into his 50s, can still run sub-3.
The Purpose and Value of Warming Up
Steve Magness, former coach at the University of Houston (in my opinion one of the most knowledgeable coaches on the scientific side of our sport), reassures that the warmup sets up your run. It helps you get the body revved up and prepared for whatever we want it to accomplish with it.
âPhysiologically -he explains- we get our core temperature, body temperature and muscle temperature up a little bit. We get our metabolism going, we get our VO2 up, and we are priming the bodyâs systems. If I didnât do a warmup and just went out the door and start running as hard as I can, my energetic system wouldnât be ramped up and ready to go. Then, my body will try to cover all the energetic demands with the anaerobic system before the aerobic system is ready.â
Coach Steve Magness explains the physiological and psychological benefits of warming up properly.
âFrom a physiological side, you are priming your motor system so when it comes time to flip the switch to work hard, your body can recruit the muscle fibers to do the jobâ, assures Magness.
You donât have to be a rocket scientist or a doctor to understand the multiple benefits of what was said in the last two paragraphs. The more you work on your warmup and the more you make it part of your daily routine, the more you will realize its benefits during the hard part of your workouts. And soon enough, without noticing, it will become part of your ritual.
âThe warmup also gets you in the best psychological state -continues Magness- so you can see your training or your race as a challenge instead of a threat. Something you can take on instead of confronting. It can give you a semblance of control in a situation where you often lack it.â
Keys to the Warmup
The warmup is a personal aspect of your training. You need to find out what it works for you, not what works for your friend or for Eliud Kipchoge.
When we talk about warming up it is not exclusively about running. Dynamic stretching and mobility drills should be part of it, too. This includes easy lunges, hip and ankles rotations, etc. Remember that arms are a key element of your running, so include range of motion of arms, and arm swings as part of your ritual.
The key to the warmup, I insist, is to go slow. Very slow. You canât be worried on what that it will do to your Strava averages. But, if you canât control yourself and you must brag to your friends, stop the watch after warmup and then start another session with the work portion of your workout. This should suit your ego just fine.
How long should you warm up? You donât want to be burning more glycogen than necessary. For a long-distance runner (5k and over), 10 to 15 minutes is usually sufficient.
âGlycogen is a limited resource in the muscle tissue and organs â explains Jonathan Marcus, Head Coach at High Performance West- so, if you start warming up too fast, the body has to cover the gap burning a high-efficient energy source that you should be using during your hard workout, or race, before you even get started. This is why the warmup needs to be taken super slow.âÂ
If you are not warming up properly, today is the perfect time to adjust, make it part of your ritual and start reaping its benefits.
