You get up in the morning, put on your shoes and go for a run. Therefore, before work, at eight in the morning, you are in a calorie deficit. Logically speaking, this must be a good way to lose weight. And since almost all of us are trying to lose weight, that’s probably why “running on an empty stomach” is often searched for in Internet browsers. But is training on an empty stomach really a good idea?
Amateur runner
Of course, almost all of us want the same thing – to lose weight effortlessly/easily/quickly/expressly (delete as appropriate). But we all know perfectly well that there is no such method. I won’t dwell on the research that says fasted running burns fat and helps you lose weight, or on the research that says just the opposite. Because we cannot lump people together and establish clearly that by running without breakfast, each of us can lose 2 kg more in two weeks than if we ate breakfast. Breakfast can’t be put into one bag either – for some it will be oatmeal with water, for others it will be three eggs with half a jar of mayonnaise. And more importantly, runners cannot be lumped together either.
Because let’s face it, running is not the same. If you only go for a 30-minute jog some mornings and that’s it, then the truth is, the issue of running on an empty stomach does not concern you at all. And it will not be decisive for your weight loss, because, as you know, the most important thing is whether you end the day with a caloric deficit or whether you will reward yourself immediately after training in the form of meringue with whipped cream and coffee with caramel. You have to consider the sense of such an action yourself – whether to burn 300 calories by jogging without breakfast and then eat 1000 calories hungry as a wolf, or maybe it is better to eat a light breakfast (200 calories), have the strength to run longer and burn more calories (e.g. 600) ?
Runner training
However, if you are a training runner, fasted running may be for you a completely different meaning than losing weight.
Under normal conditions, there are approximately 700 calories of stored glucose in the liver. It is enough for about 1.5-2 hours of running at moderate intensity, but without exercise it takes from 10 to 12 hours to use the energy reserves stored in the liver. After depleting glucose, runners obviously hit a “wall”, which is the fear of every marathon runner approaching 30 kilometers. However, a “wall” does not mean that the body no longer has the energy to continue the effort, only that switches to energy sources other than carbohydrates. That is, for fats.
The body uses them when there is a lack of carbohydrates, and this is what happens when we go for a run in the morning without breakfast. That’s why some research shows that training on an empty stomach can influence the ability to sensibly manage carbohydrates and use fat tissue as fuel. This does not necessarily mean that we burn more fat when running on an empty stomach, but only that the body learns to cope with certain deficiencies and the “wall” is no longer dangerous.
Only for ultras
Of course, this process of obtaining energy from sources other than carbohydrates takes longer and the energy obtained in this way is delivered slower, so it is completely useless when running fast. But definitely makes sense for long-distance runners. Marathons and ultra runs are low-intensity runs where the ability to exercise for a long time is crucial, and this in turn is possible when the body can continue the effort even though carbohydrate stores are depleted. In runners’ terms, when you hit a wall, your body is trained to deal with it. Therefore, in training for marathons and ultra runs, fasted running may bring certain benefits.
However, it is worth realizing that One swallow does not make spring. You can probably treat yourself to a one-time fasted run two weeks before the marathon. Adapting the body to use fats as an energy source is a process that requires training for several or even several months.
So what should such training look like and how often should you do it? The most important thing is that it is light training intended for slow, regenerative running up to 60 or maximum 90 minutes. Fat oxidation dominates only during low-intensity exercise (<45% VO2max), at higher exercise intensity (>65% VO2max) carbohydrate oxidation dominates. Therefore, these cannot be heavy accents or strong training sessions, because you will certainly not perform this training correctly and with the appropriate quality, nor will you adapt your body to use energy sources other than carbohydrates. Fasted training can be performed once or at most twice a week, it should only complement the training plan as an additional element, but certainly not complete it.
Intermittent Fasting
Interestingly, fasted running is such a popular method abroad that ultrarunners not only train before breakfast, who fast on purpose, to teach the body to use energy obtained from sources other than carbohydrates. This new running trend (as well as one of the most popular diets in 2020) is called “Intermittent Fasting” (IF, intermittent fasting) and depending on what it is, it can be used in different ways:
- fasting lasting a full 24 hours, used two or three times a week (so-called ICR – Intermittent Calorie Restriction), the so-called 5/2, i.e. a regular diet for 5 days and 2 days of fasting, or 4/3. It may also involve limiting calories on fasting days to 25%-30% of the daily requirement;
- fasting for 24 hours or calorie restriction for 24 hours, but every other day, alternating with the day of the regular diet (ADF – Alternate Day Fasting, or eat-stop-eat);
- fasting for a certain number of hours a day (so-called TRF – Time Restricted Feeding). The most popular method is the so-called 16/8, i.e. fasting for 16 hours and you can eat for 8 hours. You choose what hours you fast, so most often it is at night, and of course it is best to train immediately after the end of the fast. There are also other varieties, e.g. 18/6, 20/4, etc.
Zero calories
What are the effects of using the intermittent fasting method? Let’s use this as an example Michael McKnight, known on instagram as “the low carb runner”, who used the Intermittent Fasting method in the 18/6 variant in his training. Michael ran 100 miles on May 8, 2020, taking part in the race zero calories. He repeated his feat in December 2021, this time running for 24 hours, during which he managed to run 118 miles (190 km) also taking in zero calories. Despite this, he felt so good that at the end of the run he had the strength to accelerate, and he covered the last mile at a pace of 4’06″/km.
Is this method good for everyone? As I pointed out at the beginning, you cannot lump all runners into one bag, so it cannot be said with certainty that both fasted running and Intermittent Fasting will bring the same benefits to everyone. As Michael McKnight summed it up perfectly: “We are all built differently and each of us has a completely different approach to nutrition“. But although there is no one ideal method, we should at least try to find it for ourselves. Who knows, maybe fasted training or intermittent fasting will also allow you to reach a higher level of running?
Sources
https://www.instagram.com/p/CYKJhhVJvO8/
http://warszawskibiegacz.pl/bieganie-na-czczo-za-i-przeciw/
https://www.adriannapalka.pl/bieganie-na-czczo-czy-po-posilku/
https://www.fabrykasily.pl/bieganie/bieganie-na-czczo
https://upacjenta.pl/poradnik/bieganie-na-czczo-lub-po-posilku-co-wybrac-i-dlaczego
https://www.jamesrunsfar.com/blog/intermittent-fasting-for-ultra-runners
https://www.elo.health/articles/intermittent-fasting-for-runners/
https://www.runtothefinish.com/intermittent-fasting-weight-loss/
https://www.dovepress.com/exercise-training-and-fasting-current-insights-peer-reviewed-fulltext-article-OAJSM
https://www.instagram.com/p/CYKJhhVJvO8/
https://holdthecarbs.ca/blogs/tom-ando-team-holdthecarbs/interview-with-low-carb-keto-ultrarunner-michael-mcknight
https://kogalla.com/blogs/news/michael-mcknight-runs-100-miles-on-zero-calories?page=3