Why intermittent fasting and running do not mix

When running became mainstream, around 2020, it pulled popular fitness trends into its orbit. Some, like yoga or creatine supplements, seem to be compatible with it and are not dangerous. Then, there is intermittent fasting: the long, dubious darling of the biohacking world.

For the uninitiated, intermittent fasting consists of restricting caloric intake for several hours in an effort to lose weight, regulate blood glucose and control cholesterol. The actual effectiveness of this method is debated in the literature, but health influencers like Brian Johnson – who often eats the majority of his day’s calories by 10 am – famously apply it in their routine.

In recent years, the world of recreational running has become interested in the potential benefits of running while hungry. Scientists are studying the intersection of fasting and fasting, the media is running to report the trend, and the Reddit thread on its interplay continues to stretch. If you follow running influencers on social media, they may tell you that restricting your caloric intake will make you a better runner.

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But is it really true? Some early theories seem convincing. What is popular is that sometimes exercising in a fasted state can encourage your body to rely on fat as fuel. For easy, low intensity running, it can feel good and can help some runners become more comfortable relying on things other than carbs for energy.

Then, there is the question of intermittent fasting as a control of binging: where limiting late night snacking can lead to better sleep and overall eating habits. There’s also something to be said about developing an eating routine that relieves one of the digestive and digestive problems along the way.

It all sounds promising; and yet, my 15 years as a competitive distance runner, I have not been encouraged intermittently fast by a single coach, teammate or rival. Any seasoned runner will tell you: This is just not something we do.

There’s a reason for that: Reaching that potential, marginal benefit is like grabbing a $5 bill while standing on the edge of a cliff. There is far more to lose than to win.

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Ignoring hunger signals and letting the clock decide when you should eat while training as a runner exposes you to short-, medium- and long-term pitfalls. Immediately, you risk sabotaging your daily training. Speed ​​sessions, long runs, and even easy runs require glycogen. When there is a lack of supply, it becomes more difficult to hit the pace, finish the run feeling strong, and adapt to the training. Hitting the wall is so much easier. Then, not eating then delays the intake of protein and carbohydrates, reduces muscle repair, and even compromises immune function.

Even if you don’t feel bonk right away, you’re setting yourself up for the week ahead if you don’t eat. Long-distance running is already a tremendous physiological stress. Add caloric restriction and you increase the risk of poor recovery, hormonal disorders, mood dips and injuries. There is no diet in the world that can compensate for the huge loss of fitness brought on by months on the sidelines.

Beyond that, restricted eating can expose a long-term problem. Relative Energy Deficiency in Sport (RED-S), where the body falls into a chronic pattern of low energy availability, is a real problem in endurance athletes. It can lead to decreased performance, lower bone density, and hormonal imbalances that are difficult to shake.

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There are other ways to gain benefits without cutting food. Add an extra run to your weekly plan, introduce more intensity to your exercise routine, lift weights regularly, or even train yourself to go to bed at the same time every night. Distance running rewards basic boring.

I wish I had cookie cutter advice for how to eat on the go. There are general recommendations (simple carbs like cereal or a banana in the hour before the run, protein and lots of carbs after the fact), but the specifics come down to a personal level. So, trial and error is your friend: Play with the time and type of food, and notice how different approaches make you run away, and also the next day.

And when you do that, remember that, on the run, you’ll be fighting more terrifying monsters when you’re running low on fuel than when you’re overfuelling. So when you are hungry, eat.