What is the Impact of the Keto Diet and Long-Distance Running?
Chances are, you’ve heard someone in your run club talk about the ketogenic diet. It’s being buzzed about right now thanks to that it’s an effective way to lose weight. Should long-distance runners try it? We tapped top experts to help set the record straight for you.
The Keto Diet
Unlike low-carb, high-fat diets, the ketogenic diet (or keto diet) sets guidelines on how to break down your macronutrient carbohydrates, protein, and fat intake.
Those that follow a keto diet consume 75-80 percent of their calories from fat and almost zero to five percent from carbs. The fuel source your body and brain prefer to tap first. Staples of this diet include fish, meat, eggs, dairy, oils, and some green veggies. Even healthy, complex carbs like whole-wheat pasta, rice, potatoes, and fruit are off-limits.
Here’s how the keto diet works
When your body no longer has access to fuel from carbohydrates either because they’ve been cut from your diet or you haven’t eaten in a long time it goes into a state called ketosis.
That means, your body looks for the next best fuel source of energy: fat. And it uses the available fatty acids to produce a compound called ketones, which is why people who are in ketosis and eating more fat will start to burn more fat.
While our bodies first burn carbohydrates, ketones can actually fuel the brain and body, says Lizzie Kasparek, R.D., a sports dietitian with the Sanford Sports Science Institute. So it’s not like you’re depleting your body in any way.
“Being in ketosis does not imply reduced muscle glycogen levels. Over time, the keto-adapted athlete improves his or her ability to burn fat for fuel and still have glycogen available,” says Kenneth Ford, Ph.D., director, and CEO of the Institute for Human and Machine Cognition.
The Science Behind Ketogenic Diet
But whether runners, specifically, should put their bodies in a state of ketosis depends on your goals. One study of five endurance athletes showed that a 10-week keto diet improved the athletes’ body composition and well-being but not their performance.
In fact, the athletes initially experienced reduced energy levels and an inability to undertake high-intensity bouts of exercise. But this study was small, and experts acknowledge more research is needed to study keto’s full effects.
“There isn’t really a lot of good research that shows those people can perform better, and that’s really what runners care about,” Kasparek says.
One reason performance may not be affected, she suggests, is due to ketone measurement. Diabetics have to routinely measure their ketones; if levels are too high, it can indicate a major complication of diabetes. But many people who casually try a keto diet don’t measure ketones, so they may not actually be in a state of ketosis.
your body wants to start tapping into fat stores
Ford also points out that in the studies examining at ketosis and performance with negative results, the athletes are not often sufficiently fat-adapted (when the body is trained to tap fat stores for energy, which can take several months) or even in ketosis, making it hard to truly gauge whether the diet is effective when it comes to performance.
Runners who may benefit from fat adaptation are those who are running, long distances, like ultrarunners. Once you hit those later miles (30, 40, and beyond), your body wants to start tapping into fat stores.
So if you’ve done any sort of fat-adapted training—not eating before a morning run, not fueling during an 18-miler—your body can better adjust, Kasparek, says.
For everyone else, carbs are still probably your best bet, especially if you’re running at higher intensities than you would be when running 50 miles at a 15-minute pace.
"When you’re running at a lower intensity, you need to burn more fat as fuel,” Kasparek explains. “But because carbs are the main source of fuel at higher intensities, you may be sacrificing key workouts or your race to follow a certain diet.”
Here is another interesting blog about keto and training: Keto and swimming.
Which brings us back to the main question: Should you try the keto diet? Yes! The bottom line is: If done right, runners who need to be able to tap into fat stores over long distances benefit from the Keto diet.
A keto diet can be really simple, but it helps to learn some basic skills.
These tips and guides will help you answer all the common keto questions.
Click here for An Easy Detailed Guide to Follow for Beginners to The Keto Diet.