How To Use The Ketogenic Diet for Physical Performance

Should those who are physically active continue eating low-carb? It’s a fair question for those wanting to follow a ketogenic diet for better health, and that’s why we’ll be exploring the main areas of ketosis for physical performance.

The ketogenic diet and ketosis have been used traditionally by physicians and other professionals for a few different medical reasons, including improving the health of those with diabetes and treating neurological disorders like epilepsy.

But now, we’ve begun to explore other factors where the ketogenic diet can have a positive effect, including mental focus, weight loss, and in this article, ketosis for physical performance.

The Ketogenic Diet for Exercise

While the emphasis for exercise is usually on high carbohydrate intake, the ketogenic diet takes a low-carb approach to energy. Those on a ketogenic diet generally stay within a range of 30-50 grams of carbs per day, and a large amount of food in the diet comes from fat.

The ketogenic diet involves a dietary breakdown of:

  • Low carbohydrate intake
  • Moderate protein intake
  • High fat intake

The low intake of carbs is meant to put the dieter into ketosis, where the body creates ketones from fat stores to use as the main energy source, instead of carbs, for the body and even partly for the brain. Molecules known as ketones are produced during the process.

This means that someone exercising while eating a ketogenic diet is going to be using primarily fat as fuel for their physical activity.

Misconceptions About Ketosis for Physical Performance

A long-held belief among the nutrition and medical community is that carbohydrates must make up a high portion of your diet in order to maintain physical performance at an ideal level. This belief mostly stems from studies in the last 100 years looking at muscle glycogen and its link to high intensity exercise.

However, there are a few reasons to question this thought process:

  • We’ve observed cultures that didn’t eat in line with the carb-heavy philosophy, such as the Inuit people in the Canadian and Alaskan Arctic regions. Before their diets changed a lot, scientists were able to observe their traditional diet and see that it contained virtually no known carbohydrates, yet they were able to function normally physically.
  • Demographic evidence of past European cultures has shown them living as primarily hunters without any noted physical impediments.
  • While diets with more carbohydrates may prove better for higher-intensity, short-term forms of exercise, the limitations of the ketogenic diet for physical performance have been over exaggerated. In fact, ketosis can have a healthy role in relation physical activity for most individuals.

Let’s take a look at the differences associated with using ketones for fuel versus using carbs for fuel.

Fat Adaptation in Ketosis

With a ketogenic or other low carb diet, the body experiences fat adaptation, or keto-adaption, where it becomes more efficient at burning fat and ketones for fuel. This adaptation can be strong and have a great impact on the fat burning process during exercise.

During a recent study, ultra-endurance athletes who were on a ketogenic diet for an average of 20 months were shown to burn up to 2.3 times more fat than the high-carb group during a three-hour run. The study also found that muscle glycogen use and repletion during and after the exercise was similar between the low-carb and high-carb groups. This is a significant demonstration of the power of keto-adaptation for exercise.

Endurance Exercise and Ketosis

As we’ve established, fat can be used for energy when carbs aren’t available for use. While carbs do provide more fuel for the body to perform at higher intensities, fat is what provides more energy during exercise at lower intensities.

However, this might be open to question as well. In one study, researchers recorded athletes following a ketogenic diet had burned mostly fat during exercise at up to 70% of their max intensity, while the high-carb athletes burned fat at 55%. This again demonstrates the increased effectiveness of ketosis for fuel during exercise when a person’s body has adapted to burning primarily fat for energy.

With this in mind, it’s still important to recognize that some elite athletes may require energy more quickly than the rate at which they can get it from fat, and more research is needed on the subject to know the details for sure. That being said, a low-carb ketogenic diet can be helpful in regards to exercise for:

  • Preventing tiredness when doing longer exercise
  • Perform low-to-moderate intensity levels of exercise through keto-adaptation
  • Improving health and losing more fat through regular exercise and low-carb eating
  • Maintaining blood glucose during exercise
  • Adapting the body to burning more fat, which might be able to help the body preserve glycogen in the muscles during exercise

Muscle Growth and Ketosis

We don’t currently have research showing a specific benefit of ketogenic diets over higher carb diets for muscle growth during strength or high-intensity exercises. That being said, there are some studies show that in addition to using more fat as fuel, low-carb diets can also help preserve muscle glycogen for some athletes. Plus, a ketogenic diet has the advantage of teaching the body to more easily turn to fat burning for fuel.

However, that doesn’t mean it’s necessary to turn to a very high carb diet to see success in muscle growth and performance. In fact, a diet that is higher in protein and more moderate in carb intake might be the best for achieving ideal body composition and muscle growth for most active people and some sports athletes.

An Early Account of Ketogenic Diet Performance

Let’s take a second to travel back over a hundred years ago to one of the earliest recorded examples of a ketogenic diet for intense physical performance.

The evidence was shown in a written diary published in the New York Herald in the Fall of 1880. The diary belonged to Lt. Frederick Schwatka, a West Point and Bellevue Hospital Medical College graduate and leader of an expedition between 1878 to 1880 to look for the lost Royal Navy Franklin expedition [1].

The group consisted of 18 people made up of three Inuit families, four Caucasians, and three dog sleds with 44 dogs. They began on the west coast of Hudson’s Bay with a month’s supply of food that was mostly walrus blubber (fat). Once that was gone, they had to subsist only on food from hunting and fishing (animals foods full of protein and fats). The journey on foot spanned 3,000 miles through snow, ice, and tundra.

By May of 1880, the whole team and their dogs returned safely to the Bay! This older account is a great example of the human ability to perform exceptional physical feats on very low, if any, amounts of carbs.

Benefits of Ketosis for Athletes

A lower carb intake does have some potential benefits for certain types of athletes. For example:

  • Some research shows that the preservation of glycogen stores from a ketogenic diet can prevent endurance athletes from “hitting the wall” while performing endurance exercises.
  • Keto-adaptation can lead to less reliance on carbs during endurance exercise, which can help athletes during events where there is limited access to food or those who can’t easily digest carbs during exercise.
  • A diet that promotes more fat loss is important for improve the ratio of fat to muscle, which is crucial for those looking to improve their exercise performance or meet certain weight goals for their sport, such as in wrestling, weightlifting, and boxing.
  • The practice of exercising while glycogen stores are low is a training technique popular for improving the function of mitochondria, enzymes, and fat usage to improve overall health and physical performance long-term.
  • Eating a ketogenic diet might also be a good diet practice for an athlete’s off season as they maintain their health while resting.

While the jury is still out on the benefits of a ketogenic diet over a higher carb diet for all athletes, ketosis for physical performance can be helpful for those doing ultra-endurance or low-intensity exercise meant to maintain health.

And let’s not forget the immense health benefits of eating a ketogenic diet, which just about every aspect of our lives overall, including physical performance.


  1. Stackpole EA, ed: The long arctic search: the narrative of lieutenant Frederick Schwatka. Mystic CT. The Marine Historical Society. 1965

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