Keto for Endurance Athletes – Becoming Keto-Adapted

Keto for Endurance Athletes – Becoming Keto-Adapted

Are you wondering if keto is beneficial for endurance athletes? Comment your thoughts on keto-adapted athlete.

Let’s Define Endurance Exercise

Endurance exercise generally refers to activities that increase aerobic capacity. During aerobic exercise, our oxygen consumption balances with our oxygen production.  This is what I coach, endurance athletes training for anything from a 5k to an Ironman or beyond.

How to Fuel

To power muscle contraction during exercise, you need energy. This energy takes the form of a molecule called adenosine triphosphate, or ATP. All energy comes from ATP. To make ATP, your body uses either fats or carbohydrates.

 How does the body determine what fuel to use?

When you consume carbs prefers to use carbs (glucose) as the source of fuel to make ATP. When carbs are absent, your body shifts to using fat for fuel. A ketogenic diet is one that is low or completely absent of carbs. In this state, the body burns fat for fuel.

 Fat burning unlocks an amazing amount of fuel reserves. Even the leanest athlete has over 40,000 calories stored as fat.

Becoming Keto-Adapted

The process of training the body to prefer burning fat is keto-adaption. Another term for the same process is fat-adaption. The keto-adaption process can take 2 weeks to a couple of months.

Why use the Carbs?

You may be thinking if fat burning is so great, then why do endurance athletes use so many carbs? Keto-adaptation takes time. During this time there is a big dip in performance and a feeling of fatigue.

An athlete who hasn’t become fat adapted can only store around 500 grams of glycogen in the muscle and liver. That is only 2000 calories of energy. If the athlete is not fat adapted, they can not access their fat stores.

These athletes must continue to consume carbohydrates or they will bonk. 2000 calories won’t get you through most triathlons, let alone an Ironman. That’s why many endurance athletes have gu’s and gels taped to their bikes and stuffed in pockets. They need the extra energy.

Keto-adapted athletes, who have put in the time, will have a competitive advantage. They can access a more abundant energy source: Body fat. Body fat contains about 20X the calories as glycogen, even in a lean person.

 Real Keto-Adapted Athletes

 Does keto-adaptation translate to world world results. Athletes from Ultra Marathoner Zach Bitter and the Jumbo-Visma cycling team have found success.

 Emerging research suggesting Keto is compatible with endurance training:

 These studies show there are advantages to being keto-adapted. The biggest complaint about keto is a decline in the upper end of performance. The simple solution is to add back a small amount of carbohydrates during key workouts and on race day. After the training session or race, reverting back to full keto will maintain the fat burning.

Keto For Endurance Athletes: The Bottom Line

If an athlete puts in the time to become keto-adapted, fat is a great fuel for endurance exercise. Once adapted, the almost unlimited fuel from fat. Keto Adaptation plus strategic carbs gives endurance athletes a performance advantage.

Need help becoming keto-adapted?

If you want to become a fat burner but don’t know where to start, check out my services.


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Coach Stephanie

Hi, My name is Coach Stephanie Holbrook. I learned how to regain my health and turn back the clock. I now help endurance athletes show you everything you need to maximize health, performance and a younger feeling body.

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