Fueling for Performance

17 May, 2021

What is a Low Carbohydrate, High Fat (LCHF) diet?

Also known as a ketogenic diet, a LCHF diet is high in fat (typically about 70 - 85% of calories from fat), moderate in protein (15 - 20% of calories from protein), and less than 50 grams of carbohydrates per day. 

I’ve been doing high-intensity interval training (HIIT) classes for the past year and have recently switched to a LCHF diet. At first, I felt great, but now the workouts are getting harder, and I’m not able to do what I was doing before. Is this related to the change in my diet or something else?

HIIT workouts are popular because they incorporate anaerobic exercise with less-intense recovery periods. Some examples of anaerobic exercise include sprinting, heavy weight lifting, and sports, such as gymnastics. Anaerobic activities rely primarily on carbohydrates for energy. Therefore, the LCHF diet may decrease the intensity you can sustain during the practice. 

Since carbohydrates are the primary source of energy used during this type of exercise, a LCHF diet is not recommended

I usually eat a hard-boiled egg and a handful of nuts before my HIIT workout. Should I add a slice of whole-grain toast?

While eggs and nuts are full of nutrition and good energy, they are not ideal as a pre-workout snack or meal. In fact, you should stay away from fiber, fat, and protein before you participate in anaerobic workouts. 

Fiber, protein, and fat take longer for your body to digest. Therefore, your body will not have quick access to the fuel needed for high-intensity performance. You may also experience digestive distress because these foods are not easy for your body to break down. Adding a little fat and protein pre-workout is OK, but keep it minimal. 

What about my long runs? They are anywhere from 60 - 120 minutes. However, they are not as intense as HIIT workouts. I’ve heard a LCHF diet could help me from “hitting the wall.” Is this true?

Activities such as running, cycling, brisk walking, and cross country skiing are known as aerobic exercise. Aerobic exercise is generally light-to-moderate in intensity and is performed for extended periods. This type of training relies on carbohydrates and fat for energy, and it needs both sources for optimal performance. 

A LCHF diet will most likely decrease the intensity and duration you can sustain during these activities. 

Suppose you are interested in exploring more about LCHF eating? There are phases of training in which it might be beneficial. Check out this month’s mini-article for more information about a LCHF diet to discover if it is right for you!  

Athletes’ Do’s and Don'ts for Following a LCHF Diet:

  • Avoid LCHF diet during the competition phase. 
  • Carbohydrates are crucial for optimal performance and are, therefore, essential to eat during training sessions to know how to fuel for the event. Introducing new foods during competition increases the chances of gastrointestinal distress
  • LCHF diets are not ideal for athletes competing at high-intensity exercises. 
  • A sport registered dietitian nutritionist (RDN) can help individualize your fueling needs based on the type, intensity, and duration of exercise.

To learn more ways to enhance the human condition through medical nutrition therapy and primary prevention please contact Disease Management and Prevention Dietitians PLLC.

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