Nutrition Tip: Using Fat as a Source of Energy

Sports nutrition expert Alexandra Borrelly Lebrun shares her thoughts on how to improve your bodies’ ability to use fat as a source of energy during XTERRA training and racing.

Feb. 15, 2019

By Alexandra Borrelly Lebrun

As a kid, I was led to believe the best way to prepare nutritionally for sports was ‘carbo-loading’, which most of the time meant eating a big plate of pasta with a drizzle of olive oil or tomato sauce. And if you really wanted to liven it up, then a sprinkle of Parmesan cheese was the final ingredient towards athletic success.

This way of thinking stuck with me as I progressed through school and into adulthood. I played sports and exercised most days, so my diet continued to be dominated by carbohydrates whilst ignoring the benefits that fats, vegetables and proteins bring as part of a balanced diet.

Whilst true that we need carbohydrates to contribute to our glycogen stores, we also need to look at the benefits of improving our bodies’ ability to use fat as a source of energy during XTERRA training and racing.

-    Every athlete (even the skinny ones!) have a substantial amount of fat stores ready to convert to energy. 
-    By improving your body’s ability to convert fat, you’ll be able to keep those glycogen stores topped up for longer. In high and very high intensity, only glycogen is used; the good way is to save them for steep and technical uphill, a climb on the bike or a sprint finish on the run.
-    By being less reliant on gels and bars (simple carbohydrates) during the race you’ll keep your stomach happier resulting in fewer GI issues. 

In order to train your body to convert FAT, I recommend a low carb / high fat & protein diet:
•    Make sure to include lots of vegetables for vitamins and minerals.
•    Keep carbohydrates after a race or an intense training to remake the glycogen stores.
•    Replace the amount of carbohydrates, making sure they are made up of wholegrain, low glycemic foods.
•    Take fat and protein meals before a long and slow training like breakfast before a long biking.
•    Increase the amount of quality fats from vegetable oil, avocados, nuts, dark chocolate and oily fish.
•    Aim to eat your animal-based protein (eggs, fatty fish, ship and goat yogurt or cheese) with your breakfast and lunch meals, saving your plant-based protein (Soybeans, Legumes, Quinoa, Hemp Protein) for the evening meals. 

Low carb / high fat & protein breakfast (Example)

2 eggs
A handful of Almond nuts
An avocado
Coffee or Tea 
Avoid sugar, bread, cereals and fruit. 

Note: It may take you a while to get used to training while adjusting to a new diet. You will likely struggle for energy as your body adjusts to having to convert fat rather than carbohydrate so keep the intensity low, less than 70% of your maximum heart rate. You will feel lethargic to begin with and will feel like you have no energy for the first few sessions. After a couple of weeks your body will have adapted, and you will be able to train for longer each time you set out. However, it is important to remember that everyone is different and will respond differently to changes in diet, so make sure you experiment a little to work out what works best for you. 

Alexandra Borrelly Lebrun
Coach for Organicoach
Doctor in Pharmacy specialized in sport nutrition