Mastering Carb Loading: Fueling Your Endurance Event for Peak Performance

When it comes to preparing for endurance events, whether that is a marathon, an ultra-marathon, or a triathlon, carbohydrates are of utmost importance. In fact, carbohydrates, commonly known as carbs, serve as the main energy source for the brain and nervous system, and are also the body’s favored fuel during prolonged physical activity.

The Science Behind a Carb Load

 

When we eat carbohydrates, our bodies turn them into glucose, which is used for energy. If we don’t use all the glucose right away, our bodies can save the extra in our muscles and liver as glycogen. This glycogen is like a backup energy source that kicks in when our blood sugar drops. If we run out of glucose and glycogen, our bodies will switch to burning fat for energy, but this process is slower and harder on the body. If you’ve ever “hit a wall” during a long run or endurance event, it’s likely because your body ran out of glucose, and you did not have enough carbs stored to give you immediate energy. Eating more carbohydrates than usual in the days leading up to a big event will help build up extra fuel to keep you going longer during the event. This carbohydrate surplus is referred to as carb loading. 

Here’s a guide on how to effectively carb load to ensure you are ready to perform at your best on race day.

Recipe to Carb Loading

Carb loading typically begins 1-3 days before the event, “the event” being an upcoming endurance race that you have planned. Starting later will simply mean that you will have to fit a larger amount of carbs in a shorter time frame, but the results will be similar in the end. In other words, the amount of carbohydrates you need to consume depends on the duration of your carb loading phase:

  • If you are carb loading for 2.5-3 days, you will need to consume 7-8 grams of carbs per kg of body weight each day.
  • If you are carb loading for 1-2 days, you will need to consume 10-12 grams of carbs per kg of body weight each day. 

For instance, if John, an endurance athlete, weighs 75 kg (165 lbs), he would need to consume 525-600 g (7-8 g/kg) of carbs every day for 2.5 to 3 days, which is equivalent to about 60-70% of his daily intake just in carbs.

Planning your Carb Load

 

In theory, any type of carbohydrate could work for your carb load. However, some types are easier to digest and obtain energy from than others. Favorable options can include the following:

  • Grains: white rice, bread, pasta
  • Starchy vegetables: potato, sweet potatoes
  • Fruits
  • Dairy products: yogurt, milk 
  • Beverages: juice, Gatorade (with sugar)
  • Snacks: gels, chews, candy, baked goods, cookies

Of note: be mindful of fiber content. Typically, runners want to opt for nourishing options in their diet, but counter intuitively, it would be encouraged to reach for lower fiber, more easily digested carbohydrates during your carb load for the sake of being able to consume such a large volume. For example, eating a large amount of oats may provide a significant amount of carbohydrate, but the volume and fiber content may make you feel very full for a long period of time. This will impact your capacity to eat shortly after and result in an inability to consume an appropriate amount of carbs for the load. 

One trick that can be helpful if you are worried about constipation and bloating is to incorporate a minimum of 4 medjool dates in your carb loading days as these dried fruits are high in fiber and also very high in sugar. 

For easier planning, you can break up your carbohydrates into increments of approximately 50 g and calculate the number of portions needed. Here are examples of what 50 g of carbs may look like:

  • 3 medjool dates 
  • 1 medium bagel
  • 1 large banana
  • 1 cup of cooked pasta
  • 1 medium baked potato or sweet potato
  • 2 slices of bread
  • 1 ÂĽ cups of cooked oatmeal
  • ÂĽ cup of granola
  • 2 medium apples or oranges
  • 1 ½ cup of cooked rice
  • 3 medium carrots
  • 2/3 cups of raisins 

Let’s get back to John as an example. Remember that John is aiming to consume -600g of carbs for 3 days prior to his race.  This means that he would need to eat 12 servings of 50g of carbs per day. A sample menu for John could look like this:

  • Breakfast: 1 medium bagel with butter (~50 g), 1 large banana (~50 g), and 1 cup of orange juice (~25 g)
  • AM snack: 3 medjool dates (~50 g), 1 apple (~25 g), and 1 Gatorade (~25 g)
  • Lunch: sandwich of choice (~50 g for 2 slices of bread), 3 medium carrots (~50 g), and 1 cup of applesauce (~50 g)
  • PM snack: pretzels (~50 g for 35 pretzels) and 2 oranges (~50 g)
  • Dinner: 1 cup of cooked pasta with sauce of choice (~50 g), and 4 Oreo cookies (~50 g)
  • Evening snack: 250 ml of chocolate milk (~25 g)

John’s total for the day: 600 g of carbs (10 portions of ~50 g and 4 portions of ~25 g)

Key Elements to Remember

  • During your carb load, opt for easily digestible carbs rather than what you would typically eat.
  • Try to limit fat, fiber and protein intake as this may make consuming an adequate amount of carbs difficult.
  • Consuming  carbs in the form of liquid may make achieving your target more feasible.
  • Try to keep your breakfast on race day similar to a breakfast that you’re used to consuming in order to ensure that you don’t experience any digestive upset during the race. 
  • If carb loading feels uncomfortable, that means you’re doing it right!

Conclusion

Remember, carb loading doesn’t mean that you must eat excessively, but rather eat differently than the way you typically do. Focus on prioritizing carbohydrates over proteins, fats, and fruits/vegetables. Additionally, ensure you’re adequately fueling not only before, but also during the race to maintain optimal glucose levels. Finally, if you feel that you need help with your carb loading, consider booking an appointment with one of our dietitians. They’ll help you create a personalized plan to ensure you’re fully prepared for your upcoming race. Want to learn more about fueling strategies for performance? Be sure to read more on our blog at sooma.ca.

You can also book an appointment with one of our professionals directly by clicking this link.

Written by

Sophie Pilote

McGill Intern

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