Carb Loading for Endurance Athletes | A Sports Nutritionist Approach

May 15, 2023

Carbohydrate loading is a strategy that athletes use to increase the amount of glycogen, or stored carbohydrates, in their muscles before an endurance event. While the concept of carb loading is widely known, the scientific principles of carbohydrate loading are not always correctly applied. The following considerations will help you effectively implement a carb loading strategy to improve your performance in endurance events!


1. Ensure you benefit from a carb load

Endurance events that last longer than 90 minutes benefit from up to 2 days of carbohydrate loading to maximize liver and muscle glycogen. Events lasting less than 90 minutes do not require a multi day carb load but do benefit from adequate carbohydrate consumption in the 24 hours before the event. It’s important to note that carbohydrate loading is a performance strategy for race day and is not recommended for general healthy eating or a nutrition strategy to utilize during training. 

2. Determine your target carbohydrate goal

The carbohydrate requirements to promote glycogen load vary with a recommended intake of 6g/kg/day for events <90 minutes and between 10-12g/kg/day for events >90 minutes. Individual needs vary based on tolerance, current carbohydrate intake, and performance level. It is important to work with a Registered Dietitian like the nutritionists at Vitality Nutrition to determine your specific carbohydrate loading target.

3. Carbohydrate load for the correct duration. 

Endurance events lasting >90 minutes benefit from 36-48 hours of carb loading (~2 days) prior to the race. Endurance events lasting <90 minutes require only a 24 hour (1 day) carbohydrate load prior to the race.

4. Eat a high carb meal 1-4 hours before the event

In the final 1-4 hours before the event it is recommended to ingest 1-4g/kg of carbohydrate to top off liver glycogen stores. The amount of carbohydrate in the pre-race meal is dependent on the athlete’s preference and gastrointestinal tolerance prior to the event.

For example, a 65 kg runner would consume a minimum of 65g of carbohydrate and up to 260g of carbohydrate in their pre-race meal. This may equate to a bagel (50g of carbs) with peanut butter, sliced banana (25g of carb), and a tablespoon of honey (20g of carb) for a total of 95g of carbohydrate.

5. Reduce your fibre intake during your carbohydrate load and prior to the event

Fat and fibre are important nutrients to optimize health and digestion respectively. However, high fibre and high fat foods take longer to digest and may cause gastrointestinal distress before or during the race. Furthermore, foods with fat and fibre are filling and can reduce appetite making it difficult to achieve the high carbohydrate recommendations of the carbohydrate loading protocol. Athletes may benefit from lower fibre carbohydrate sources and a reduced fat intake during the carbohydrate load. For example:

  • Instead of whole grain bread choose a lower fibre sourdough or rye bread.
  • Instead of high fibre fruit like berries and apples choose lower fibre fruits like tropical fruits, grapes, and melon
  • Instead of a high-fibre cereal (eg. Shreddies or oatmeal) choose a lower-fibre cereal (eg. Chex or cream of rice)
  • Instead of minimizing added sugars choose sweetened products like a vanilla Greek yogurt instead of plain Greek yogurt
  • Instead of minimizing refined sources of carbohydrate choose ingredients like jam, maple syrup, or honey to boost carbohydrates.

Some athletes may need to intentionally reduce fat sources during their carbohydrate load to optimize appetite and digestion. High fat foods include nuts, nut butters, oil, avocado, higher fat protein sources like pork or beef, dips like hummus, and cheese.

6. Eat a variety of carbohydrate sources in the carb load phase

Carbohydrate loading pasta meals have become synonymous with long distance events. However, carbohydrate loading is not confined to pasta and can include a variety of lower-fibre carbohydrate sources such as bread, crackers, pancakes or waffles, rice, rice noodles, potato, tropical fruits, sweetened yogurt, dried fruits, jam, maple syrup, and honey. A Registered Dietitian can help you optimize the types and amounts of carbohydrate you consume for your individual needs. The list below provides approximate amounts of carbohydrates per portion.

  • 1 cup pasta, cooked (40g)
  • 1 cup rice, cooked (45g)
  • 1 cup quinoa, cooked (40g)
  • 1 cup oatmeal, cooked (30g)
  • 1 cup potato, cooked (35g)
  • 1 cup cream of rice, cooked (35g)
  • 2 slices bread (30g)
  • 1 bagel (55g)
  • 1 waffle (25g)
  • 3 pancakes (30g)
  • 1 large pita (35g)
  • 1 large wrap (30g)
  • 4 rice cakes (28g)
  • 13 rice crackers (20g)
  • 1 cup cereal (25g)
  • ½ cup granola (30g)
  • 1 piece (~1 cup) fruit (25g)
  • 1 cup juice (25g)
  • ¼ cup dried fruit (30g) 
  • 1 tablespoon honey (15g)
  • 1 tablespoon maple syrup (15g)
  • 1 tablespoon jam (15g)

7. Work with a Registered Dietitian to optimize your nutrition strategy

The ideal carbohydrate loading plan depends on your event, body composition, and typical eating patterns. Furthermore, nutrition planning for intra-competition fueling is an important consideration to optimize energy and performance. This includes the ingestion of carbohydrate, fluids, and electrolytes during the event. It's best to seek support from a Registered Dietitian with experience in sports nutrition to create the perfect plan for you!


Key Takeaways

A multiple day carbohydrate loading strategy is recommended for athletes competing in endurance events >90 minutes. Athletes competing in endurance events lasting <90 minutes may benefit from “topping-off” glycogen stores by consuming an adequate carb intake for one day prior to the event. Carbohydrate loading is a performance nutrition strategy for endurance athletes and is not recommended as a nutrition approach for training or general healthy eating. Since the ideal carb loading plan depends on your event, body composition, and current eating patterns it’s best to seek advice from a Registered Dietitian with experience in sports nutrition to create the perfect plan for you.

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