Carbohydrate loading is a nutrition strategy used by endurance athletes prior to a big event. Carbohydrate loading involves increasing carbohydrate intake for 1-2 days before the event to increase glycogen stores for improved performance.
What are carbohydrates?
Carbohydrates are essential macronutrients and the body’s main source fuel during exercise. When carbohydrates are consumed, the body converts them into glucose. Unused glucose is stored in the form of glycogen for later use. Carbohydrates are found in the form of sugars, starches, and dietary fibre. Food sources that are high in carbohydrates include bread, pasta, rice, fruit, starchy vegetables, dairy products, cakes, lollies, soft drink, and fruit juice.
What is the benefit of carbohydrate loading?
The muscles can only hold enough glycogen to provide approximately 90 minutes’ of exercise. Without sufficient refueling, it can cause fatigue and a drop in performance. Carbohydrate loading will saturate the muscles in glycogen, providing the optimal fuel state for an intensive endurance event.
Who would benefit from carbohydrate loading?
Events lasting longer than 90 minutes are generally considered an endurance event and those longer than 4 hours are ultra-endurance. Exercise that does not exceed 90 minutes and is not intensive does not require carbohydrate loading, however, consuming carbohydrates on the day of the event will fuel performance. Unnecessary carbohydrate loading can lead to excess weight gain.
Consider saving a carbohydrate load for big events that last longer than 90 minutes, such as marathons, triathlons, multiple events/ games in one day, martial arts grading, ironman, or long-distance cycling. Bodybuilders can consider carbohydrate loading prior to stepping on stage to make muscles appear fuller.
What types of carbohydrates should be consumed during a loading phase?
To get optimal benefits from a carbohydrate load, it is important to consume the right carbohydrates. High GI and low fibre carbohydrates are the most rapidly absorbed and present the fewest gut issues.
Side effects of carbohydrate loading
Despite being a safe practice, carbohydrate loading may cause side effects. Carbohydrates hold onto water, approximately 3g of water per 1g carbohydrate. For example, if you were to consume 100g of carbohydrates, the scales will increase by 400g total. This will cause a temporary gain in weight; however, is not a concern and weight will return to normal within a few days following the event.
Another common side effect of increasing carbohydrate intake is feeling sluggish or tired. To avoid any problems occurring, it is recommended to trial a carbohydrate loading phase prior to the event. Talking to a healthcare professional can help ease any concerns regarding carbohydrate loading and aid in finding the right carbohydrates for you.
Steps to a carbohydrate load
Carbohydrate loading involves the consumption of 7-12g carbohydrate per kg of body weight, however this may vary for each individual. For example, a 75kg athlete would consume 525-900g carbohydrates to achieve a successful carbohydrate loading phase. It is recommended to begin a carbohydrate loading phase 1-2 days (36-48 hours) prior to the event. Ensure to plan out your food intake before consumption to ensure the carbohydrate loading it done successfully.
Other important considerations:
· Pair carbohydrate loading with tapered exercise to promote optimal storage of glycogen and minimise depletion
· Ensure adequate water consumption
· Opt for low fibre/ high GI carbohydrates to minimise gut discomfort
· Research suggests a depletion phase is not necessary
· Avoid eating foods high in fat and protein during the carbohydrate loading phase to avoid eating an excess of calories
Examples of foods high in carbohydrates
Food source Carbohydrates (g)
50g glucose 50g
100g lollies 75g
2 slices white bread 30g
30g Cyclyte electrolyte powder 23g
1 apple 14g
On the day of the event
Carbohydrate consumption on the day of the event is just as important, particularly as carbohydrates are the body’s preferred source of fuel for exercise. Since the body can only store enough glycogen for about 90 minutes of exercise, pre- and intra-event refueling is an important consideration.
Consuming a high carbohydrate meal 3-4 hours prior to the event and a high carbohydrate snack 1-2 hours before has been observed as the best fueling approach. For endurance events, consumption of 30-60g of carbohydrates/ hour of exercise is the recommended amount for optimal performance. For ultra-endurance events, up to 90g of carbohydrates/ hour of exercise can be consumed.
It is recommended to avoid consuming large amounts of protein, fat and fibre prior to an event as it may cause gastrointestinal discomfort. Ensure water and electrolyte intake is adequate during the event to prevent dehydration and muscle cramping.