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5 carbo-loading myths busted

Should you be carbo-loading before your 10km race? Probably not, but a marathon is a different story. We uncover a few other misconceptions.

One small thing: Stick to smaller portion sizes and choose low-fibre carbohydrates before the day of your big race.

If you know anything about running and cycling, you’ve probably heard about carbo-loading. But who should carbo-load? And more importantly, how do you do it correctly?

Why our bodies need carbs

Carbohydrates are a macronutrient that provides energy. When you exercise, your body uses even more energy, especially during prolonged endurance events such as marathons, cycle races or triathlons.

Your muscles and liver store carbohydrates in the form of glycogen. When your glycogen levels dip too low, you feel fatigued and may experience muscle cramps.

Who needs to carbo-load?

While some carbohydrates are good to energise you during a normal day, you’ll need more carbohydrates if you are an endurance athlete.

According to registered dietitian Leanne Kiezer carbo-loading is an important strategy for events lasting longer than 90 minutes, such as marathons, prolonged cycling races or triathlons where the same muscle group is being used continuously.

The goal is to ensure you have enough glycogen stored in your muscles and liver to get you through the entire event.

So, if you’re a keen runner who likes to tackle the occasional 10km race, carbo-loading is probably not for you.

Common myths about carbo-loading

Carbo-loading isn’t about devouring plates of pasta and pizza before your big event. According to Kiezer, these are the common mistakes people make:

1. Carbo-loading hours before the event

Carbo-loading should be planned days before your big race. Increase your carbohydrate intake 36 to 48 hours before an endurance event, not the night before, as this can leave you feeling bloated. The recommended intake is about 10-12g of carbohydrate per kilo of body weight per day.

2. Choosing carbohydrates high in fibre

While wholegrain sources rich in fibre are often the healthiest form of carbs, too much fibre can wreak havoc on your performance. You might experience indigestion issues, such as cramps or diarrhoea, if you consume too much fibre right before your big event. Your best bet is to stick to bland, low-fibre carbs such as potatoes, white bread or pasta.

3. Including too much fat

You might be tempted to load up on fries or pizza before your marathon, but that’s a big no-no. To maximise your carbohydrate intake, choose foods that are low in fat, says Kiezer. High-fat foods take longer to digest and may cause you to feel too full. You might also experience indigestion during your event.

4. Increasing portion sizes significantly

You might feel tempted to increase your portion sizes – this will only lead to over-eating and feeling uncomfortable. Remember, the rule of thumb is 10-12g of carbs for every kilogram you weigh.

This menu offers a guide for what to eat in those two days before an event:

Breakfast 2 cups low-fibre cereal with low-fat milk
1 fresh fruit
2 slices wholewheat toast with jam
1 glass fruit juice
Snack 1 low-fat muesli bar
1 fresh fruit
Lunch 2 rolls or bagels, 1 filled with meat and salad, 1 filled with sliced banana and honey
1 cup canned fruit
1 tub low-fat fruit yoghurt
Snack Smoothie made from ½ cup fruit salad, 1 cup low-fat milk and 2 scoops low-fat fruit yoghurt
Dinner 2 cups pasta, noodles or rice with a vegetable-based sauce
200g low-fat sago or rice pudding with 1 diced mango or other seasonal fruit
Snack 1 hot cross bun or 2 rusks


5. Carbo-loading for every race, big or small

Carbo-loading is only applicable to big endurance events and may lead to weight gain if done regularly for smaller races.

If you have a question for our dietitians, click here, or to find a dietitian in your area, visit To get in touch with us, email


Burke L, Deakin V (2010). Clinical Sports Nutrition, 4th Ed. McGraw-Hill, Australia.