Pre-event Carbohydrate Loading

Pre-event Carbohydrate Loading

Carbohydrate (carb) loading is a common practice for all major sporting events. As science is constantly evolving, so are our recommendations. As there are lots of different messages (and experiences) on the topic, Performance dietitian Conrad Goodhew (NZRD) takes us through the lowdown on loading. 


Why Carb Load?

Your body is only able to store enough carbohydrates (as glycogen) for exercise around 90 minutes long. After this, and without adequate fuel, this is where energy drops and fatigue sets in - more commonly known as hitting the wall.

Carb-loading aims to maximise our liver and glycogen stores to optimise performance. Carbohydrate loading can increase performance by 2-3% in some cases. This should be utilised for any race for more than 2h long (especially those full or multi-day events).


How much and for how long?

When I discuss this with my clients, I look at the length of an event. Shorter events, like a half marathon, I may consider a 1-2 day load. For week-on-week sports I would just focus on the day of competition (unless it is an early start). For longer events, from marathons to multi-sport (such as the coast to coast), loading of 3 days is recommended. However, I look like 4 days out as a 'prep load’ to help with the mindset.

For the 3 days of loading, carb recommendations are:

Males: ~8-10g per kg

Females: ~6-8g per kg

Use me for example, I am 80kg and I need 640-800g carbs per day. How much of this is in food? Read those labels, or you can use some online food tracking apps to help you gauge what foods to choose (or how much).

Carb depletion (cutting out carbs in the days before you start loading) is something that has been used in the past, however, recent evidence indicates it is no longer required.


What types of carbs should we aim to have?

That is really up to you as the individual. When people think of 'carb-loading', we automatically think of pizza and pasta. However, this is not always the case.

Things we do have to consider is how full we feel when we try to reach our target, as well as if we suffer from gastro disturbances - throw nerves in the mix and it can make things a bit more, well, shitty.

So simple ways to attack your load is:

4 days out: Change your snack options to carb-based ones. Think date scones, bran muffins, a couple of bananas, oat-based frooze balls etc.

3 days out: start to increase your portion of carbs at your main meals. Opt for a bigger bowel of oats for breakfast, 1/2 plate of carbs for dinner and lunch. Add in a couple of slices of bread in those meals too.

1-2 days out: Start to reduce your fibre and fat intake, this can reduce the load in your gut meaning you can consume more carbs. Look to add in some drinks that have carbs (sports drinks, orange juices, chocolate milk).

The night before: What is your comfort meal? Have this and increase the carb portion. This is where you just need to fall back on the meal that you enjoy the most. My go-to is mashed potatoes (with white bread), chicken thigh and mixed vegetables.

It is important to note that carb loading is not about binging on those foods you don’t normally have, however, high-fat foods can compromise your ability to consume adequate fuel, leaving you potentially physically and mentally fatigued.

The key tip is to ensure you write this out and note how you feel. This is vital for you to review and fine-tune for next time.


What about the morning of?

Your morning load should already have been practised during your training. However, if you have loaded adequately, this is more of a top-up. 1-4g of carbs per kg of body weight is recommended, with lower in fibre, protein and fat to ensure it is all digested properly.


Anything extra I should consider?


We often see electrolytes as something to have during and after the race, however, consider electrolytes the 2 days leading in. These can be useful to ensure adequate hydration, assist carb loading as well as preventing any gastro distress (caused by dehydration).

Blackcurrant supplementation

One of my all-time recommendations. Supplementing with 105-210mg anthocyanins from blackcurrant supplements for 7 days, including 1-2h before the race can significantly improve performance. It is also important to note that there are minimal reports of side effects in the literature, it is one of the supplements that will have minimal risk, even if you haven’t tried it before.

Beetroot supplementation

Supplementation of 310-560mg of nitrates 3h before exercise can enhance performance due to vasodilation (opening of the blood vessels). Intake of >3 days leading into a race has also shown significant performance increase. This is, however, a supplement that should be tested in training as it can cause gastro issues in some people. Note: If you have low blood pressure or are on blood pressure medication, please talk with a medical professional before you use it. 


Just a note on Fat as Fuel.

Being fat adapted is becoming trendy, however the evidence is still strong that if carbohydrate loading is still superior. It can take months, if not years, to become adequately adapted, but still is unable to show any benefits in the performance setting. So, if want to consider a more of fat as fuel approach, should be done alongside an experienced health professional.


For any individual advice or a last-minute check-in, please get in touch with Conrad Goodhew (NZRD)




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Kerksick CM, et al. International Society of Sports Nutrition position stand: Nutrient timing. Journal of the International Society of Sports Nutrition. 2017;14:33.

Vitale K and Getzin A. Nutrition and Supplement Update for the Endurance Athlete: Review and Recommendations. Nutrients. 2019;11:1289.

Braakuis AJ, Somervik VX, Hurst RD. The effect of New Zealand blackcurrant on sport performance and related biomarkers: a systematic review and meta-analysis. Journal of the International Society of Sports Nutrition. 2020;17:25.

Maughan RJ, et al. IOC consensus statement: dietary supplements and the high-performance athlete. British Journal of Sports Medicine. 2018; 52; 439-455.

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