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 this topic, we will summarise the current loading strategies including how and why.
WHY CARB LOAD?
Your body is only able to store enough carbohydrates (glycogen) during exercise for around 90 minutes. After this, and without adequate fuel, our 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 and has been shown to increase performance by 2-3% in some cases. This should be utilised for any race more than 2 hours long (especially those full or multi-day events).
HOW MUCH AND FOR HOW LONG?
When I discuss 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 a week-on-week sport, I would just focus on the day of the competition (unless it is an early start). For longer events, from marathons to multisport (such as the Coast to Coast), a loading of 3 days is recommended. However, I look at 4 days out as a ‘prep load’ to help with the mindset.
During a 3 day load, carb recommendations are:
Males: ~8-10g per kg
Females: ~6-8g per kg
For example, an 80kg person will need 640-800g of carbs per-day. How much of this is in food? Read those nutrition labels, or you can use food tracking apps to help you gauge what foods to choose (or how much).
Also, see our 50g Carb Sheet – you can download it here.
Carb depletion, which involves going low carb for a short period before your load, is something that has been used in the past. However, recent evidence indicates it is no longer required.
WHAT TYPE OF CARBS SHOULD WE AIM TO HAVE?
The type of carbs you consume is really up to you as the individual. When people think of ‘carb-loading’, we automatically think of pasta and pizza. However, this is not always the case.
The things we do have to consider are how we feel when trying to reach our carb targets, as well as if we suffer from gastro disturbances – throw nerves in the mix and it can make things a bit more, well, shitty.
Some simple ways to approach your load are:
4 days out: Change your snack options to carb-based ones. Think date scones, bran muffins, a couple of bananas, oat-based balls, etc.
3 days out: Start to increase your portion of carbs at your main meals. Opt for a bigger bowl of oats for breakfast and have ½ a plate of carbs for dinner and lunch. You could add a couple of slices of bread to those meals too.
1-2 days out: Start to reduce your fibre and fat intake. This can reduce the load in your gut and allow you to consume more carbs. Look to add in some drinks that have carbs (sports drinks, orange juice, 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 most and trust your stomach can tolerate. My go-to is mashed potato (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. High-fat foods can compromise your ability to consume adequate fuel, leaving you potentially physically and mentally fatigued.
The key 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 practiced during your training. However, if you have loaded adequately, this will be more of a top-up. 1-4g of carbs per kg of body weight is recommended and should be low in fibre, protein, and fat to minimise the risk of gastro disturbance.
ANYTHING EXTRA I SHOULD CONSIDER?
We often see electrolytes as something to have during and after the race, however, consider using electrolytes the two days leading into the race. These can be useful to ensure adequate hydration, assist carb loading, as well as preventing any gastro distress (caused by dehydration).
One of my favorite recommendations. Supplementing with 105-210mg anthocyanins from blackcurrant supplements for 7 days, including 1-2hr 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.
Supplementation of 310-560mg of nitrates 3hr before exercise can enhance performance due to vasodilation (opening of the blood vessels). Intake of >3 days leading into a race has also shown a 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 carbohydrate loading is still superior. It can take months, if not years, to become adequately adapted, but there is still little evidence to show any benefits in the performance setting. So, if you want to consider a more ‘fat as fuel’ approach, this should be done alongside an experienced health professional.
Blog written by Performance Dietitian and friend of Further Faster Conrad Goodhew. To get individualised recommendations (including calorie requirements), get in touch with him here: https://www.conradgoodhew.com.
If you enjoyed this blog, here's another one you might enjoy: How to avoid blisters and trench foot when adventure racing. (Gross feet images ahead!)
Delfique L, et al. Recommendations for healthy nutrition in female endurance runners: A update. Frontiers in Nutrition. 2015;2:17
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. Nutrition and Supplement Update for the Endurance Athlete: Review and Recommendation. 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.