The One Thing: Carb loading and how to do it properly – with help from HYROX

Just as important as having the right gear (hello, new trainers) is having the right nutrition in the run-up. And that’s where carb loading comes in. This simple nutrition strategy promises to help you run further, lift longer and cycle faster, by making subtle tweaks to your diet in the days and hours leading up to the big day. 

To help us understand the how, when and why of carb loading, we asked top sports nutritionists and endurance athletes to run us through the basics. See you on the starting line…

“In its simplest form, it involves supplying your body with higher amounts of carbohydrates before an event, match or competition.”

The science behind going hard and fast on carbs is pretty simple, he explains: “At a biological level, your body uses the glycogen stored in your muscles to provide the energy needed for exercise. It produces this glycogen by breaking down the carbohydrates you eat. So, by eating more carbohydrates, you’re essentially adding more petrol to the tank and providing your body with the vital energy stores it needs to dig deep during a long-distance effort.” Put another way, more carbs means more fuel.

Jake adds that carb loading can help you to avoid hitting total glycogen depletion too. Known in workout circles as ‘bonking’ – or simply ‘hitting a wall’ – it marks the point at which the body’s glycogen stores have run out, making each step towards the finish line torturously difficult.

While carb loading might sound like yet another TikTok buzzword, it has an impressive amount of peer-reviewed scientific research to back up its benefits. One study review¹ found that prioritising carbs before an event lasting 90 minutes or more may improve your athletic performance by 2-3%. Encouragingly, the same researchers found that it could also potentially postpone mid-race fatigue by as much as 20% too.

“Ideally you want to spend the 48 to 72 hours before race day building up your glycogen stores,” Dr Collins advises. In practice, this looks like three carb-based meals with a mid-morning and afternoon snack slotted in between. 

But don’t worry if maths isn’t your strong point; nutrition tracking apps can do the hard work for you. MyFitnessPal has a handy log feature that allows you to input your meals and portion sizes so you can monitor your carb intake as you inch closer to the starting gun. Simples.

"Carb loading is one instance where we recommend steering clear of high-fibre options like wholegrains and beans as they stay in your digestive tract longer than low-fibre carbohydrates, which might cause digestive problems on race day. Instead, focus on consuming easily digestible, high-carb foods like white bread and white rice over wholegrains and reduce your intake of beans and high-fibre vegetables,” says Emily. 

“While carb loading involves increasing your carbohydrates compared to a regular day, it doesn’t mean you should increase your total daily calorie intake too. You’ll need to reduce fat and protein intake to balance the increase in carbohydrates. Reducing fat intake is recommended close to races anyway, as fats are harder to digest and can cause digestive upset.”

Whet your appetite? Emily has some tasty suggestions for counting up those carbs.