Carb Loading: The Science-Backed Strategy to Go the Distance

From how much to eat to what to avoid, this guide breaks down carb loading for real-world athletes who want results.

Suppose you’re getting ready for a marathon, triathlon, or endurance event. In that case, you’ve probably heard of carbohydrate loading, a strategy used to maximise energy stores before race day or an intense workout.  Whether it's necessary for everyone depends on factors such as duration, intensity, and individual needs. If you’ve ever wondered if carb loading is right for you, how it works, or when it might be useful, this guide breaks it down. 

Why are carbohydrates important?

Carbohydrates are the body’s preferred energy source, fuelling both your muscles and your brain. They supply quick-access fuel and are stored as glycogen in your muscles and liver for sustained energy during exercise. In endurance sports, these glycogen stores are essential for maintaining performance. Research also shows that glucose is vital for brain function, and inadequate carbohydrate intake can impair cognitive performance.

So, if I’m exercising, how much carbohydrate should I consume daily? 

What is carbohydrate loading?

Carb loading is a well-known nutrition strategy that increases glycogen stores in muscles by consuming more carbohydrates before intense physical activity. With more glycogen available, this may improve endurance and sustain energy levels during prolonged exertion. 

When & how to carb load effectively? 

Carb loading is most beneficial for endurance athletes in events longer than 90 minutes, as it helps sustain energy levels and delays fatigue. Modern carb-loading strategies focus on shorter, high-carb phases. Research published in the International Journal of Sports Nutrition and Exercise Metabolism recommends consuming 10-12g of carbohydrates per kilogram of body weight over 36-48 hours pre-race to maximise glycogen stores. Carb loading works best when combined with tapering your training in the final days before a competition.

For a 60kg athlete, this equates to 600-720g of carbohydrates per day, while a 70kg athlete would aim for 700-840g. Research also shows that elevated muscle glycogen levels can postpone fatigue by around 20% in endurance events exceeding 90 minutes. 

A well-practiced, personalised plan ensures optimal fueling for peak performance.

Common carb-loading mistakes:

1. Unnecessary Carb Loading: Designed for endurance events lasting over 90 minutes, carb loading isn’t needed for shorter workouts and may lead to excess calorie intake without a performance benefit.

2. Too much fibre: Eating too much fibre before an event may cause digestive discomfort.

3. Not tapering workouts: Maintaining intense training while carb loading can deplete glycogen stores instead of maximising them, reducing the benefits of the strategy.

What are the best foods for carb loading?

Carb loading isn’t just about eating huge pasta bowls. Instead, focus on increasing the carb content of your meals by adding larger servings of your preferred carbohydrate sources. The goal is to increase your carb intake compared to a typical day without significantly raising overall calories. To achieve this, adjust your macronutrient balance by reducing fat and protein to make room for extra carbs. Stick to familiar, easy-to-digest foods and focus on eating small, frequent meals.

Great carbohydrate-rich foods include pasta, rice, oats, bananas, jacket potatoes, and bagels.

For inspiration, here are options for carb-rich meals for Carb Loading:

🥣 Porridge with fruit and honey
🥯 Bagel with jam
🍌 Smoothie with banana, oats, and honey
🍝 Pasta with tomato sauce or pesto
🥔 Jacket potato with toppings, such as baked beans
🍠 Sweet potato with quinoa and a drizzle of olive oil
🍜 Tofu and vegetable stir-fry with rice or noodles
✅ For a quick and convenient option, try Huel Ready-to-Drink 

Words: Jessica Stansfield, RNutr, Nutrition Manager