Carbo-Loading Before the Marathon: The 7 Most Important Tips & Example Schedule

A marathon is not only a physical test but also a matter of proper energy supply.

To successfully cover the distance of 42.195 kilometers, not only months of preparation are required, but also precise nutrition in the final week before the race.

This is where so-called carbo-loading comes into play. It is a proven method to deliberately fill the carbohydrate stores in the body, allowing runners to rely on maximum energy reserves during the race. When done correctly, it can make the decisive difference between a successful run and an unexpected drop in performance in the last kilometers.

Why a Fully Stocked Carbohydrate Store is Crucial

The most important energy source for endurance athletes is carbohydrates. During a marathon, the body primarily relies on glycogen stored in the muscles and liver. These glycogen stores largely determine how long a runner can perform at high intensity before having to rely on alternative energy sources such as fat.

The point at which glycogen stores are depleted is often described as "hitting the wall." Runners report a strong drop in performance, forcing the body to drastically reduce pace or even quit entirely. Carbo-loading is the strategy to maximize glycogen stores before the race and thus avoid this low. Studies show that well-stocked carbohydrate stores can significantly improve endurance performance.

The 7 Most Important Tips for Carbo-Loading Before the Marathon

1. Start Planning Early

Carbo-loading does not start the day before the race but should be planned several days in advance. Ideally, you begin three to five days before the marathon with a targeted increase in carbohydrate intake. It is not enough to just stuff yourself with pasta the night before — this method can lead to digestive problems and bloating.

2. Choose the Right Carbohydrates

Complex carbohydrates such as whole-grain pasta, oats, potatoes, and quinoa are ideal to sustainably fill glycogen stores over several days. Avoid simple sugars and highly processed carbohydrates, as they can cause blood sugar fluctuations.

3. Watch Protein and Fat Intake

While increasing your carbohydrate intake, it is important to reduce fat intake. Fats slow down digestion and prevent rapid glycogen replenishment, even if only slightly. Keep your protein intake moderate to support muscle repair without hindering carbohydrate absorption.

4. Drink Enough Fluids

Because glycogen binds water in the body, you need more fluids than usual during carbo-loading. Make sure to drink enough to avoid dehydration and to optimize glycogen storage.

5. Spread Carbohydrates Throughout the Day

Consuming too many carbohydrates in one meal can cause digestive problems. Instead, distribute your carbohydrate intake evenly across all meals. Snacks like bananas, dates, or energy bars can be included.

6. Do Not Try New Foods

The biggest mistake is trying new foods or diets shortly before the marathon. Your digestive system needs stability in the week before the marathon. Stick to foods you know you tolerate well.

7. Adjust Quantities to Your Body Size

The amount of carbohydrates you consume should be tailored to your body size and training condition. A general recommendation is about 7 to 10 grams of carbohydrates per kilogram of body weight per day.

From Which Race Distance is Carbo-Loading Important?

Carbo-loading is not necessary for every run. The method is mainly recommended for races lasting longer than 90 minutes, such as half marathons, marathons, and ultra runs. For shorter distances like a 10 km run, glycogen stores are usually sufficient, so no special loading is needed. Nevertheless, even for these runs, you should not start with completely depleted energy stores.

For runs lasting two hours or longer, carbo-loading is an essential component for successful performance.

Example Schedule: Carbo-Loading in the Week Before a Marathon

A well-structured carbo-loading program should be carried out over several days. Here is an example for the last week before a marathon:

For a structured and targeted marathon preparation, we recommend the "Big Running Book of Training Plans".

Differences Between Men and Women in Carbo-Loading

Women and men have different physiological conditions regarding carbo-loading. Studies show that women generally store fewer carbohydrates than men. One reason is hormonal fluctuations, especially estrogen, which favors fat metabolism. To compensate, women may need to aim for an even higher carbohydrate or calorie intake during carbo-loading. Scientific sources recommend about 20 to 30 percent additional calorie intake for women.

Additionally, the menstrual cycle affects the effectiveness of carbo-loading. Women benefit particularly during the first half of the cycle (follicular phase) from better glycogen storage. This should be considered in planning.

Common Mistakes in Carbo-Loading and How to Avoid Them

Even though carbo-loading is a relatively simple method, mistakes often occur that reduce its effectiveness. The most common are:

• Too many carbohydrates at once: Consuming large amounts of carbohydrates in a short time can cause digestive problems. Spread the intake over several meals.
• Insufficient fluid intake: Carbo-loading requires additional water to fully utilize glycogen stores.
• Ignoring training status: Runners with low glycogen stores (due to training or diet) benefit more from carbo-loading than well-trained runners who already regularly fill their stores.

Summary