How To Carb Load For A Marathon

Carbohydrate loading, also known as carb loading, is a crucial strategy for marathon runners to optimize their performance. As an avid runner myself, I have experienced the benefits of carb loading firsthand. In this article, I will share with you my personal insights on how to effectively carb load for a marathon.

What is Carb Loading?

Carb loading is the process of increasing your carbohydrate intake in the days leading up to a marathon. The goal is to maximize your glycogen stores, which are your body’s primary source of energy during endurance activities like running a marathon.

During carb loading, you will consume a higher percentage of carbohydrates than usual and reduce your intake of fats and proteins. This allows your muscles to store more glycogen, which can provide a longer-lasting fuel source during your marathon.

When to Start Carb Loading

The ideal time to start carb loading is 2-3 days before your marathon. This gives your body enough time to fully replenish its glycogen stores. Starting too early may lead to feeling heavy and sluggish on race day, while starting too late may not provide enough time for optimal glycogen storage.

Choosing the Right Carbohydrates

Not all carbohydrates are created equal when it comes to carb loading. It’s important to choose complex carbohydrates that are rich in fiber and nutrients. Some excellent options include whole grains, fruits, vegetables, and legumes.

Avoid simple carbohydrates, such as refined sugars and white bread, as they can cause spikes in blood sugar levels and lead to energy crashes. It’s also important to steer clear of greasy or heavy foods that can cause digestive issues during the race.

How Much to Carb Load

The amount of carbohydrates you need to consume during carb loading depends on your body weight and training volume. A general guideline is to aim for around 7-10 grams of carbohydrates per kilogram of body weight per day.

For example, if you weigh 70 kilograms, you should aim to consume between 490 and 700 grams of carbohydrates daily during the carb loading phase. It may sound like a lot, but by spreading it out over several meals and snacks throughout the day, it becomes more manageable.

Sample Carb Loading Plan

Here’s a sample carb loading plan for the day before a marathon:

  1. Breakfast: Start the day with whole grain toast topped with nut butter and a side of fruit.
  2. Mid-Morning Snack: Enjoy a Greek yogurt with berries and a sprinkle of granola.
  3. Lunch: Have a generous serving of pasta or rice with grilled chicken or tofu and a variety of colorful vegetables.
  4. Afternoon Snack: Grab a banana and a handful of nuts for sustained energy.
  5. Dinner: Opt for a lean protein like fish or lean cuts of meat, accompanied by a side of quinoa and steamed vegetables.
  6. Evening Snack: Indulge in a small bowl of oatmeal topped with sliced banana and a drizzle of honey.

Remember to stay hydrated throughout the day by drinking plenty of water or sports drinks. Hydration plays a crucial role in carbohydrate absorption and muscle function.

The Day of the Marathon

On the day of the marathon, it’s essential to have a balanced pre-race meal that includes carbohydrates, proteins, and a small amount of healthy fats. This will provide you with sustained energy and prevent any digestive discomfort.

Avoid trying anything new on race day. Stick to familiar foods that you have tested during your training runs, as you don’t want to risk any gastrointestinal issues or unexpected reactions.


Carb loading is a tried-and-true strategy to optimize your performance and fuel your body for a marathon. By following a well-planned carb loading plan and choosing the right types and amounts of carbohydrates, you can ensure that your glycogen stores are fully stocked on race day.

Remember, what works for one person may not work for another, so it’s essential to experiment during your training to find the carb loading strategy that works best for you. Trust your body, listen to its cues, and make adjustments accordingly.

Now go out there and conquer that marathon with your glycogen-loaded muscles!