How to Carb Load Before Your Race

Carb loading is a strategy many runners hear about but often misunderstand.

Carb loading

The goal is simple: maximize your muscle glycogen stores to fuel your race.

Yet, many focus on the wrong timing or the wrong foods.

This guide breaks down how to carb load effectively for different race distances—from half marathons to ultra races like 50K—and explains when the most important meal actually is.

Let’s break this down simply and practically.

Easy-to-follow guidelines to help you cross the finish line strong.

Carb-loading meal focuses on easily digestible carbs like white rice, paired with lean protein.

Why Carb Loading Matters for Runners

Carbohydrates are the primary fuel source during endurance running. Your muscles store carbs as glycogen, which your body taps into during long runs. When glycogen runs low, fatigue sets in, and performance drops. Carb loading helps fill these stores to delay fatigue and improve endurance.

Many runners think the key carb meal is the night before the race. In reality, the most important carb intake happens two to three days before your race.

This timing allows your muscles to fully replenish glycogen stores.

Timing Your Carb Loading for

Different Race Distances

The amount of carbs you need and when you should start loading depends on your race distance.

Here’s a breakdown:

Half Marathon (13.1 miles)

• Start carb loading: 1-2 days before race day

• Carb target: About 5-7 grams of carbs per kilogram of body weight per day (2.3-3.2 grams per pound)

• Example: For a 150-pound runner, aim for 345-480 grams of carbs daily

• Meal focus: The meal two nights before the race is key. For a Saturday race, Thursday night’s dinner should be rich in carbs.

• Foods to choose: White rice, white bread, pasta, potatoes, and simple carbs like fruit gummies (yes, your kids’ gummies work well!)

30K Race (18.6 miles)

• Start carb loading: 2 days before race day

• Carb target: 6-8 grams of carbs per kilogram of body weight per day (2.7-3.6 grams per pound)

• Example: For a 150-pound runner, aim for 405-540 grams of carbs daily

• Meal focus: The meal two nights before the race is the most important, with a carb-rich dinner and balanced meals the day before.

• Foods to choose: White rice, white bread, potatoes, and simple carb snacks

Full Marathon (26.2 miles)

• Start carb loading: 2-3 days before race day

• Carb target: 7-10 grams of carbs per kilogram of body weight per day (3.2-4.5 grams per pound)

• Example: For a 150-pound runner, aim for 480-675 grams of carbs daily

• Meal focus: The two nights before the race are critical. For a Sunday race, Friday and Saturday dinners should be carb-heavy.

• Foods to choose: White rice, white bread, bagels, low-fiber pasta, and carb-rich snacks like fruit gummies or sports gels

  
  

50K Ultra (31 miles)

• Start carb loading: 3 days before race day

• Carb target: 8-10 grams of carbs per kilogram of body weight per day (3.6-4.5 grams per pound)

• Example: For a 150-pound runner, aim for 540-675 grams of carbs daily

• Meal focus: Carb loading should start early, with three days of carb-rich meals. The dinner two nights before race day is crucial.

• Foods to choose: White rice, white bread, pasta, potatoes, and carb-rich snacks for easy digestion

  
  

Why White Carbs Are Better Than

Whole Grains Before a Race

During carb loading, choose white rice, white bread, and low-fiber pasta over whole grains. These foods digest faster and help fill glycogen stores without causing digestive discomfort. Whole grains have more fiber, which can cause bloating or stomach issues during your race.

For example, swap your usual brown rice for white rice, and choose bagels or white bread instead of whole wheat. This switch helps your body absorb carbs quickly and keeps your stomach calm.

Practical Carb Loading Meal Ideas

Here are some simple meal ideas for your carb-loading days:

• Dinner two nights before race day: Grilled chicken breast, white rice, steamed carrots, and a small side of fruit gummies for a carb boost

• Lunch: Turkey sandwich on white bread with honey mustard and a banana

• Snacks: Fruit gummies, pretzels, rice cakes, or a sports drink with carbs

• Breakfast: Bagel with jam and a glass of orange juice

  
  

How to Calculate Your Carb Needs

To find your daily carb target, multiply your weight in pounds by the grams of carbs per pound recommended for your race distance. Here’s a quick reference:

Spread these carbs over 3-5 meals and snacks each day.

Avoid overeating in one sitting to prevent discomfort.

What to Expect on Race Day

It’s normal to feel a bit heavy or bloated standing at the start line after carb loading. Your body is holding extra glycogen and water. Don’t worry—this feeling usually fades during the race. The extra fuel will help you maintain energy and finish strong.

Final Tips for Successful Carb Loading

• Hydrate well during your carb-loading days to help glycogen storage.

• Avoid high-fat and high-fiber foods in the days leading up to race day to prevent stomach issues.

• Practice your carb-loading strategy during training to see what works best for you.

• Listen to your body and adjust portions if you feel uncomfortable.

  
  

  Happy Balanced Running

  Dayna - your fav. Exercise Physiologist & Run Coach