Carbohydrate Loading for Endurance Events: What Actually Works

Carbohydrate loading is one of the most talked-about race preparation strategies in endurance sports, and unfortunately, one of the most misunderstood.

Athletes often hear recommendations to consume massive amounts of carbohydrates in the days before a race. While there is science behind increasing carbohydrate intake before a long event, many athletes end up bloated, sluggish, and uncomfortable because they focus on the numbers instead of the purpose.

The goal of carbohydrate loading is simple:

Increase glycogen stores so you have more readily available fuel for race day.

The good news is that if your taper is structured correctly, much of this happens naturally.

Understanding the Taper

When you’re training hard, two things are happening simultaneously:

  • Fitness is increasing.

  • Fatigue is accumulating.

The purpose of a taper is to reduce fatigue while maintaining as much fitness as possible.

Think of it like this:

  • Fitness is very high.

  • Fatigue is also very high.

As training volume decreases, fatigue drops rapidly while fitness decreases only slightly. The result is an athlete who is fresher, more recovered, and able to perform at their highest level on race day.

At the same time, glycogen stores begin to refill because you’re doing less work and using less fuel. This is one reason tapering works so well.

Why Glycogen Matters

Glycogen is stored carbohydrate in the muscles and liver. It is the primary fuel source for moderate to high-intensity exercise. No matter how efficient an athlete becomes at utilizing fat, glycogen is still required to produce race-level intensity. This is why athletes cannot race hard on low-carbohydrate or fat-only fueling strategies. When intensity increases, carbohydrate becomes essential. The goal before a race is to start with full glycogen stores and then continue replacing carbohydrates during the event.

The Biggest Carb Loading Mistake

Many athletes dramatically increase their carbohydrate intake all at once.They start calculating grams per pound of body weight, force-feeding themselves large bowls of pasta, and trying to hit exact numbers.

What often happens?

  • Bloating

  • Water retention

  • Sluggishness

  • Stomach discomfort

  • Feeling heavy on race morning

I’ve seen this repeatedly throughout my own racing career and with athletes preparing for long-course events.

The problem isn’t carbohydrates.

The problem is trying to force-feed carbohydrates when your body is already naturally replenishing glycogen through reduced training.

A Practical Approach to Carb Loading

Instead of obsessing over exact formulas, I prefer a more practical approach.

For the final 48-72 hours before a race:

Eat More Frequently

Consume small meals and snacks every 2-3 hours.

Shift Toward More Carbohydrates

Gradually increase carbohydrate-rich foods while reducing foods that are harder to digest.

Examples include:

  • Potatoes

  • Sweet potatoes

  • White rice

  • Oatmeal

  • Bagels

  • Bread

  • Pretzels

  • Bananas

  • Sports drinks

  • Applesauce

  • Rice cakes

Reduce Fiber

As race day approaches, reduce foods that create excessive digestive workload.

Limit:

  • Large salads

  • Raw vegetables

  • Beans

  • High-fiber cereals

  • Brown rice

Fiber is healthy most of the year, but immediately before racing it can increase gastrointestinal stress.

Keep Protein Lean

During the final 48 hours, focus on:

  • Chicken

  • Fish

  • Eggs

Reduce:

  • Red meat

  • Pork

  • Heavy fatty foods

These foods generally digest more slowly and can leave athletes feeling heavy.

What Carb Loading Meals Might Look Like

Breakfast

Instead of:

  • Fruit and yogurt

Try:

  • Oatmeal

  • Bagel with peanut butter

  • Banana

Lunch

Instead of:

  • Large salad with lean protein

Try:

  • Rice bowl with chicken

  • Baked potato and fish

  • Turkey sandwich on white bread

Dinner

Excellent race-week dinners include:

  • Baked potato and chicken

  • Sweet potato and salmon

  • White rice and grilled fish

  • Pasta with chicken and a simple sauce

The goal is not to stuff yourself. The goal is to consistently provide your body with carbohydrates while allowing digestion to remain easy.

What About Exact Carb Loading Formulas?

Research often recommends:

  • 8-12 grams of carbohydrate per kilogram of body weight per day

For some athletes, this works well.

For many age-group athletes, trying to force these numbers becomes stressful and uncomfortable.

Remember:

Carbohydrate loading should make you feel fueled, not stuffed.

If you’re feeling bloated, lethargic, or uncomfortable, you’ve likely overdone it.

Race Distance Matters

Sprint and Olympic Distance

Minimal carbohydrate loading is needed.

Normal healthy eating and proper tapering are often enough.

Half Ironman / 70.3

A modest increase in carbohydrate intake for 48 hours before the race is usually sufficient.

Most athletes do not need extreme carb loading strategies.

Ironman and Ultra-Endurance Events

A more deliberate carbohydrate-loading approach becomes beneficial because glycogen availability can significantly impact performance later in the race.

Even then, gradual increases work better than trying to consume enormous amounts of food the night before.

Hydration and Sodium Matter Too

Carbohydrates and glycogen are stored with water.

As glycogen stores increase, fluid requirements increase as well.

During race week:

  • Drink consistently throughout the day. Not over doing it with plain water.

  • Include electrolytes if temperatures will be hot.

  • Add sodium to meals.

  • Monitor urine color rather than forcing excessive fluid intake.

The goal is to arrive hydrated, not overhydrated.

Race Morning Nutrition

Race morning is not the time to experiment. Eat foods that you know sit well in your stomach.

One example breakfast:

  • Bagel with peanut butter

  • Banana

  • Two liquid nutrition drinks (such as Ensure)

  • Sports drink

For hot races, adding an egg with extra salt can be helpful.

Continue sipping fluids until approximately 30 minutes before the start.

Around 15-20 minutes before the gun:

  • Consume a gel if that’s part of your race plan.

  • Take a few sips of water.

Then stop eating and drinking and focus on the race.

Final Thoughts

The best carbohydrate-loading strategy is usually the simplest one.If your taper is appropriate, your glycogen stores are already moving in the right direction.

Focus on:

  • Resting well

  • Eating regularly

  • Increasing carbohydrates gradually

  • Reducing fiber

  • Choosing easy-to-digest foods

  • Staying hydrated

Don’t try to win the race at the dinner table. Show up rested, fueled, comfortable, and confident. That’s what successful carbohydrate loading is really about.

Racing, Planning, NutritionMarilyn Chychota