Carbohydrate loading, or "carb-loading," is one of the most common race preparation strategies for endurance athletes. Yet, many athletes get it wrong—either consuming too few carbs and running out of energy mid-race or overloading on the wrong foods, leading to digestive discomfort on race day.
In this guide, we’ll break down exactly how to carb-load effectively so you can show up to the start line fueled, hydrated, and ready to perform at your best.
Why Carb-Loading Matters
Carbohydrates are the body’s preferred energy source during endurance events. Your muscles store carbohydrates as glycogen, which serves as a readily available fuel source during prolonged activity. However, glycogen stores are limited. Without proper preparation, they can become depleted during long races, leading to fatigue and a drop in performance—commonly known as "hitting the wall" or "bonking."
Carb-loading maximizes glycogen stores so you have the energy needed to sustain your effort throughout the race. But simply eating a big pasta dinner the night before the race isn’t enough. Here’s how to do it properly.
The Right Way to Carb-Load
✅ Start 2-3 Days Before Race Day
A common mistake athletes make is cramming all their carbohydrate intake into one pre-race meal. Instead, you should begin gradually increasing your carbohydrate intake two to three days before the race. This extended approach allows your muscles to fully top off glycogen stores without causing bloating or GI distress.
Aim for 8-12 grams of carbohydrates per kilogram of body weight per day in the final 48-72 hours before the race. For example, if you weigh 70 kg (154 lbs), that means consuming 560-840 grams of carbohydrates per day. Spread your intake across meals and snacks to make it more manageable.
✅ Stick to Easily Digestible Carbs
Not all carbohydrates are created equal when it comes to carb-loading. The best choices are low-fiber, easily digestible carbs that provide fast-absorbing energy without overloading your digestive system. Some great options include:
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White rice
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Potatoes (white or sweet, without skin)
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Pasta (preferably white or whole wheat, depending on tolerance)
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Oatmeal
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Bread (white or whole wheat, depending on tolerance)
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Fruit juices or sports drinks
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Bananas
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Low-fiber cereals
The goal is to prioritize carbohydrates that your body can quickly convert into glycogen without causing bloating, gas, or stomach discomfort.
✅ Avoid Excessive Fiber, Fat, and Protein
Fiber, fat, and protein are all important in a well-balanced diet, but they can slow digestion and cause digestive issues when consumed in large amounts during carb-loading. To prevent bloating, gas, and sluggish digestion, reduce your intake of:
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High-fiber vegetables (broccoli, cauliflower, beans, lentils, etc.)
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Whole grains (opt for refined grains instead for better digestion pre-race)
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High-fat foods (fried foods, fatty meats, heavy sauces, nuts, and seeds)
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Excessive protein (focus on carbs instead, as protein won’t increase glycogen stores)
A meal that is high in fiber, fat, and protein will sit in your stomach longer and could leave you feeling heavy or bloated on race day. Keep your meals carb-focused and simple.
✅ Hydrate Properly
Carbohydrates store water, which is why hydration is a crucial part of effective carb-loading. For every gram of glycogen stored, your body retains about 3 grams of water. This means that as you increase your carbohydrate intake, you’ll also need to increase your fluid intake to support glycogen storage and prevent dehydration.
Tips for proper hydration while carb-loading:
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Drink water consistently throughout the day (not just right before bed or at meals).
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Include electrolytes (especially sodium) to help maintain fluid balance.
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Consider sports drinks, coconut water, or diluted fruit juice for added carbs and electrolytes.
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Avoid excessive caffeine or alcohol, as they can contribute to dehydration.
Sample Carb-Loading Meal Plan
Here’s a sample day of carb-loading for an athlete weighing 70 kg (~154 lbs) aiming for 700g of carbohydrates:
Breakfast:
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1.5 cups oatmeal with honey and banana (~120g carbs)
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1 glass sports drink (~25g carbs)
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2 slices white toast with jam (~60g carbs)
Snack:
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1 granola bar (~30g carbs)
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1 banana (~25g carbs)
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1 sports drink (~30g carbs)
Lunch:
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2 cups white rice with grilled chicken and teriyaki sauce (~150g carbs)
- 1 glass sports drink (~25g carbs)
Snack:
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1 bagel with honey (~60g carbs)
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1 sports drink (~30g carbs)
Dinner:
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2 cups pasta with light tomato sauce (~150g carbs)
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1 piece white bread (~30g carbs)
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1 glass apple juice (~30g carbs)
Pre-Bed Snack:
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1 cup low-fat vanilla yogurt with honey (~50g carbs)
This approach ensures a steady intake of carbohydrates spread throughout the day, preventing bloating while maximizing glycogen storage.
Common Carb-Loading Mistakes to Avoid
🚫 Waiting Until the Night Before to Start – A single pasta dinner won’t fully replenish glycogen stores. Start at least 2-3 days in advance.
🚫 Overloading on Fiber and Fat – Stick to low-fiber, easily digestible carbs and limit fatty foods to avoid digestive discomfort.
🚫 Ignoring Hydration – Remember that carbohydrates store water, so proper hydration is key to effective carb-loading.
🚫 Eating Too Much or Too Little – Follow 8-12g of carbs per kg of body weight per day. Too little leads to early fatigue; too much can cause bloating.
🚫 Trying New Foods – Stick to familiar foods that your body tolerates well to avoid unexpected GI issues on race day.
The Final 24 Hours Before the Race
The day before the race, continue eating high-carb meals, but start scaling back portion sizes slightly to avoid feeling overly full. Stick to bland, low-fiber, and low-fat foods.
On race morning, eat a high-carb breakfast 2-3 hours before the start. Good options include white toast with honey, oatmeal with banana, or a bagel with jam. Keep it simple and stick with what you know works for you.
Conclusion
Carb-loading is a science, and when done correctly, it can significantly improve your endurance and race performance. By gradually increasing your carb intake 2-3 days before the race, choosing easily digestible carbs, avoiding excessive fiber, fat, and protein, and staying properly hydrated, you’ll maximize glycogen stores without unwanted digestive issues.
Follow these tips, avoid common mistakes, and you’ll be well-fueled to crush your race. Happy racing! 🏃♂️🚴♀️🏊♂️
