Carb Loading for Endurance: How to Do It Right

Carb loading is the practice of increasing carbohydrate intake in the days before a long endurance event to maximize muscle and liver glycogen stores. It's most beneficial for races lasting around 90 minutes or longer, like the marathon. Done correctly — emphasizing familiar carbs over several days rather than one giant pasta dinner — it helps you run strong and delay the wall.

Who needs to carb load

Carb loading matters for events where glycogen depletion is a real risk — marathons, ultras, long triathlons, and other efforts beyond about 90 minutes. For a 5K or 10K, it's unnecessary; your normal glycogen stores easily cover those distances. Match the strategy to the demand of your race.

How to carb load properly

1. Start 1–3 days before the race, not just the night before.
2. Increase the proportion of carbohydrate in your meals (aim high, e.g., 8–10g per kg of body weight on the key day).
3. Choose easy-to-digest carbs: rice, pasta, bread, potatoes, fruit.
4. Reduce fat and fiber to make room and avoid GI distress.
5. Keep portions manageable across several meals rather than one feast.

Common carb-loading mistakes

• Eating one enormous pasta dinner the night before — too late and too much at once.
• Adding lots of fat (creamy sauces, cheese) instead of pure carbohydrate.
• Overeating fiber, which can cause race-morning stomach trouble.
• Trying unfamiliar foods that upset your stomach.
• Mistaking water-weight gain from stored glycogen for fat gain — it's normal and helpful.

Don't forget race morning

Carb loading sets up your stores, but a familiar carb-rich breakfast 2–3 hours before the start tops off your liver glycogen after the overnight fast. Combine a few days of loading with a tested pre-race breakfast and in-race fueling for the complete picture.