The Correct Way to Carb-Load for Cycling: A Pre-Race Carbohydrate Supercompensation Guide

Introduction

“Eating more rice before a race” is the instinct of many Taiwanese cyclists, but the science of carb-loading is far more complex than “having a big meal.” Done correctly, it can raise muscle glycogen stores from the normal 300–400g to 500–600g, extending high-intensity riding time by 20–30%; but done incorrectly, it is not only ineffective—it can also cause gastrointestinal discomfort and water retention, ultimately hurting race performance.

The Science Behind Carb-Loading

The Storage Limit of Muscle Glycogen

The capacity of human muscle to store glycogen is not fixed—it can be “trained” to expand:

• Normal non-athletes: approximately 300g (1,200 kcal)
• Endurance athletes in training: 400–500g (1,600–2,000 kcal)
• After carb-loading: 500–600g (2,000–2,400 kcal)

Each gram of muscle glycogen is stored with approximately 3 grams of water, so body weight will increase by 1–2 kg after carb-loading (mostly water)—this is a normal phenomenon, not fat gain.

Performance Benefits of Carb-Loading

A systematic review by Jeukendrup & Gleeson (2010) shows:

• In exercise lasting more than 90 minutes, carb-loading can improve performance by approximately 2–3%
• Primary mechanism: delaying the point of glycogen depletion, sustaining the duration of high-intensity output
• For events shorter than 60 minutes: the benefit is not significant (because glycogen is not the primary limiting factor)

Modern Carb-Loading Protocols

Protocol 1: The 3-Day Protocol (Currently Most Common)

Example for a 70 kg rider: 2 days before the race, consume 560–700g of carbohydrates per day (approximately 2,240–2,800 kcal from carbohydrates)

Protocol 2: 1-Day Rapid Loading (24 Hours Before Race)

For riders who cannot follow the full 3-day protocol, research shows that just 24 hours of a high-carbohydrate diet (10–12 g/kg), combined with a final “depletion ride” (a short, high-intensity training session 3 days before the race to empty glycogen stores), can also achieve effective loading.

Protocol 3: Race-Eve Dinner as the Core (Practical Version)

A simplified version adopted by many Taiwanese cyclists:

• 2 days before race: normal training, normal diet
• 1 day before race: high-carbohydrate dinner (3–4 bowls of white rice, noodles, or sweet potato)
• Race morning: light snack 2–4 hours before the start

Effect: Although not as comprehensive as the standard protocol, it can still increase glycogen stores by 10–15% compared to a “normal diet.”

Practical Race-Day Nutrition

Race Morning Breakfast (2–4 Hours Before Start)

• Goal: Replenish liver glycogen depleted overnight without leaving the stomach overly full
• Recommended foods: Plain rice porridge + light side dishes, white toast + jam, banana + oatmeal
• Carbohydrate amount: 1–2 g/kg (70 kg = 70–140g)
• Avoid: High-fiber, high-fat, high-protein foods (they slow digestion and increase gastrointestinal burden)

30–60 Minutes Before the Start

• 100–150 ml of electrolyte drink or energy gel (20–30g carbohydrates)
• Avoid large amounts of solid food (gastrointestinal stress)

Common Mistakes and How to Avoid Them

Mistake 1: Not Training Regularly, Then Carb-Loading Only Before the Race

The “tank” for muscle glycogen storage needs training to expand. Untrained individuals have a very low ceiling for glycogen supercompensation, and excess carbohydrates will only be converted to liver glycogen or body fat. Solution: Carb-loading is only effective for riders who train consistently.

Mistake 2: Consuming Large Amounts of Fat at the Same Time

Many Taiwanese dishes (braised pork rice, minced pork noodles) are simultaneously high in both carbohydrates and fat, which slows carbohydrate absorption and causes gastrointestinal discomfort during the race. Solution: During the loading period, choose low-fat, high-carbohydrate foods.

Mistake 3: Neglecting Hydration

Each gram of glycogen binds approximately 3 grams of water during storage, so carb-loading requires simultaneous fluid intake (increase by 500–1,000 ml per day); otherwise, glycogen storage is limited.

Mistake 4: Binge Eating the Day Before

Suddenly consuming large amounts of food can cause gastrointestinal discomfort and reduced sleep quality, ultimately hurting race readiness. Solution: Consume carbohydrates in multiple small portions spread throughout the day.

Carb-Loading Strategies with Local Taiwanese Foods

Practical Recommendations

• Test during training: Do not do your first carb-loading for your most important race; first test your gastrointestinal response in a training event
• Individualize adjustments: Some riders have sensitive gastrointestinal systems on high-carbohydrate diets (bloating, frequent bathroom trips) and need to find their own upper limit of carbohydrate intake
• Consider event type: Carb-loading provides the greatest benefit for climbing races lasting over 3 hours (such as the Wuling eastbound route); the benefit is limited for events lasting 1–2 hours

Conclusion

Carb-loading is a pre-race strategy that is simple yet requires precise execution. Understanding its scientific basis, choosing foods suited to Taiwanese dietary culture, and testing repeatedly during training will allow you to stand at the starting line on race day with full glycogen reserves.

Related Reading

• Carb-Loading Three Days Before the Race: Complete Plan and Practical Example
• Carbohydrate Loading: What to Eat Before the Race
• Marathon Pre-Race Carb-Loading: A Practical 3-Day High-Carbohydrate Meal Plan
• The Science of High-Carbohydrate Loading: Optimizing for Marathons and Long-Distance Riding