Review of Carb Loading Strategies Before a Race

For decades, runners preparing for a marathon or ultra have sworn by carb loading — eating large amounts of carbohydrate in the days before the race to maximize energy stores. But with so many variations on the strategy, from pasta parties to scientific glycogen-depletion protocols, what really works?

What Is Carb Loading?

Carb loading is the practice of increasing carbohydrate intake to super-saturate muscles with glycogen, the stored form of glucose. Since glycogen is the primary fuel source for endurance running, having more stored energy can delay fatigue and prevent “hitting the wall.”

Common Strategies

Classic Carb Loading (3–7 days): Runners taper training while gradually increasing carbs to 70–75% of total calories.
Modified Taper (2–3 days): Higher carb intake combined with reduced training volume.
Old-School Depletion Method: Deplete glycogen through hard training, then refuel. Effective, but risky and outdated.

Benefits

Improved Endurance: More glycogen means sustained energy.
Delayed Fatigue: Helps runners push through late-race miles.
Proven by Research: Decades of studies support glycogen supercompensation.

Drawbacks

Digestive Discomfort: Overeating carbs can cause bloating, gas, or GI distress.
Weight Gain: Each gram of glycogen stores with water, leading to a temporary 2–4 pound increase.
Individual Response: Not all runners feel benefits, especially in shorter races.

Best Practices

Focus on familiar foods to avoid stomach upset.
Spread carbs evenly across meals.
Stick with moderate fiber intake.
For marathons and ultras, aim for ~8–10 g carbs per kg body weight per day in the final 2–3 days.

Verdict

Carb loading works, but it doesn’t require a pasta binge the night before your race. A gradual, balanced approach in the final days is the safest and most effective method. For half marathons or shorter, it may not be necessary.

- Edward

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