The International Society of Sports Nutrition position stand on nutrient timing recommends 8 to 12 grams of carbohydrate per kilogram of body weight per day to maximize glycogen stores, with the 10 to 12 g/kg end of that range commonly used for a 36 to 48 hour carb-loading protocol right before a race. This calculator uses that published range and a 10 g/kg midpoint as its default target.
Carb loading is eating a high-carbohydrate diet for the day or two before an endurance race so your muscles and liver store more glycogen than usual, a practice generally called glycogen supercompensation. More stored glycogen means more fuel available before you need race-day gels or sports drink to top it up.
Published protocols generally call for a 24 to 72 hour high-carbohydrate window before the race, with 36 to 48 hours the most commonly cited length in the sports-nutrition literature. This calculator lets you plan for either a 2-day or 3-day window.
Rice, pasta, bread, bananas and sports drinks are common carb-loading staples because they are carbohydrate-dense and easy to digest in quantity. The portion counts shown above use generic USDA-level average carb-per-serving figures, not a specific brand or recipe, so treat them as a rough estimate of scale rather than a precise meal plan.
A small, temporary weight gain is normal and expected: each gram of stored glycogen is held with roughly 3 to 4 grams of water, so a successfully loaded runner typically weighs slightly more on race morning. That water and glycogen is exactly the fuel and hydration reserve carb loading is meant to build.
No. The published guidance is a per-kilogram figure, so a heavier runner needs more total grams than a lighter one for the same relative glycogen benefit, which is why this calculator asks for your weight. Individual carbohydrate tolerance also varies, so sports-nutrition guidance recommends practicing a similar intake during training rather than trying a new volume of food for the first time on race week.