Carb Loading

Filling the tank before a race

Your body stores carbohydrate in muscle. Those stores last one to two hours of hard effort — after that it gets tough.

Carb loading means eating more carbohydrate than usual in the days before a race so the stores are full. The calculator tells you what that means for your body weight.

How it is calculated

Carbohydrate per day = body weight × grams per kilogram. The factor depends on race duration: under 2.5 h 8 g/kg for 2 days, from 2.5 h 10 g/kg for 2 days, from 4 h 12 g/kg for 3 days.

Muscles store at most about 500 g of glycogen; at roughly 10 g/kg over two days they are full — extra days or extra grams beyond that add nothing but weight.

Example: 70 kg, race lasting 3:30 h. 70 × 10 = 700 g of carbohydrate per day, on the two days before the start.

The food examples convert the daily amount into rice or pasta (50 %), sports drink (20 %), bananas and bars (15 % each) — as an order of magnitude, not a meal plan.

When you calculate carb loading, expect the scale to move: every gram of glycogen binds about 3 g of water, so 1 to 2 kg more on race morning is normal.

When it is worth it

From around ninety minutes of racing. For a 5K or a sprint triathlon it does nothing — normal stores are more than enough.

The old method with days of depletion first is outdated. Two to three days of extra carbohydrate and light training is enough today.

Frequently asked questions

Will I gain weight?

Short term you gain one or two kilos, because the body stores water alongside the carbohydrate. That is intended and disappears after the race.

What should I actually eat?

Familiar, easily digested food: rice, pasta, bread, potatoes, bananas. Reduce high-fibre foods, which burden the gut.

And on race morning?

A light, carbohydrate-rich meal two to three hours before. Nothing new, nothing fatty, nothing very high in fibre.