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Carb loading without the bloat: a 3-day plan

How much carbohydrate you actually need before a half or full marathon, and what to eat.

DL Daniel Lee · Sep 28, 2026 · 6 min read

Carb loading has a reputation for one giant bowl of pasta the night before a race. In practice that is the least effective way to do it. Your muscles store glycogen gradually, and a huge late dinner mostly leads to a heavy stomach on the start line.

Who needs it

For races under about 90 minutes your normal diet is usually enough. For a half marathon run slower than that, and for every marathon, topping up glycogen over the last two to three days makes a measurable difference in the final third of the race.

How much

A common target is 7–10 g of carbohydrate per kilogram of body weight per day for the final 36–48 hours. For a 65 kg runner that is roughly 450–650 g a day — far more than most people eat, which is why it has to be planned.

DayFocusExample
Race −3Normal meals, slightly more starchOats with honey, rice bowl, potatoes with dinner
Race −2Main loading day, lower fibreBagels, white rice, juice, rice cakes with jam
Race −1Keep loading, lighter dinnerPancakes, plain pasta at lunch, early simple dinner
Race dayBreakfast 3 hours beforeWhite toast with jam, banana, coffee if you usually drink it

Avoiding the bloat

  • Drop high-fibre foods (beans, bran, big salads) for the last 48 hours.
  • Use liquid carbs — juice, sports drink, flavoured milk — to hit numbers without volume.
  • Spread intake over 5–6 smaller meals instead of three big ones.
  • Expect to gain 1–2 kg. That is water stored with glycogen, and you will need it.

Practise the plan once before a long training run. Race week is not the time to discover which foods disagree with you.

General information for healthy adults, not medical advice. See our disclaimer.

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