How to carb load for a half or full marathon

It’s two days of eating, not one pasta dinner. · 2 min read · Updated September 30, 2026

In short: Real carb loading is 36–48 hours of 10–12 g of carbs per kg of body weight, for races over about 90 minutes. Here’s what that means for your weight, what to eat, and when to skip it.

How we made this guide: we built it from the research below and checked every number against it: ACSM, Academy of Nutrition and Dietetics & Dietitians of Canada joint position stand (2016).

The big pasta dinner the night before a race is a nice ritual. It isn’t carb loading, though. Your muscles store carbohydrate as glycogen, and topping them all the way up takes more carbs over a longer window than one meal can deliver.

What the guidelines say

The joint position stand from the American College of Sports Medicine, the Academy of Nutrition and Dietetics and Dietitians of Canada (Thomas, Erdman & Burke, 2016) sets carb loading at 10–12 g of carbohydrate per kg of body weight per day, for 36–48 hours, before events that last longer than about 90 minutes of sustained effort.

What that means for your weight

Body weight	Carbs per day, for the last 2 days
110 lb (50 kg)	500–600 g
130 lb (59 kg)	590–710 g
150 lb (68 kg)	680–820 g
170 lb (77 kg)	770–930 g
190 lb (86 kg)	860–1030 g

Calculated from 10–12 g/kg. A big restaurant plate of pasta is often around 100–150 g of carbs. A real load is several times that, two days in a row.

What one loading day looks like (130 lb runner, ~600 g)

A worked example for the 130 lb row, using simple foods at normal mealtimes. Carb numbers are approximate, from food labels and USDA FoodData Central.

When	What	Carbs
Breakfast	a large bagel with 2 tbsp jam, a banana, 12 oz orange juice	~152 g
Mid-morning	a cup of applesauce and a small box of raisins	~60 g
Lunch	2 cups cooked white rice with grilled chicken, and a banana	~116 g
Afternoon	2 slices white toast with 2 tbsp honey	~63 g
Dinner	3½ cups cooked pasta with 1 cup tomato sauce	~150 g
Evening	3 Medjool dates and a cup of milk	~67 g
Total		~608 g

Repeat something like it on both days. A few things that make it easier:

Lower fiber for those two days. Many sports dietitians suggest white rice, white bread and peeled potatoes over whole grains, so the volume sits easier in your stomach. The banana, raisins and dates above add fiber; if you’re keeping it low, swap them for juice or applesauce (see carb load snacks).
Drink some of it. Juice and milk add carbs without much bulk.
Stick to foods you already know. Race week isn’t the time to try new ones.

If your race is under about 90 minutes

You don’t need to carb load. For shorter races the same guidelines suggest a normal, carbohydrate-rich day beforehand is enough: carbs at every meal the day before, and a familiar breakfast on race morning.

The part most runners skip: writing it down

The most useful carb-loading plan is the one that already worked for you. Note what you ate in the two days before your best long run, and repeat it before the race. We built My Track Record so logging a meal is one spoken sentence, which makes keeping that record realistic through a training block.

Track your training and fueling in one sentence.
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By Andrew, founder of My Track Record. Andrew has been active all of his life across a variety of sports and continues to stay active through climbing, swimming, weight training, golfing, snowboarding, and more. He built My Track Record so logging food and training takes one spoken sentence and can support any activity. He puts these guides together from published sports science research cited on each page. About Andrew

Sources

Thomas DT, Erdman KA, Burke LM. Nutrition and Athletic Performance: joint position statement of the American College of Sports Medicine, the Academy of Nutrition and Dietetics and Dietitians of Canada. Med Sci Sports Exerc. 2016;48(3):543–568. Source

General information for healthy adult runners, not medical advice. If you have a medical condition, are pregnant, or have a history of disordered eating, talk to a doctor or registered dietitian before changing how you eat or use caffeine.