Carb-Loading Myths vs. Reality: Real Nutrition for Distance Runners

A big pasta dinner is not a complete marathon fueling plan. What you eat before that dinner, on race morning, and during the race matters too.

For runners preparing for the Austin Marathon, carb-loading can be useful. But it has a specific purpose, and eating until you are uncomfortable is not part of it.

What is carb-loading?

Carb-loading means increasing carbohydrate intake while reducing training before a long endurance event to maximize the glycogen stored in your muscles. It is most useful for sustained efforts lasting longer than about 90 minutes.

Glycogen is stored carbohydrate that your muscles use for fuel. Starting with more of it can help delay fatigue, but it does not replace race-morning breakfast or carbohydrates consumed during the race.

Myth 1: You can do all your carb-loading at dinner

Reality: A planned day or two of carbohydrate-rich meals is more useful than one oversized meal.

A commonly recommended full-loading protocol is 10 to 12 grams of carbohydrate per kilogram of body weight per day for 36 to 48 hours before competition, alongside reduced training. This is an event-specific approach to maximizing glycogen, not an everyday target or a requirement before every long run.

For context, a runner weighing 70 kilograms, about 154 pounds, would consume 700 to 840 grams of carbohydrate daily under that protocol. Those are grams of carbohydrate, not grams of food.

That substantial amount takes planning. Spread intake across meals and snacks rather than saving it for dinner. A registered sports dietitian can help determine whether this approach fits your event and translate it into manageable portions.

Source: Gatorade Sports Science Institute’s carbohydrate guidance.

Myth 2: Every runner needs to carb-load before every run

Reality: Fuel for the effort you are about to do.

A short, easy run and a marathon do not require the same preparation. Formal carb-loading is generally unnecessary for efforts shorter than about 90 minutes when you are already eating enough to support training.

Duration matters more than the distance printed on your registration. A half marathon completed in two hours presents different fueling demands from one completed in 75 minutes.

Your runner nutrition plan should support regular training first. Race-week carb-loading is an addition to that foundation, not a way to make up for weeks of inadequate fueling.

Myth 3: Healthy carbs for runners must always be high in fiber

Reality: A food that works well at lunch may not work as well just before running.

Oats, whole-grain bread, beans, fruit, and starchy vegetables can all contribute carbohydrates and other nutrients to your everyday meals.

Before a race, lower-fiber choices may be more comfortable for runners prone to digestive trouble. White rice, regular pasta, plain bagels, and peeled potatoes are practical options. You do not need to abandon fiber throughout training to use these foods around a race.

When choosing healthy carbs for runners, consider timing as well as nutrition. The goal is to meet your fuel needs with foods you tolerate, not to make every pre-run meal as high in fiber as possible.

Myth 4: Carb-loading means you can skip breakfast

Reality: Breakfast still has a job to do.

Liver glycogen decreases overnight as your body maintains blood glucose. A carbohydrate-rich breakfast helps replenish that supply before exercise.

General guidance recommends 1 to 4 grams of carbohydrate per kilogram of body weight in the 1 to 4 hours before exercise. That broad range is a planning framework, not an instruction to eat the maximum. Your timing, event demands, and digestive tolerance should guide the amount.

The Gatorade Sports Science Institute explains the distinction between pre-event loading and pre-exercise fueling.

What should you eat before a long run?

Choose familiar, carbohydrate-rich foods in an amount you can comfortably digest before starting. Reduce fat and fiber near the run if they tend to cause stomach trouble.

With a few hours available, options include a plain bagel with jam and a banana, toast with honey, or oatmeal if you tolerate it well. With less time, a smaller snack such as applesauce or toast with jam may be easier to manage.

These are food ideas, not equivalent portions. Use training runs to find the amount and timing that work for you.

Traveling to Austin for race weekend? Plan how you will get and prepare your usual breakfast. Race morning is a poor time to discover that your hotel has no microwave or that breakfast service starts after you need to leave.

Myth 5: A good carb load means you will not need gels or other fuel

Reality: Stored carbohydrate is limited, even after loading.

The Australian Institute of Sport recommends 30 to 60 grams of carbohydrate per hour for endurance exercise lasting about 1 to 2.5 hours. For prolonged efforts exceeding roughly 2.5 to 3 hours, up to 90 grams per hour may be useful when practiced and tolerated.

Higher intakes generally call for a mix of carbohydrate sources, such as glucose and fructose. Do not jump to a higher target for the first time on race day.

For example, two gels containing 25 grams of carbohydrate each provide 50 grams total. Carbohydrates from a sports drink also count toward your hourly intake. An electrolyte drink may contain little or no carbohydrate, so read the label rather than assuming it provides fuel.

Follow your gel’s directions for water and test the combination during training. The Australian Institute of Sport’s gel guidance covers both fueling targets and digestive tolerance.

How to practice your Austin Marathon fueling plan

Use an upcoming long run to rehearse the parts you can control.

Prepare your breakfast beforehand. Record what you eat, how much, and how long before running.
Check your fuel labels. Calculate the carbohydrates in the gels, chews, or drinks you plan to use.
Practice your timing. Follow a schedule you have tested rather than waiting until you feel depleted.
Record what happened. Note energy, hunger, and stomach comfort so you can make specific adjustments.
Confirm race logistics. Review the current official race information before relying on on-course products, and plan what you need to carry.

For additional meal ideas, read the Austin Marathon’s pre- and post-race nutrition tips from an H-E-B dietitian.

Carb-loading FAQs

Is rice better than pasta for carb-loading?

Neither is automatically better. Both provide carbohydrates. Choose the food and preparation you tolerate well, then plan portions around your needs.

Can carb-loading temporarily increase your weight?

Yes. Glycogen is stored with water, so increasing glycogen stores can raise body weight temporarily. That change does not automatically represent body-fat gain. This relationship is discussed in the Gatorade Sports Science Institute’s carbohydrate review.

Does carb-loading guarantee you will avoid hitting the wall?

No. It can help delay fatigue related to depleted glycogen, but race performance also depends on training, pacing, during-race fueling, and conditions.

Make fueling part of your training

Before your next long run, decide what you will eat beforehand and what fuel you will take with you. Afterward, write down what worked.

That gives you something more useful than a last-minute pasta strategy: a plan you have already tested before the Austin Marathon.

This article provides general nutrition education, not individualized advice. Consult a registered sports dietitian for a personalized plan, especially if you have diabetes, persistent digestive symptoms, or other medical nutrition needs.