Tips to Live By

Does Carb Loading Really Work? (& More Race Training Nutrition Questions, Answered)

Oct. 4, 2023 - Katie McCallum

There's a lot to think about when training for a race.

Getting the right gear. Following a training plan that reduces the chance of both undertraining and overtraining. Making sure you're not just running, since cross-training is important for reducing the injury risk. Logistical questions pop up along the way, too, like whether you should train while sick.

The list goes on and on. But amid all the planning, don't forget one of the most critical considerations for endurance running: how to properly fuel your body.

Whether you're a veteran runner or training for your first race, nutrition is key to helping you log the miles and prepare for the big day. But it can also get complicated, and you likely have some questions about the right way to think about your diet. Monica Bearden, a registered dietitian and sports nutrition consultant at Houston Methodist, is here to provide answers.

Does carb loading work?

As a runner, you hear about carb loading so much that you might wonder whether it's more hype than help. But Bearden reaffirms that this tried-and-true advice checks out.

"Yes, tapering workouts and increasing carbohydrate intake 1-3 days before a race helps to maximize muscle glycogen, which is the form of energy stored in muscles," explains Bearden. "During the race, your muscles will turn to this muscle glycogen to sustain effort and performance after the carbohydrates from your pre-exercise snack or meal run out."

What are the best foods to eat before running?

Similar to carb loading before a race but without the training tapering, eating plenty of carbohydrates the day before a long training run is also recommended. This helps ensure that muscles have plenty of energy stored away.

"About 1-2 hours before that run, you'll also want to be sure to take in some carbohydrates — ideally refined (or fast) carbs, since they're easy to digest," says Bearden. "This helps save muscle glycogen for those later miles, helping provide you with energy to finish strong."

If you're planning to be running longer than an hour, it's also important to bring carbs with you. Bearden recommends carbohydrate- and electrolyte-containing drinks, like a full sugar sports drink, for this purpose.

What should a runner's diet plan look like?

Knowing how to properly fuel before a long run is critical, but don't forget that what you eat between your workouts matters, too.

"Recovery after exercise and the days before a long run are extremely important, and nutrition plays a huge role in that," says Bearden. "The American Academy of Sports Medicine and the Academy of Nutrition and Dietetics have guidelines for endurance runners to follow."

Bearden says that the guidelines can be overwhelming for most people, as can figuring out the best ways to implement them. It's why she recommends consulting a sports dietitian to understand your specific needs and help plan meals that can improve your recovery and performance.

The high-level recommendations to get anyone started include:

  • Meals between workouts should be nutritious and well-balanced, prioritizing lean proteins, whole grains, fruits, vegetables and low-fat dairy.
  • Aim to eat at least 5-7 grams of carbohydrates per kilogram of body weight per day when actively training.
  • About 1-2 hours before a training run, consume 1-2 grams of easily digestible carbohydrates per kilogram of body weight.
  • Within the hour after a long training run, eat 1.5 grams of carbohydrates per kilogram of body weight and 15-30 grams of protein.

What supplements should a runner take?

Your body is working harder than usual while training for a race, so you might wonder whether it needs extra oomph to provide a boost. Perhaps you've heard that vitamins like B12 and minerals like zinc and magnesium are particularly important for runners.

"So long as you're eating a well-balanced diet with enough calories from animal protein sources and plant-based foods, you should be getting all the nutrients, vitamins and minerals you need to support energy production, muscle maintenance, bone and joint health and more," says Bearden.

She adds that taking a multi-vitamin to help ensure your body has what it needs isn't a bad idea, so long as you're choosing one that contains reasonable amounts of vitamins and minerals (around 100% daily values). Runners don't need individual supplements of specific vitamins and minerals unless they have a known deficiency.

As for "performance enhancing" products like pre-workout supplements, Bearden says they're worth a whole discussion themselves. These supplements can help power a workout, but they can also come with risks, as some act mainly as a stimulant. If you plan to take a pre-workout supplement, it's always best to first check with your doctor and, as mentioned, select a supplement that's been tested by a third party and is certified by an independent, third-party laboratory, such as NSF.

Are there certain foods to avoid before a long run?

You've likely heard of the dreaded stomach troubles that can sometimes arise when running long distances. Fortunately, there are ways to avoid them.

"Foods that are high in fiber, fat and even protein can cause gastrointestinal issues during exercise if consumed too close to a workout," explains Bearden. "This is why we instead recommend refined, easily digestible carbohydrates before a long run."

Examples of easy-to-digest carbs to eat before a long training run include:

  • A banana or raisins
  • Pretzels or graham crackers
  • English muffin with jelly or honey


(Related: 5 Tips for Avoiding Gastrointestinal Distress on Race Day)

When should you carry water and electrolytes on a training run?

For something as simple as drinking water, hydration can sure get complicated. Should you always carry water with you on a run? When should you consider adding electrolytes to it?

The answer is: It depends, based on how long you plan to run, the temperature (as well as humidity) and how much you sweat.

Generally speaking, it's important to start every run well hydrated. And, no, this doesn't mean slamming several glasses of water before your run once you realize you haven't had much to drink yet today — though it is helpful to drink a glass of water beforehand. Starting your run well hydrated means drinking water throughout the day. You can check on your hydration status by monitoring the color of your urine. The darker it is, the less hydrated you are.

You'll want to start thinking about carrying water with you on any run that lasts longer than an hour, though the weather and how much you sweat can shorten that time frame. Since you lose water and electrolytes through your sweat, it's important to replace both if you're sweating a lot.

"In the summer months in Houston, any outdoor exercise lasting 30 minutes or more should include water with electrolytes," says Bearden. "If you're a heavy sweater, even just 15 minutes of exercise in the heat of the day may warrant an electrolyte drink."

(Related: How to Stay Hydrated While Running in the Heat)

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Categories: Tips to Live By