What to Eat During a Race

Your in-race strategy is to keep your tank from sputtering to zero. The two-pronged focus for most athletes is on carbohydrates and hydration.

The exact amount, form, and timing of carbs and hydration will be unique to you, and it may take a fair amount of trial and error to ascertain those details. Still, there are general guidelines to help you determine what works best. These are largely based on how long and how hard you’re working.

The exact amount, form, and timing of carbs and hydration will be unique to you, and it may take a fair amount of trial and error to ascertain those details.

“Time and intensity dictate the fuel,” says Thomson. “For example, if you and I did five minutes of extremely hard effort, we would essentially fire the same substrate. But if we ran a marathon, my time might be three hours and five minutes, and yours might be longer or shorter, impacting our [nutrition] needs.”

Top Off the Carbs

Nailing the right amount of energy is a Goldilocks affair. Inadequate carbohydrate intake can lead to glycogen depletion, which occurs when your body runs out of sugar to burn. Many endurance athletes are familiar with this phenomenon, often called “bonking” or “hitting the wall”: The lack of fuel causes fogginess and extreme fatigue and typically leads to compromised performance.

When you hit the wall, it’s not just your muscles that run out of fuel. Your brain, too, runs on glucose and requires a steady supply for proper functioning. Without that supply, you may experience brain fog and loss of coordination and other cognitive skills, says Myles Spar, MD, an expert in ­personalized performance medicine and national director and vice president of medical services at AndHealth.

Glycogen depletion can also lead to digestive upset and impaired recovery after an event. In rare cases, it can cause exertional rhabdomyolysis — a potentially fatal condition in which muscle fibers break down and toxic compounds enter the bloodstream.

Overfueling can also cause problems, notably digestive distress: Excess sugar stimulates the gut to release water and electrolytes, which can loosen bowel movements. Other signs that you’ve ingested too much include lethargy, stomachache, cramping, and vomiting.

The optimal carbohydrate intake ranges from 40 to 90 grams per hour, says Thomson, but this can depend on the length of the event:

• For endurance efforts of 60 to 150 minutes, you may want to stick to the lower end of this range and ingest 40 to 60 grams of carbs per hour.
• For longer endurance or ultra­endurance efforts lasting four to six hours or more, you may benefit from edging closer to 90 grams of carbs per hour. (It may take rigorous training to ingest more than 90 grams per hour, explains Blow, who notes that this approach isn’t necessary for most exercisers.)

Again, finding the right range and timing for you requires practice. Take advantage of your training to determine what works best for you. You might find that 80 grams per hour is your sweet spot but only when divided into 40-gram increments every half hour.

Your experiment should include liquid carbs, solid carbs, and gels. They are all good options — and you can mix and match these as desired and tolerated.

A small banana, for instance, contains about 23 grams of carbs — about the same as a serving of many sports gels and chews. Sports-drink mixes can support hydration and replenish energy stores; super-high-carb mixes can provide as much as 100 grams of easy-to-digest carbohydrates.

In general, Spar recommends trying to avoid carb sources containing high-fructose corn syrup and artificial flavors, preservatives, and dyes.

Maintain Fluid Intake

“Hydration is about much more than water intake,” McKinney says. Your needs will depend on numerous factors. These include temperature, humidity, and altitude; your stress levels; and how well hydrated you were when you woke up on the day of your event, among others.

If you sufficiently hydrate prior to your event and anticipate a lower-­intensity effort or one lasting less than 90 minutes, you might only need to sip small amounts of an electrolyte drink. Blow notes that elite athletes competing in high-intensity aerobic events have benefited from rinsing their mouths with a carb-containing electrolyte drink and spitting it out. You can experiment with these methods during training.

Sweat loss can become more significant between 90 minutes and two hours into a race, making it important to rehydrate. As a general target, McKinney recommends drinking about 16 ounces of water with electrolytes per hour of physical activity. This helps replenish the minerals lost through sweating. Some elite athletes choose to measure their sweat rate and adjust their intake to account for sweat loss, she says. (Blow has instructions for testing this here.)

Drinking too much water is less common than drinking too little, but the consequences of extreme overhydration can be as dangerous as those associated with dehydration. Overhydration can dilute sodium levels in the blood, which can cause hyponatremia (an electrolyte imbalance) and water intoxication (a rare phenomenon that occurs when water intake exceeds the amount of ­water excreted by the kidneys).

For athletes who exercise for hours or even days on end, maintaining a precise blood chemistry can be extremely important. Look for ­electrolyte products containing sodium, potassium, phosphorous, calcium, and magnesium to make the most of every sip. (Learn more about the importance of electrolytes on page “How Electrolytes Can Boost Your Athletic Performance” and at “Everything You Need to Know About Hydration.”)

Consider Proteins and Fats

By the time you start your event, protein and fat will likely take a back seat to carbs — at least until the race is over. That’s because fat and protein take longer to digest, says Koff. They offer less potential as a quick fuel source and they may cause digestive distress.

But that doesn’t mean you should completely avoid either macronutrient. Test out what works best for your body several times before the actual race or event day.

Protein can help minimize potential muscle damage, a normal consequence of prolonged, intense activity. The International Society of Sports Nutrition recommends consuming about 0.25 grams of protein per kilogram of body weight — about 0.11 grams per pound — per hour of intense endurance exercise when taken along with carbohydrates. For a 160-pound individual, that’s almost 18 grams of protein, roughly equivalent to three large eggs or ¾ cup of Greek yogurt.

For more convenient options, look for — or make your own — bars, gels, or chews that contain protein. (Steer clear of additives, like sugar alcohols, to ensure digestibility.) Plant-based athletes can find options containing protein sources such as chia seeds, nuts, and pea protein. (For more on fuel for plant-based athletes, see “The Plant-Powered Athlete.”)

If you carry a hydration pack, you can mix in protein or amino-acid powders, which offer the muscle-­protective properties of protein alongside water, electrolytes, and carbs. Clear protein powders are a good option if a thick shake is unappetizing or difficult to transport.

Unlike protein, fat doesn’t offer much benefit during an endurance event. “Fat doesn’t turn over into fuel well in the middle of a workout, and, ultimately, it may slow digestion and could cause GI issues,” Thomson says.

Think of fat as an incidental part of fuel, and pick something that you tolerate well. This might include relatively small amounts of fat in, say, dates stuffed with a bit of nut butter or a pat of butter on some sweet potato. Again, spread with a light hand and practice ingesting it during training.

Practice Makes Perfect

It can’t be overemphasized: Make intra-event fueling part of your training. “It’s important to train like you race and race like you train,” Thomson insists.

The number of training sessions needed to ensure a successful approach varies. One study on endurance runners, published in Applied Physiology, Nutrition, and Metabolism, found that two weeks of gut training resulted in improved gastrointestinal symptoms.

Other studies and experts say a gut-training protocol takes four to 10 weeks. “I recommend taking at least a month to adapt to nutrition changes,” says Spar.

During each training session, pay attention to your body’s signals to adjust what, how much, and when you eat. Feeling lightheaded or dizzy can signal dehydration, Spar notes. Craving salt can be an early sign that you’re running low on sodium. Stomach pain and muscle cramps are reliable indications of low electrolytes.

And feeling a lack of energy could be a sign of carbohydrate deficiency. If you crave sugar immediately after a workout, you likely didn’t eat enough carbs before or during your routine.

Learn from your missteps and your successes. Take note of what works for you and rehearse that winning recipe. By race day, you’ll be optimally fueled and ready to go.