Some runners swear by fasted cardio. Others refuse to run without having a meal prior. Still others rely on energy gels to maintain performance. The truth, though, is that everyone is right and no one is right. The best running fuel differs significantly depending on the athlete, the type of run, the run distance, run intensity, and weather conditions. 

Credit: Maridav / Shutterstock

In this guide, registered dietitians Daniel Chavez at Fay Nutrition and Jena Brown at Victorem explain the finer details of running fuel and how to ensure you take in the right fuel—and the right amount of it—before, during, and after your runs so you can avoid the dreaded “bonk.

How to Fuel Your Run

When you think about fueling for your run, you may only think about what you should eat before you head out. However, running fuel also includes intra-workout calories if necessary, plus post-workout refueling to ensure you start your next session off on the right foot. 

Carbohydrate Needs

Most importantly, runners should consider carbohydrate intake over other macronutrients, Brown says, because “Carbohydrates before a run provide fuel as blood glucose and carbohydrate stored in your muscles as glycogen.” (1)

[Read More: The Best Healthy Carbs to Add to Your Meal Prep Plans]

How many carbs you need before a run depends on how long before your run you plan to eat, as well as your body weight. She outlines carb needs as follows: 

Eating 2 to 3 hours before you run: 0.9 to 1.4 grams of carbohydrate per kilogram of body weight 

Eating 1 hour before you run: 0.5 grams of carbohydrate per kilogram of body weight

Eating 15 to 30 minutes before you run: 15 to 30 grams of carbohydrates as a general guideline

Protein Needs

Advice about the weight room almost always includes something about protein—always more protein. But running tips rarely feature this macro, so runners may neglect protein intake. 

It’s common to think that protein is only important for strength athletes, but that’s absolutely not the case. Adequate protein intake is not only critical for health and well-being, but “eating protein before a run helps reduce muscle breakdown and can help improve recovery,” Brown says. 

[Read More: The Benefits of Protein for Health and Performance]

Like carbohydrates, the amount of protein to intake before a run depends on how much time you have before you head out. “The more time you have before a run, the more total food volume, protein, fat, and fiber you will be able to tolerate because there is more time for digestion,” Brown explains. 

She outlines the ideal protein intake before a run:

Eating 2 to 3 hours before you run: 20 to 25 grams

Eating 1 hour before you run: 10 to 15 grams

Eating 15 to 30 minutes before you run: 0-5 grams 

Electrolyte Needs

Another important element of running fuel is electrolytes. While electrolytes don’t provide calories and therefore may not be considered “fuel,” these minerals are critical for running performance—and your health. 

[Read More: Learn How to Make a Homemade Electrolyte Drink from a Certified Nutrition Coach]

“Electrolyte replacement needs are individual,” Brown says, noting that the best way to find out how much fluid and how many electrolytes you need is to take a sweat test. Sodium loss tests estimate how many milligrams of sodium you lose per liter of sweat. You can calculate fluid losses by weighing yourself before and after training and subtracting the weight of fluids you consumed during training.

Hydration needs are also affected by various factors, such as pace and weather. According to Brown:

Slower runners are at a higher risk of drinking too much water and not enough electrolytes, which could lead to hyponatremia.

If you are a heavy sweater, salty sweater, and/or train in hot or humid environments, it is a good idea to include electrolytes around training (before, during and/or after) and with regular food intake.

Higher-intensity runs may require more electrolytes than lower-intensity or shorter runs due to increased sweat/electrolyte loss.

What Are Energy Gels for Runners?

Energy gels, also called running gels, are small packets of a sugary substance. Typically, the substance consists of glucose and fructose, two fast-absorbing sugars that your body can quickly utilize for energy during training runs or on race day. Energy gels usually contain sodium, too, and sometimes contain other electrolytes, caffeine, vitamins, minerals, and/or amino acids. 

These gels intend to replenish circulating carbohydrates—sugar available in your bloodstream—before your body taps into and exhausts your stored carbohydrates (glycogen), which are very finite. The idea is to keep your body running on inputs (gels/sugar) rather than stores (glycogen) while enduring long training sessions or races.

Before you run out and buy a stash of gels, know that you might not need them. For one, there are many other ways to intake intra-workout calories, some ideas being blended or chopped fruit, candy, and sugary sports beverages. 

More importantly, though, it’s crucial to understand when energy gels (or intra-workout fuel at all) are needed, and when they’re not. The general rule of thumb is that athletes should take intra-workout fuel for sessions lasting longer than 60 to 75 minutes, explains Brown. 

There are certainly exceptions to that rule, though. 

For example, Brown says that athletes should intake fuel during high-intensity runs lasting less than 75 minutes if the athlete is training for an event.

Triathletes, too, have different fueling needs. For instance, if a triathlete is performing a bike-run brick workout, the athlete will benefit from taking an energy gel upon starting the run, even if the run is only 30 minutes in length. 

Weather conditions can make a difference, as well. Runners may need more intra-workout fuel while training in hot, humid conditions, especially if they are not acclimated to those conditions. 

Best Fuel Before Your Run

The best fuel before your run depends largely on how much time you give yourself to digest. Chavez explains that if you eat two to three hours before you run, you can eat an entire meal. 

“Aim for a balanced meal high in carbohydrates, moderate in protein, and low in fat,” he says. “About 60 to 70 percent of the calories should come from high- to moderate-glycemic carbohydrates, 10 to 20 percent from high-quality protein, and 20 to 30 percent from unsaturated fats.” 

If eating one hour before your run, Chavez says to “aim for easily digestible carbohydrates that are low in fiber to provide quick energy without causing gastrointestinal discomfort during the run.” Also, keep protein and fat intake low to avoid slowing down digestion, he says. 

Lastly, if you’re eating less than one hour before your run, Chavez says it’s essential to prioritize high glycemic, low-fiber carbohydrates with minimal protein and fat to aid in quick digestion.

Fueling for Different Types of Runs 

The type of run you plan to do will heavily influence what stands as proper or adequate fueling. For longer or higher-intensity runs, you will need more fuel; for shorter or lower-intensity runs, you’ll need less. 

You may wonder if you need a specific pre-run meal or snack if your day calls for a short, low-intensity session. Brown explains that specific fueling can be helpful for runs lasting less than an hour if: 

You want a high-quality run

You are participating in high-intensity interval training

You’re training at threshold paces 

You’re training for specific adaptations (e.g., increasing speed)

Your run is taking place early in the morning, before breakfast

Best Fuel During Your Run

Chavez says that “intra-run fuel such as gels, sports drinks, or other carbohydrate sources should be considered when the activity duration exceeds 60 to 90 minutes.”

“After an hour, the body’s glycogen stores become depleted, and blood glucose levels begin to drop,” he says, “leading to fatigue and a decline in performance.”

Credit: verca / Shutterstock

Mid-run fuel may also be necessary or beneficial for shorter sessions if you’re training at particularly high intensities or looking for specific adaptations. 

The important thing is to ensure you take in enough carbohydrates to keep your performance up for the duration of your session. According to Brown, runners should aim for 30 to 90 grams of carbohydrates per hour, depending on the intensity of the session, training goals, and body weight. Smaller athletes generally need fewer intra-workout carbs than larger athletes. Lower-intensity training requires fewer carbs than higher-intensity training. 

Best Fuel After Your Run

Fueling up doesn’t stop when you’re done running. In fact, your post-run meal can make a significant difference in your performance the next day—for better or for worse. 

“To maximize recovery and optimize performance the following day, runners should consume a post-run meal with protein, carbohydrates, fluids, and electrolytes,” Chavez says. “A general guideline is to ingest a mixed meal with a 3-to-1 carb-to-protein ratio. For instance, a meal containing 30 grams of protein should contain at least 90 grams of carbs.” 

Chavez recommends choosing high-quality lean protein sources, such as chicken, turkey, fish, egg whites, and lean cuts of beef. For carbohydrates, choose some with high-to-moderate glycemic index carbohydrates, such as white rice, pasta, or sports drinks containing carbohydrates, Chavez suggests. 

[Read More: What to Eat After a Workout — How to Find the Right Refueling Sources]

Additionally, Chavez says it’s essential to replace fluids and electrolytes after a run. “For every pound of weight lost, ingest 16 ounces of fluids with carbohydrates and electrolytes.” 

Electrolyte drinks like Nuun, Liquid I.V., LMNT, and DripDrop ORS can help you rehydrate. 

Carbohydrate Timing

In endurance training, post-workout carbohydrate timing may impact your recovery and performance. (3)

“Carbohydrate timing is essential, particularly following a bout of exercise, to maximize glycogen resynthesis and replenish energy stores effectively,” Chavez explains. “Glycogen, the body’s stored form of carbohydrate, maintains performance during prolonged or intense runs,” so it’s critical to replenish as much as possible following a training session. 

Failing to replenish glycogen stores means you may begin your next session without maximum stored energy, which in turn leads to quicker fatigue and impaired performance. (3) 

Benefits of Running Fuel

“Fasted cardio” may be past its heyday, but it’s very much still a popular concept. Running in a fasted state is perhaps best known for its purported effect on fat oxidation (fat burning), and it also has applications in endurance training for helping athletes become “fat adapted” (i.e., shifting the body away from reliance on carbohydrate and “teaching” it to use fats as fuel instead.” (4)(5)

And, understandably, some runners may prefer to run on an empty stomach if digestive problems persist while running after eating. 

But there are a host of convincing reasons to fuel up before, after, and even during training.

It Delays Fatigue

“Running in a fueled state helps you sustain higher intensities for longer and increase energy during runs,” Brown says. Additionally, fueled running “improves recovery and post-run muscle soreness, reduces muscle breakdown improving endurance and recovery, and helps you stay mentally focused.”

[Read More: Do You Really Need High Glycemic Carbs Around Your Workout?]

“Fueled running is especially beneficial for intense or prolonged workouts, such as high-intensity sprints or long-distance running,” Chavez says. “Having adequate liver and muscle glycogen stores (the body’s storage form of carbohydrates) before a run can help delay fatigue and maintain a higher intensity for longer.” (6) 

It Improves Performance

Additionally, “Consuming carbohydrates beforehand can enhance endurance and improve performance, particularly during runs that are longer than an hour,” he says. 

Indeed, studies have shown that running in a fed state consistently improves prolonged performance and that running in a fasted state can impair prolonged endurance. (7)(8)

It Helps With Recovery

By eating before your run, you’re helping yourself out post-run. There are two reasons for this: 

When you run in a fed state, you are less likely to tap into and exhaust your glycogen stores. So, it’s not as difficult to replenish glycogen afterward and you’re more likely to start your next session with maximal stored carbohydrate. 

When you eat before you run, particularly if you eat a meal containing protein, your body is less likely to sustain substantial muscle protein breakdown. In other words, eating before you run can help preserve muscle tissue and minimize post-run muscle soreness. Additionally, some research has found that consuming both protein and carbohydrates (as opposed to just carbohydrates) after training can lead to better recovery in endurance athletes. But importantly, eating sufficient protein daily is the most critical factor. (9)(10)(11)

Frequently Asked Questions

References

Podlogar T, Wallis GA. New Horizons in Carbohydrate Research and Application for Endurance Athletes. Sports Med. 2022;52(Suppl 1):5-23

Veniamakis E, Kaplanis G, Voulgaris P, Nikolaidis PT. Effects of Sodium Intake on Health and Performance in Endurance and Ultra-Endurance Sports. Int J Environ Res Public Health. 2022;19(6):3651

Bonilla DA, Pérez-Idárraga A, Odriozola-Martínez A, Kreider RB. The 4R’s Framework of Nutritional Strategies for Post-Exercise Recovery: A Review with Emphasis on New Generation of Carbohydrates. Int J Environ Res Public Health. 2020;18(1):103

Aird TP, Davies RW, Carson BP. Effects of fasted vs fed-state exercise on performance and post-exercise metabolism: A systematic review and meta-analysis. Scand J Med Sci Sports. 2018;28(5):1476-1493

Yeo WK, Carey AL, Burke L, Spriet LL, Hawley JA. Fat adaptation in well-trained athletes: effects on cell metabolism. Appl Physiol Nutr Metab. 2011;36(1):12-22

Aandahl MH, Noordhof DA, Tjønna AE, Sandbakk Ø. Effect of Carbohydrate Content in a Pre-event Meal on Endurance Performance-Determining Factors: A Randomized Controlled Crossover-Trial. Front Sports Act Living. 2021;3:664270

Aird TP, Davies RW, Carson BP. Effects of fasted vs fed-state exercise on performance and post-exercise metabolism: A systematic review and meta-analysis. Scand J Med Sci Sports. 2018;28(5):1476-1493

Aziz AR, Wahid MF, Png W, Jesuvadian CV. Effects of Ramadan fasting on 60 min of endurance running performance in moderately trained men. Br J Sports Med. 2010;44(7):516-521.

Williamson E, Fung HJW, Adams C, West DWD, Moore DR. Protein Requirements Are Increased in Endurance-Trained Athletes but Similar between Females and Males during Postexercise Recovery. Med Sci Sports Exerc. 2023;55(10):1866-1875.

Vitale K, Getzin A. Nutrition and Supplement Update for the Endurance Athlete: Review and Recommendations. Nutrients. 2019;11(6):1289.

Jäger R, Kerksick CM, Campbell BI, et al. International Society of Sports Nutrition Position Stand: protein and exercise. J Int Soc Sports Nutr. 2017;14:20

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