As a runner, checking off kilometres obviously has a prominent spot on your schedule. To get through all those kilometres, you have to fuel up so you have the energy to perform. But whether you run in the morning or after work, you may be wondering when to get your fill of kilojoules and nutrients. In other words, should you eat before or after a workout?

The problem with skipping food before a workout is that it can hinder your performance. By not taking in enough calories to fuel your run, you may suffer from “low energy availability” and related complications such as higher stress hormones and decreased metabolic rate, says dietitian Namrita Brooke, adjunct professor in the Department of Movement Sciences and Health at University of West Florida and Runner’s World sports dietitian and nutrition advisor.

You may also pay a price for not eating after a run, as fueling up can help boost recovery. According to a 2021 paper, the “4Rs” of post-exercise recovery are rehydration, refuelling, repair and rest. To refuel, you need carbs, the primary source of energy used during exercise, and to repair your muscles, you need high-quality protein, the muscle-building macronutrient.

While it can feel like a chore to prioritise nutrition along with all of your training, here’s how to determine if you should eat before or after a workout to support your performance, based on the workout you have on deck and other factors.

Questions to Ask to Determine If You Should Eat Before or After a Workout

➥Are you hungry or do you typically get hungry midrun?
Your own body gives the best advice, so if you feel hungry before you start a workout, don’t hesitate to eat. Even a small snack of about 400 to 500 kilojoules can boost your energy, especially if you plan to run for 30 minutes or less and maintain a zone 2 effort, Brooke says. On the other hand, feeling hungry may force you to cut your run short or keep you from hitting your goal paces.

Rayven Nairn, senior registered dietitian for Student Health and Wellbeing at Johns Hopkins University, tells Runner’s World that simple carbs like a rice cake or a granola bar work as pre-run snacks. “They are amazing — literally a shot of sugar — and will prevent you from hitting the wall,” Nairn says.

If you have the time, it’s smart to eat a bigger meal about 90 minutes before you hit the road. This will give you time to digest more complex carbs, as well as fat and protein in your meal, says Nairn. Smoothies serve as a good option before a workout, as they’re easy to digest and can give you the essential carbs needed to run well, Nairn adds.

➥How long are you exercising?
If your run is under an hour and you aren’t hungry, you can likely get through the workout without food beforehand and simply refuel afterwards with a complete meal that includes carbohydrates, protein, some fat, and hydration, says Brooke. She recommends a bowl of oatmeal with some nuts, seeds, and fruit preserves after a morning run, and often pairs it with a protein drink to get in extra fluids.

For runs longer than an hour, aim for a full meal about 90 minutes before you head out. Then, fuel with about 30 grams of carbs, such as an energy gel, every 30 to 45 minutes during your run, says Nairn.

One more thing about long runs: You want to refuel afterwards. Smoothies are a solid option for after your run, too, Nairn says. She makes hers with 80-180 ml of yoghurt, ½ cup to 1 cup of fruit, and one scoop of protein powder. You’ll get carbs to replace the energy you used during your workout and protein to rebuild muscles. Plus, the fruit offers hydration, along with antioxidants.

➥How hard or how fast are you running?
If you are running hills or intervals for more than 20 minutes, you should eat at least a small carbohydrate-based meal or snack before the workout, both experts say. A couple pieces of toast with cinnamon and sugar or butter and honey are quick and easy to digest pre-workout.

For runs longer than 75 minutes, consider taking in carbohydrates during the workout, too, says Brooke, especially if it will include intensity, such as sprints or tempo efforts. Gummies, gels, and sports drinks are all convenient choices.

➥Is it early in the morning?
If you’re going out fast or long in the morning, says Nairn, one serving of carbs (for example, one slice of toast) paired with one serving of protein, such as two tablespoons of peanut butter, is most beneficial for energy availability. Another option is a hard-boiled egg and a small apple.

This advice might seem contradictory for those who aim to do “fasted cardio,” or running after not eating for six to eight hours (often in the morning, after you wake up), which many runners turn to for weight loss or because they believe it will help them burn more fat — but this isn’t necessarily true.

According to Brooke, there is evidence that fasted training diminishes performance. And, as shown in a 2018 review article published in the Scandinavian Journal of Medicine and Science in Sports, eating before an aerobic workout prolongs performance and may have benefits to your metabolism.

There are also possible risks to doing fasted workouts regularly. Some of these, according to Brooke, include higher levels of fatigue, increased perceived effort, disrupted sleep, low energy availability that can lead to hormonal and immune dysfunction, and lower performance. So if you’re looking to pick up your pace, running fasted probably isn’t the best option for you.

The Bottom Line on Eating Before or After a Workout

When you head out for a run, your body turns to stored carbs (a.k.a. glycogen) as its first source of energy, says Nairn, which is why it’s so important to get your fill of carbs before a workout. Without that gas in the tank, it’s more difficult to maintain stamina and intensity.

Something is better than nothing when it comes to fueling before a run, too, so even if you don’t have time for a full meal before morning exercise, a quick snack (like a slice of bread and peanut butter) will set you up for a better workout.

Making sure you eat after a run can help jumpstart the recovery process, which gets you ready for the next workout. While carbs are also important after a workout, protein plays a crucial role in that post-run meal or snack. (That is especially true after strength workouts.)

Nairn and Brooke both recommend having combined carbs and protein after a run, aiming to get in a combo about 45 minutes to an hour after you’re done. They suggest a peanut butter sandwich with an orange or two hard-boiled eggs with a grapefruit and buttered toast.

Hydration is also key both before and after a workout, with something like a sports drink serving well post-run for added electrolytes, Nairn says.

Finally, the most significant research regarding nutrition and running isn’t necessarily about meal timing, but about the consistency of healthy eating. So look at your diet as a whole to make sure you’re getting in enough calories to fuel your workouts, along with plenty of carbs, protein, healthy fats, and micronutrients to keep you running strong.

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