What to Eat Before a Run, According to Dietitians Who Specialize In It

Figuring out what to eat before a run can be tricky. Sure, you’ll typically run better if you can take in some calories to fuel your miles. But if you eat the “wrong” thing before lacing up, your stomach could revolt. 

“You’re up against how quickly and how efficiently you can digest and absorb the food that you’ve consumed,” says registered dietitian Stephanie Hnatiuk, RD, who specializes in working with runners. Typically, after a meal, our blood flow is largely focused on our gut so that our bodies can effectively take in all those nutrients we just ate. But once we start running, our bodies prioritize sending blood to the muscles in our legs instead. So if you’ve still got a lot of undigested food sitting around in your stomach, you could end up with diarrhea and other unpleasant symptoms of runner’s stomach.

Of course, every runner is different, and while some might be able to scarf down a burrito before knocking out a sprint workout, others can’t handle much more than a few sips from a sports drink. Still, there are some general guidelines that sports dietitians commonly recommend when it comes to what and when to eat before a run. If you’re struggling to figure out exactly what you should munch on ahead of your miles, here’s what you need to know.

Should You Always Eat Before a Run?

Generally speaking, it’s a good idea to have a little bite before lacing up. “It’s better to eat than not eat before a run, even if you’re not hungry,” says registered dietitian Serena Marie, RD, who specializes in working with female runners. 

That said, it’s not always an absolute must-do when you’re really not in the mood for a snack. If you’re just heading out for an easy recovery run that’s going to be less than 30 or 45 minutes long, you can probably get away with relying on your body’s glycogen stores for fuel without having an extra nibble. 

But if you’re planning on anything more intense—think hill runs, tempo runs, interval training, or long runs—you’ll want to give your muscles some carbohydrates first. “The science has been decades long, very rigorous, very clear on this point that performance is improved by having fuel available to be able to perform at those higher intensities,” Hnatiuk says. 

Think of it this way: If you’re going to put a ton of energy and effort into the workout itself, why wouldn’t you also do what you need to make sure your body is fueled enough to pull it off as powerfully as possible? 

If you’re preparing for a race, there’s also something to be said for training your gut—and giving yourself time to experiment with different foods so you find what will work best for you on race day. “The practice of having food in your stomach consistently before you run is really valuable from the perspective of teaching your body to be able to simultaneously break down food while you’re exercising,” Hnatiuk says. Even if you currently get a little queasy when you snack pre-run, starting small with just a few crackers or a little juice can help improve your tolerance over time.

What to Eat Before a Run

The ideal pre-run bite to eat doesn’t look like the kind of food that dietitians recommend during the rest of your day. “I always joke around that the pre-workout snack is kind of a weirdo,” Marie says. “Usually, I really want clients to have lots of fiber and protein and greens. I’m really encouraging color. But with pre-run snacks, we’re really thinking about what is going to digest really quickly.”

That includes the simple carbs that you’d normally give a toddler. These are carbs that your body breaks down fast, such as graham crackers, white bread, cereal, toaster pastries, and juice. Marie suggests having some of those along with a sports drink that has some sugar and electrolytes in it, aiming to take in around 0.5–2 grams of carbohydrates per pound of body weight before a hard run. (So if you weigh 150 pounds, having about 75–300 grams of carbs before pounding the pavement would put you in the sweet spot.) 

If this sounds different from what personal trainers have told you about pre-workout fuel in the past, there’s a reason: “The way we fuel for a run is definitely different than how we would want to fuel for a lifting workout,” Marie says. When you’re strength training, protein is really the star of the show to help you build that muscle mass (just always be sure to give yourself enough time to digest it first, regardless of your workout). But for endurance sports like running, you need carbohydrates that provide the glycogen that fuels your muscles for long miles. And with running in particular, you want something that will digest easily, even when you’re jostling your organs up and down with each stride. 

What to Eat Before a Long Run

When you’re heading out for a long run—meaning, anything that’s going to last longer than an hour—you’ll want to take in more calories and have some fuel that’s going to sustain you for a while. That means adding in a little protein and fat to your pre-run carbs to keep your blood sugar balanced and supply a more steady stream of energy over the course of your workout. For instance, Marie suggests having a bagel with peanut butter and banana slices, or a hard-boiled egg with some toast and a sports drink.

Just don’t try to scarf down all the calories you’re about to burn running beforehand. “We’re just trying to get something in the tank so that we can not have low blood sugar or completely run out of glycogen during the run,” Hnatiuk says.  

Also: If your stomach can’t handle a big meal shortly before running (more on that below), it’s OK to stick to smaller portions. Just top off your energy stores with an applesauce squeeze packet, a gel, or a handful of gummy bears a few minutes before hopping on the treadmill or heading out the door, Marie suggests.  

What to Eat Before a Shorter Run

For any run that’s under an hour, you can skip the extra protein and fat, and just focus on those simple carbs like crackers or juice to give your body something to burn quickly without risking gastrointestinal (GI) issues. “If you’re doing a shorter effort, by the time you start getting hungry, hopefully your workout is ending and then you can just eat your next meal,” Marie says.   

How Long Before Running to Eat

Pre-run fuel typically focuses on the food you eat in the hour and a half before exercising. (For any meals that happen earlier than that, you don’t have to worry so much about those easy-digesting carbs, Hnatiuk says—eating a normal, balanced meal will do just fine.) Within that 90-minute pre-run window, the exact amount of time you need to leave between eating and running varies from athlete to athlete. And it can change based on what you’re planning to eat.

“The further out you are from the run, the bigger meal you could have,” Hnatiuk says. “And the more mixed—you could have a little bit more fiber, a little bit more protein, maybe a little bit more fat.” 

If you’ve got 60–90 minutes to spare before running, your stomach is more likely to be able to take in that well-rounded meal without having any negative after-effects. On the other hand, if you only have 15 minutes or less, Hnatiuk suggests focusing just on carbs that are designed to be broken down quickly, like those in sports drinks, gels, or chews. 

Foods to Consider Avoiding Before a Run 

Almost as important as what you eat before a run is what you don’t eat. Although some runners have guts of steel, most of us need to tread carefully when it comes to protein and fat. Although a little can be helpful for providing sustained energy (as long as you give yourself enough time to digest them), eating too much protein and fat too close to the start of your run can backfire. “For instance, having a little bit of avocado would be fine. But if you ate a whole avocado before your run, that could potentially cause a lot of GI distress,” Marie says.

The same is true of fiber. Although fiber is typically a healthy part of most meals, many runners will avoid eating too many high-fiber foods starting the night before a long run or race to make sure it won’t wreak havoc in their systems once the run begins. 

One other thing you might want to avoid is sugar alcohols. These are ingredients found in many “diet foods” as a way to cut calories. (You can spot them easily on ingredient lists because they end in -ol: xylitol, sorbitol, maltitol, erythritol.) “Those can act as laxatives,” Marie says. Not an ideal scenario unless you want to be sprinting between porta-potties.

Surprisingly, sports drinks that are too concentrated can also lead to GI issues. Experts generally recommend reaching for a bottle with a carb concentration of no more than 8 percent. Marie says you want “just the right amount of sugar to help your body absorb the electrolytes—the sodium, the potassium, the magnesium—but not too much sugar that it causes a GI issue.” Also, chugging too much of any liquid before running won’t make you feel great if you drink so much that your intestines are waterlogged. 

The Takeaway

The foods that sports dietitians recommend eating before a run—simple, fast-digesting carbs—may seem counterintuitive since they’re the opposite of what’s typically recommended for a healthy diet. But they’re your best bet when it comes to what to eat before a run. “We have to get away from this idea of there being ‘good’ foods and ‘bad’ foods, and instead think about just choosing the right food at the right time,” Hnatiuk says. “I wouldn’t recommend a glass of fruit juice for supper. But we have to think about what we need in the moment for optimal performance.”

Everyone’s stomach is a little different, and it might take some trial and error to discover what sits well in yours while running. But even if you struggle with eating before a run, it’s worth it to keep trying. 

“If you feel like you’re a person who gets sick every time you eat before a run, usually, that just means you have to keep testing things out and figuring out what works for you,” Marie says. Start small with just a few bites (or sips) of carbs. If you can train your stomach to handle it, you’ll feel a heck of a lot better—and just might end up running faster—if you’re fueled on your runs.