You probably know it’s not the best idea to work out completely starving—if it’s been hours since your last meal, you likely won’t have the energy to make it through your sweat session—but exercising with a full stomach isn’t ideal, either. So, if you’re trying to plan your day, is it better to eat something before working out, or wait until after you’ve finished to fuel up?

“A simple answer to whether someone should eat before or after a workout is ‘Yes, both,’” says Frank B. Wyatt, a professor in the department of athletic training and exercise physiology at Midwestern State University. “But life is not simple.” 

In other words, he says, there are situations in which a person might need to eat something shortly before exercise, as well as times when it’s likely better to wait. But it all depends on your individual circumstances, such as when you last ate, the time of day you’re planning on working out, and how intense your workout will be.

Below, what to know when considering whether you should eat before or after a workout (or both), plus whether there’s ever a reason to snack during exercise.

Should You Eat Before or After a Workout? 

The short answer to this, like so many nutrition questions, is that it really depends on the situation. But according to Wyatt, it’s smart to think about how you’re going to fuel yourself before a workout, as well as what you’ll eat to support your recovery after. Ideally, he says, you’d nosh on a meal that delivers solid energy about three hours before exercise, then have a nourishing snack within two hours of completing your workout.

“Generally, there should be a three-hour post-absorptive time between eating and working out,” he explains. “And the timing for a post-workout feeding is even more crucial: There’s a window of feeding to replenish and restore muscle glycogen levels post-exercise, [and] that window is around two hours.”

Of course, it’s not always possible to structure your day so you have a perfect three-hour window between meals and exercise. For example, what if you have a 1 PM lunch appointment and you’re hoping to squeeze in a short indoor cycling session before your next meeting at 4 PM? Or what if the only time you have to work out is first thing in the morning? 

When considering whether or not to eat something before a workout or wait until you’ve finished, ask yourself these questions:

When to Eat Before a Workout

Generally, it’s smart to eat before a workout if it’s been four hours or more since your last meal, if you’re planning to do a longer or more vigorous workout, or if you feel hungry.

That said, it’s also important to consider what and when you’ll eat. While you don’t want to be lifting weights or pedaling through a tough indoor cycling class with a rumbling stomach, eating too close to a workout—or filling up on difficult-to-digest foods—can have uncomfortable downsides, experts say. 

For one, eating before a workout can lead to an upset stomach, notes Lena Bakovic, RDN, a registered dietitian based in Palm Beach Gardens, Florida. That’s particularly true if you nosh on high-fiber or high-fat foods, which take longer to digest. “Some people who eat too close to their workout time can experience gastrointestinal distress, with issues such as nausea, vomiting, or even diarrhea,” she says.

Plus, a big meal just before exercising might make it harder for you to meet your workout goals. “Generally speaking, you don’t want the digestive process going on when you exercise,” Wyatt says. Digestion directs blood flow to the gut, he explains, and you need that blood flow to be heading toward your muscle tissues during a sweat session.

That’s why it’s best to wait around three hours after a large meal to exercise: This gives your body enough time to absorb the nutrients you ate to fuel your workout without detracting from it (or leaving you feeling overly full or, on the other end of the spectrum, hungry and lightheaded).

If you do decide to eat a little closer to your workout—perhaps because you feel hungry or it’s been longer than four hours since your last meal—Bakovic recommends a small snack that includes a complex carbohydrate and a protein (for example, a banana or apple with peanut butter). “This helps with optimization of performance,” she says, since carbohydrates help keep blood glucose levels high and prevent muscle fatigue.

When to Eat After a Workout

If you’re not hungry, you don’t have to eat something right after completing a less fatiguing workout, like an easy walk or low-intensity yoga flow, according to some experts. In those cases, a balanced meal at your next usual time will usually be enough. But if you just knocked out a longer or higher-intensity workout, such as a tough lifting session or a strenuous endurance ride, it’s especially important to refuel. Ditto if you’re hoping to build muscle or if you simply feel hungry.

That’s because when you exercise, your muscles use up glycogen—a form of glucose and your body’s main source of energy—to get the fuel they need to complete your workout. That’s why experts generally recommend eating within one to two hours after exercising to replenish these nutrient and glycogen losses. “This timing also helps with muscle repair,” Wyatt says. 

After a workout, your best bet is to consume foods that contain both carbohydrates and protein, experts say. Wyatt recommends chocolate milk, since “it has both carbohydrates and protein and generally goes down easy.”

Should You Eat During a Workout, Too?

Most of us don’t usually need to eat while working out—an energy-boosting meal a few hours before plus a replenishing snack after should be enough. But if you’re working out for a particularly long time or at greater-than-average intensity (think: running a marathon) you might need a boost mid-exercise, too. 

“If the workout is exceeding 60 minutes and the intensity is moderate to high, some level of feeding should take place,” Wyatt says. The main reason to have a small snack during a workout, he explains, is to keep blood glucose levels up. Otherwise, you might experience something called muscle glycogen depletion, which causes your muscles to fatigue and prevents you from continuing to push yourself at the same intensity. This is sometimes referred to as “hitting the wall” among runners or “bonking” among cyclists, Wyatt adds.

As for what to eat during endurance-type workouts? Bakovic recommends something high in carbohydrates, such as an energy gel, sports drink, or a banana.

The Takeaway

Whether you should eat before or after a workout largely depends on your planned exercise length and intensity, when you last ate, how much time you have before you exercise, what you’re planning to eat, and how hungry you are. But in general, experts recommend eating a balanced, energizing meal about three hours before working out and eating within two hours after exercise to support your recovery.

That said, you know your digestive system best: “I think it’s important to know your own body and recognize how it responds to food before a workout,” Bakovic says. Some people might be able to tolerate a snack a little closer to their workout, for example. And if you’re someone who’s engaging in intense, endurance-type activities such as running a marathon, you’ll likely want to have a small snack like a banana while exercising, too.