Should You Eat Before Working Out?

We need healthy food to fuel our bodies in all of our daily activities—and working out is no exception. 

The short answer is yes, you should eat before exercising—but how much, what, and when you eat can vary widely depending on the workout you’re going to be doing.

You don’t want to show up to the gym or a race feeling depleted and starving, but you also don’t want to be too full (no Michael Scott carbo-loading with fettuccine Alfredo, please!). 

Let’s explore the world of sports nutrition and learn about what to eat before a workout, when to eat it, and how the different macronutrients affect exercise abilities. 

Pre-Workout Nutrition Basics

Eating small or moderate amounts of carbohydrates and protein before a workout helps you to perform better and recover faster. Healthy fats can also help, but you don’t want to eat too much of them before exercising. 

However, eating too much or too close to your workout of any food can also impede your performance, primarily because it can cause you to feel sluggish or have an upset stomach. 

So what’s the magic formula? Let’s take a look at the three macronutrients and how proper nutrition can impact exercise and athletic performance. 

Carbohydrates and Exercise

Carbohydrates are an essential component of a pre-workout snack or meal, as they are the direct fuel our cells use to power our muscles to exercise. They can also help you to work out harder and for longer. 

When we eat carbs—like fruit, veggies, milk, brown rice, whole-grain bread, etc.—our body turns them into glucose, the primary form of energy our cells prefer to use. 

If we have excess glucose hanging around, it gets stored as glycogen primarily in the liver and muscles, acting as an energy reserve for when it’s needed.¹

Liver glycogen is the only type that can turn back into glucose in the bloodstream, while muscle glycogen only fuels muscle cells, which is why your body prefers to use muscle glycogen stores first when exercising.¹ 

However, your glycogen stores are limited. When they run low—typically at about 80-120 minutes of steady-state exercise—your athletic performance and physical abilities will also decline.¹ 

Understandably, the more intense workouts you perform, the quicker your glycogen stores will deplete. Activities like high-intensity interval training or sprinting tend to drain glycogen the fastest. Longer, endurance-style workouts—like a marathon—also deplete glycogen, but at a slower rate.¹ 

Your body can use circulating blood sugar (glucose) for energy during exercise (like the carbs you just ate), but it prefers to use muscle glycogen stores and will use those first. 

That said, ingested glucose is easily metabolized during exercise, meaning if you have something sugary or carb-rich just before or during a workout, it will get used for fuel instead of getting stored as fat.²

According to researchers published in Nutrients, “[T]he depletion of glycogen levels is a limiting factor of performance during sessions in which high exercise intensities are required; therefore, ensuring a high CHO [carbohydrate] availability before and during exercise is of major importance.³

How many carbohydrates you eat before a workout depends on the intensity of the upcoming workout and how much time you have. 

Researchers recommend that athletes consume 1-4 grams of carbohydrates per kilogram of body weight before exercise, with more for high-intensity exercise and more hours before the workout.³

However, most of us are not elite athletes, so 1g/kg would probably be plenty for a regular ol’ gym session. For example, this would mean that a 150-pound person would consume 68g of carbs before a workout (if you have at least 1 hour beforehand to digest it). If you have more time (let’s say a few hours) and anticipate more intensity, you could consider bumping it up to 2g/kg. 

For reference, there are about 15g of carbs in 1 slice of whole-wheat bread, ½ of a large banana, or 1 tablespoon of honey.

The bottom line: Yes, you should eat carbs before a workout—especially for endurance athletes, high-intensity interval training, or longer workouts—to supplement your glycogen stores. This will allow you to work out for longer or with higher intensity before tiring.

Protein and Exercise

Eating protein before a workout can also improve athletic performance and recovery.

According to one study, “There is robust evidence which shows that consuming protein pre- and/or post-workout induces a significant rise in muscle protein synthesis.”⁴

Muscle protein synthesis is essential for growing muscles, which is what most people who exercise aim to do. Therefore, you need to eat protein and essential amino acids to build muscle.

You may wonder if you have to consume protein both before and after a workout. Contrary to popular belief, you don’t have to eat protein directly in the 1-hour window after a workout—total protein intake throughout the day in a healthy diet pattern matters more.⁴

You may also feel like you can work out more intensely or for longer if you have some protein before, but you don’t want to eat too much. 

Therefore, a moderate amount of protein would be a good amount to support your workout. This could be anywhere from 10g to 30g of protein, with amounts increasing if you have more time (two hours or more) beforehand. 

If your workout involves lifting weights or strength training, you may want to go towards the upper end of the range (provided you give yourself enough time to digest the food before the workout) to support muscle protein synthesis.

Fat and Exercise

Fat is less important to eat before a workout than carbs and protein, but it still has its use. 

Fat can be the source of fuel when you run out of glycogen—like during really long runs—so it can be helpful to have some in your pre-workout meals. 

You definitely don’t want to overdo fat before a workout, as it digests slowly and could cause some significant digestive issues and stomach discomfort. 

Try to keep preworkout fat to about 10 grams, about 15 almonds, ¼ of an avocado, or just under 1 tablespoon of olive oil.

When to Eat Before a Workout

The ideal scenario would be eating a complete and balanced meal of carbohydrates, protein, and healthy fats 2 to 3 hours before your sweat session. This would give your body enough time to digest the food and build up glycogen stores without causing digestive problems. 

If you have about two hours, pre-workout meals include protein smoothies made with low-fat milk (or non-dairy milk), protein powder, almond butter, and fruit, a PB & J sandwich, a turkey sandwich, or scrambled eggs with cheese and a piece of whole-wheat toast.

However, you don’t always have that time—especially if you’re heading to an early morning workout class. 

If you have an hour before a workout, choose a light meal with easy-to-digest carbs and a little bit of protein, like a protein bar or Greek yogurt with berries. If you aren’t sensitive to dairy, some low-fat or even chocolate milk can be a good option to include. 

Combining these macronutrients is ideal for both a solid workout and your recovery after. The International Society of Sports Nutrition states: “Consuming carbohydrates solely or in combination with protein during resistance exercise increases muscle glycogen stores, ameliorates muscle damage, and facilitates greater acute and chronic training adaptations.”⁵ 

Less than an hour before, you should opt for a light meal (more like a mini snack) that is very easy to digest and works for your digestive system, like a banana or simple smoothie.

Lastly, don’t forget about staying hydrated—especially if you’re exercising outside in the warmer months. Consume enough water before and during your workout to maintain proper fluid balance. 

The American Council on Exercise recommends drinking 17 to 20 ounces of water 2 to 3 hours before your workout and 7 to 10 ounces of fluid every 10 to 20 minutes during exercise. 

Eating Before a Workout FAQs