But do you grab a snack to get more out of your workout? Or skip the food to avoid stomach cramps and potentially "undo" everything you're about to accomplish?
And if you do choose to fuel, should that be with a protein shake, an energy bar, a handful of nuts or a piece of fruit?
Pre-workout snacks shouldn't make you feel stuffed but it is important to eat up, says Cynthia Sass, a registered dietician. "Exercising on an empty stomach can lead to the breakdown of muscle tissue," cautions Sass.
Without food to fuel your workout, muscle tissue is instead converted into glucose to provide the energy you need, which isn't ideal -- whether you're trying to build muscle or lose weight. This breakdown can negatively impact your metabolism and might even lead to injury.
Food for thought
In order fuel up properly pre-workout, it's important to understand how the body uses energy. Chris Mohr, a registered dietician who has a PhD in exercise physiology, says the first source of energy, lasting just a few seconds, comes from the breakdown of adenosine triphosphate (ATP), which is naturally found in the body.
Next, the body uses glucose (sugar) for immediate but longer lasting energy. Finally, during endurance training, the body starts to break down stored carbohydrates, called glycogen, to provide sustained energy.
"The type of workout itself, and the duration, will affect the different processes taking place in your body," says Mohr. So the duration and intensity of your workout will determine your energy needs.
Knowing how to best fuel your body can help you get the most out of every sweat session and get you one step closer to achieving your goals. Here are the fundamentals to fuel for success.
1. Time it right
As a general rule of thumb, when it comes to pre-workout eating, "you can time it any way you like, but the closer you get to a workout, the more simple the meal should be," says Sass.
If you eat two to three hours before, you'll have time for your food to digest and be absorb from your GI tract into your blood. Therefore, you can eat a more complex meal containing protein, fat and fiber, which take longer to break down.
"Within an hour of a workout, however, you should eat something that will be digested and absorbed more quickly," says Sass (like a small bowl of cereal or a piece of fruit).
Not only is undigested food useless as fuel, it can feel heavy in your stomach, leading to cramps and sluggishness, she says.
2. Assess intensity
Now don't go thinking simply lacing up your sneakers justifies a big, hearty snack! The amount of effort you put into your workout will dictate what you should be consuming prior to exercising.
"The higher the intensity, the smaller the meal or the further out you want to eat," advises Mohr. You don't want your body to be expending any extra energy on digestion when you need it to perform.
"If you're going out for a 30-minute morning walk, you don't have to shove food in your mouth to fuel up," says Mohr.
A lower intensity workout doesn't require as much energy as a demanding one. For example, if you're planning on burning only 350 calories on the elliptical, a 200-calorie snack isn't needed. And, as a general rule, if you're going to exercise within a few hours of a meal, those are the times you may be better off skipping your pre-workout fare, says Sass.
3. Fuel up
So how should you pre-game for maximum performance? Two or three hours before a moderate intensity workout, a somewhat complex meal like a sandwich on whole grain bread with lean protein, roasted vegetables and avocado is a good option because "you'll have time for your food to get digested and absorbed from your GI tract into your blood," says Sass.
On the contrary, if you plan to do the same workout within one to two hours, a small bowl of low-fiber, whole-grain cereal like puffed brown rice or corn flakes with organic skim milk or a plant-based milk is ideal. The cereal will provide easy to digest calories for quick energy while the milk provides sustaining protein. Oatmeal with a banana will provide the same benefits, according to Mohr, for individuals looking for a simpler meal option.
Want something even easier? A quality nutrition bar (with ingredients you can pronounce) or homemade protein shake works wonders.
For workouts with an hour or less lead-time, smaller snacks like Greek yogurt or low-fat chocolate milk are good options. And, if you do happen to find yourself heading out the door as your stomach starts to rumble, you can't go wrong with a small piece of fruit, like an easy-to-digest banana.
Now that you know the perfect fuel formula, consider these delicious pre-workout snacks.