Nutrition / Food

Should I Eat Before a Cardio Workout?

To eat or not to eat before a cardio workout—that is the question. We've got the answer.

Navigating the maze of nutrition advice about when and what to eat for a cardio workout—whether you’re doing a treadmill cardio workout to build endurance or an elliptical workout to lose weight—can make your head spin.

When it comes to eating before cardio, for every person who swears by exercising on an empty stomach, there’s another who says to always eat a small snack first.

Related: Aaptiv has the best cardio workouts. Find out the best ones with our 2 minute fitness quiz.

Experts may sing the praises of protein shakes while a blogger might opt for “real” food . We consulted registered dietitian Sara Monk to help you decipher what’s true, what’s false, and what’s best for you when it comes to fueling up for cardio fitness.

FALSE: Carbs, carbs, carbs before exercise.

Always eat a balance of real food carbohydrates, protein, and healthy fats before a cardio workout. If you’ve heard from your favorite fitness gurus that all you need before your workouts are carbs—a piece of fruit, oatmeal, or a granola bar—it’s time to throw that idea out the window. Evidenced-based studies indicate this information is outdated. In fact, it has scientifically proven wrong. Instead, make sure what you eat is a balance of good carbs, protein, and healthy fats. The protein and healthy fats are crucial because they slow down the absorption of carbohydrates. Even the best carbs turn directly into sugar in your body. Avoiding eating solely carbs means you won’t have a sugar crash that’ll leave you feeling exhausted 15 minutes into your workout.

Looking for new workouts? Aaptiv has you covered… learn more here.

FALSE: Working out on an empty stomach burns more calories.

First, you have to understand what is occurring in your body when you do a cardio workout on an empty stomach (known as fasted cardio). Carbohydrates turn into glucose, more commonly known as sugar, in the bloodstream. Glycogen, which is a stored form of glucose, “runs out” when you sleep. When you wake up, skip breakfast, and hit the gym, your body is low in carbohydrates so instead it burns fat for energy.

When you wake up, skip breakfast, and hit the gym, your body is low in carbohydrates, so it burns fat for energy.

A benefit of fasted cardio is that you burn more body fat during a workout. Your body gets used to being in a fat-burning mode, especially if you limit your carb intake throughout the rest of the day. If you don’t have carbs in your body, it has no choice but to burn fat for energy. So, if you’re hoping for fat loss, it may be beneficial to incorporate a few fasted cardio sessions into your routine.

If you won’t try to make up for the calories you didn’t eat for breakfast later on in the day and can successfully get through your workout—then this option may be for you! Be sure to check with your doctor first, because some health conditions (such as diabetes) are not a good fit for this type of approach. Start with a light cardio workout before going all out. Always remember to listen to your body and do what works for you.

FALSE: You have to eat two hours before or after a workout.

Aim to fit in your pre-cardio workout meal about 30-60 minutes before you exercise. Timing is just as important as food choice in keeping you energized throughout your workout. You should eat 30-60 minutes prior to your workout to allow the food to digest, and wait about 30-45 minutes to continue the fat-burning wave after. Note that waiting too long to eat after can slow down your metabolism and drop your blood sugar levels.

When it comes to eating after cardio, a great post-cardio workout choice is a protein with a veggie carb, like a spinach salad with grilled chicken or a piece of salmon with mixed veggies. If you’re lifting weights, it’s important to eat shortly after in order to replenish your glycogen levels, raise your blood sugar levels and bring in amino acids and other nutrients to aid in repairing the muscle fibers you just broke down. (Tip: save your protein shakes for these days.)

FALSE: If food is healthy, then you should eat as much as you want.

Portion sizes matter most when it comes to boosting energy for a workout. In order to prevent energy loss during your workouts, you must consume energy-boosting, nutrient-dense foods. Don’t get caught up in the ratio of protein, fat, and carbs. Instead, understand portion sizes.

Protein portion sizes should be 3-5 oz. That would be 2-3 eggs and ½ cup cheese. Fat portion sizes should be at least 10g per servings; for example, as 1 tablespoon of butter or oil, 2 tablespoons nut butter, 16 nuts, and 2 tablespoons of seeds. Carbs have two forms: non-starchy and starchy. For non-starchy veggies, such as spinach, tomatoes, kale, mushrooms, and onions, you should have 1-3 cups per serving (more if you’d like, they’re full of nutrients and low in calories). For starchy carbs, such as potatoes, oats, quinoa, chickpeas, and most fruit, stick to ½ cup per serving.

FALSE: Count all the calories.

Focus on whole foods. Don’t get too nit-picky with counting calories and paying attention to macronutrient ratios. Be sure to eat from whole, high-quality food sources to keep your blood sugar stable and burn fat during a workout. Tweaking recommendations to your liking, and to your benefit, is encouraged. Find what works best for you.

Still wondering “what should I eat?” Here are some examples of pre-workout or pre-cardio snacks that will not only keep you energized throughout your workout but aid in muscle recovery and lean muscle growth:

Now that we’ve broken down these popular myths, eat up for your best cardio workout yet!

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