Depending on your fitness level and workout intensity, you burn primarily fat and carbohydrate during exercise. The human body stores both of these fuel sources, and we can tap into these for energy during exercise. For this reason, it is usually not necessary to eat before a short cardio workout.
Other factors for determining if you should eat before a cardio workout can include your current hunger level, your exercise intensity and exercise duration.
Timing your meals during the day
You can time your exercise around your meals so that you are nourished for your workout and don’t have to worry about eating something right before you work out.
Some people can eat a full meal and exercise 20-30 minutes later with no problem. On the contrary, other people need 2-3 hours after eating a meal before they can exercise comfortably.
If you are just starting to exercise, it may take some time to learn what your gastrointestinal system is most comfortable with for timing your meals and workouts.
If you can exercise in between breakfast and lunch or lunch and dinner, there is really no need to eat something additional before you do a cardio workout.
Planning your cardio workout right before your next meal is also common; you should have adequate energy from your previous meal.
Exercise in the morning
A common question is if you work out in the morning, should you eat something before you exercise? This is a different scenario than working out other times of the day because you are waking up from 6-9 hours of not eating.
Your glycogen stores (stored carbohydrate) are mostly depleted by the time you wake up, unlike at other times of the day.
Most traditional sports nutrition advice is to try to eat a little something before you exercise in the morning. This way your body will have some extra carbohydrate, and you will probably get a better workout because of this.
However, some research studies have shown there may be benefit to exercising before you eat something in the morning, especially if you eat a high fat diet.
A 2010 study from The Journal of Physiology found that males who exercised before breakfast burned fat more efficiently compared to a group of men who ate before exercising.
Both groups had the same type of high fat diet and equal calorie amounts.
What’s your goal?
Is it always best to exercise without eating in the morning? It may depend on your work out goal. If you are doing a speed workout or trying to do some high intensity intervals in the morning, it may be advantageous to eat something before you do your cardio.
Muscles primarily use carbohydrate as a fuel source for high intensity exercise. Since your glycogen levels are low when you first get up from sleeping all night, you may be able to push yourself more in your workout if you have some extra energy before your workout.
If you are staying in a more moderate exercise intensity, you probably won’t feel the effects of not eating anything before your workout.
The same guide can be true throughout the day: if you are feeling hungry and low energy before you exercise, you may be able to push yourself more in your workout if you eat a little bit before.
When do I need to eat before a cardio workout?
As mentioned, if you are doing a speed workout or higher intensity interval workout in the morning, you may want to eat something light beforehand. That way you may be able to go faster than you could without extra carbohydrate fuel.
If you are exercising for longer than 90-120 minutes, you will probably need to eat something before your work out if it is in the morning.
If it is during the day or evening, you should have adequate fuel stored in your body if you ate proper meals. However, you may need to take in extra calories, like sports drink, during your exercise for longer duration exercise.
Quick fuel options before a cardio workout
If you are hungry or want to eat something before your workout, what should you eat?
Everyone is different in terms of what their stomach can handle before exercise. Common light snacks before exercise can include a piece of fruit like a banana (avoid high fiber choices), half to a full energy bar, small handful of trail mix or half a sandwich.
In general, you don’t need to eat something before a short cardio workout. Your stored sources of carbohydrate and fat are more than adequate to fuel a workout session.
You can work out in the morning before eating, but note that if you are doing a speed workout or high intensity exercise you may feel sluggish.
You may be able to reach a higher intensity if you have eat something light beforehand to give you an additional carbohydrate source.