Whether you’re trying to lose weight, maximize your athleticism, or improve your overall fitness, cardio exercises should be a big part of your workout routine. But if you’re looking to increase the efficiency of your cardio, you may be wondering if there’s an ideal time to get your cardio in.
You may have heard that it’s best to do your cardio on an empty stomach, aka “fasted cardio.” Here’s everything you need to know about doing cardio on an empty stomach: how it works, its benefits and downsides, and whether or not it can really maximize your caloric burn.
What Fasted Cardio?
A cardio workout refers to workouts that significantly increase your heart rate and respiration. “Cardio” is short for cardiovascular, referring to your heart, and generally involves the movement of your entire body. As your major muscle groups work hard during the exercise, they need more oxygen, which means that your heart has to work harder to pump enough blood, supplying the needed oxygen to all those hard working muscles. Things like running, jogging, swimming, and cycling are all classic examples of cardio activities.
So as the name suggests, fasted cardio workouts involve doing those workouts while in a “fasted” state — in other words, while on an empty stomach. For most people, this usually means performing that workout first thing in the morning, though you can also be considered to be in a fasted state if you haven’t eaten in a couple of hours.
Does Cardio On An Empty Stomach Help You With Your Fitness Goals?
So why would you choose to do cardio on an empty stomach in the first place?
The first answer is simple: convenience. Putting in work first thing in the morning gets your workout checked off of your list of “to-dos” quickly and leaves the rest of your day free to pursue all your other ventures.
But many people choose to do their cardio on an empty stomach for more than just scheduling purposes. One of the key reasons that many people schedule their cardio first thing in the morning is because of the idea that it might maximize their fat burn and weight loss.
To understand this, you should have a basic understanding of how fat loss works. It’s largely dependent on calories, which are the units of energy that you get from the foods you eat, in turn, helping your body function properly. You need calories for all the little things that your body does to keep you alive, like breathing, digestion, and thinking, plus you burn more calories the more active you are.
The general idea behind weight management is that, when you eat more calories than you use, your body stores those extra units of energy as fat. If you eat fewer calories than you use, your body turns to those stored energy units in your fat tissue and “burns” it, leading to weight loss.
So cardio, requiring a large number of calories to fuel the workout, is one of the biggest tools that you can use to lose weight. The idea behind fasted cardio is that you don’t have any food in your system that your body can quickly access your fuel, which means that it has to start burning your stored fat instead.
Whether or not this actually works, though, is still hotly debated. According to Healthline, some studies have found that cardio in a fasted state can increase your fat burn, while others have shown that there isn’t too much of a difference in fat burn between people who are fed vs. fasted.
So what we do know is that regular cardiovascular activity is a good way to lose weight, and doing it first thing in the morning may be more convenient than doing it at other times of the day — but there isn’t enough scientific evidence as of now to prove that it’s a better way to burn calories.
Is It Safe To Do Cardio On An Empty Stomach?
Doing your cardio on an empty stomach can also bring up questions as to whether or not it’s a safe practice. The answer to this will largely depend on your current fitness level and the kinds of exercises that you’re doing.
Doing fasted cardio is generally safe if you plan on doing your exercise at a low or moderate intensity. But if you’re doing a long and/or intense cardio workout on an empty stomach, it may lead to low blood sugar levels, which could be dangerous and present in symptoms like headaches, dizziness, shakiness, and fatigue.
In addition, you may not want to rely on fasted cardio if you’re trying to build or maintain muscle. In the absence of other sources of fuel, your body may also start to burn the protein stored in your muscles to sustain you through your workout. This lack of protein can interfere with your muscles’ ability to recover and grow after a workout, ultimately leading to depleted muscle mass.
And remember, food is fuel. You won’t be able to go all out during a really hard workout if you don’t have any fuel in the tank, which could be bad news for your training progression.
What Kinds Of Cardio Should I Do On An Empty Stomach?
If you decide to do your cardio on an empty stomach, it might be better to do moderate-intensity cardio rather than high-intensity like HIIT.
High-intensity workouts like high-intensity interval training (HIIT) have become popular because of how efficient they are at helping you burn calories. But in order to do them well, you need a ton of energy. Your body will be relying on your stored energy sources for fuel when you’re doing such a heavy workout, and this can lead to muscle breakdown in addition to fat. This could be bad for your metabolism and bad for your physique. Ultimately, it may not help you reach your goals safely and efficiently.
But there are plenty of other more moderate cardio options that could be a great option for fasted cardio! Some good workouts that help you burn calories safely while in a fasted state include:
To test how intense your cardio workout is, you can try the “talking test”. If you can hold a conversation during your workout, it’s probably safe. If you’re gasping for breath and unable to hold a normal conversation, it’s usually safe to assume that your workout is a bit more intense.
Duration also matters. If you’re going to be working out for longer than an hour or so, you’ll want to have enough fuel to sustain the entire workout.
So to sum it up, if your cardio of choice is an intense yoga session or a moderate-intensity cycling circuit, cardio on an empty stomach could be a great choice! But if you prefer to do high-intensity interval training to get your burn on, you may want to hold off until a couple of hours after eating a good nutritious meal.
Whether or not you work out on an empty stomach can very often be chalked down to convenience, personal goals, and the type of cardio you prefer to do. It’s not necessarily a better way to do your cardio workouts – the important thing is to make sure you’re doing your cardio in the first place!