Can you exercise on an empty stomach? Ultimately, it comes down to your body composition, goals, overall health, and preferences. Training on an empty stomach, also called “fasted cardio”, has some benefits, such as the possibility of losing more fat and avoiding indigestion during exercise. On the other hand, it is not suitable for everyone, as some may feel weaker and lethargic during exercise. If you’re curious about how meal timing can affect your training performance and results, read on to learn the pros and cons of fasted training.

What is Fasted Cardio?

Fasted cardio involves doing aerobic or endurance exercise on an empty stomach, without eating anything first. This is called being in a “fasting state”, meaning 4-6 hours after your last meal or snack. For you to be truly fasted, that is, to have your glycogen levels low, some experts say you need to go more than 9 to 10 hours without eating anything. Fats and carbohydrates are the most important fuel sources for skeletal muscle ATP synthesis, so when carbohydrates are not available due to fasting, fats are used instead. Most people do fasted cardio workouts in the morning before eating anything for breakfast. This can mean that a person has fasted for 8-16 hours or more overnight, depending on their schedule and when they stop eating in the evening. For many people, the morning is the easiest time to train without any “fuel” in their body, because they have just gotten up and have already fasted all night.

Health Benefits

What are the benefits of fasted cardio? Based on the available research, here’s what we know about the potential benefits of training without food in your body:

1. May Boost Fat Burning and Weight Loss

Is fasted cardio really effective for weight loss? Some studies suggest yes. Researchers involved in a 2016 meta-analysis concluded that “aerobic exercise performed in the fasted state induces higher fat oxidation than exercise performed in the fasted state. When you’re fasting, your body doesn’t have available glucose/glycogen to use as a quick source of energy, so it uses stored energy instead. This means that your body draws on stored energy from your muscles and stored body fat (via lipolysis and fat oxidation) to provide you with energy. Lipolysis is the metabolic pathway by which lipid triglycerides are broken down into fatty acids and glycerol for use during fasting or intense exercise. The result is that you can increase your “fat burning” potential, although the effect is not dramatic in most cases.

Another way fasted cardio can promote fat loss is by stimulating post-exercise calorie burning. Essentially, after you complete your fasted workout, your body uses extra calories to help you recover, which raises your metabolic rate a bit for about 24 hours. That being said, not all studies have found this benefit. A 2020 article published in the Open Access Journal of Sports Medicine states that “Our review of the literature suggests that there is little evidence to support the notion of endurance training and increased mediated fat oxidation. by fasting, and we recommend that endurance athletes avoid high intensity training while fasting. »

The researchers add that…

Fasting decreases body weight, lean body mass, and fat content in trained and untrained individuals…However, there are conflicting data regarding the effects of fasting on glucose metabolism in highly trained athletes…Differences in the Experimental design, severity of caloric restriction, duration, and participant characteristics could, at least in part, explain these discordant results.

2. May Decrease Nausea

If you find it difficult to feel nauseous when you exercise, is it good to train in the morning on an empty stomach? It’s possible, assuming a full or partially full stomach is the cause of your indigestion. If eating before doing cardio makes you uncomfortable, you can try not eating anything before and maybe drinking some water or coffee. If you find that the feeling of “lightness” in your stomach is better during exercise, then fasted cardio might be right for you. Everyone is a little different when it comes to their food preferences heading into a workout; some like to have a small snack before training, others prefer a larger meal a few hours before training, and still others prefer to eat nothing at all. Feel free to experiment and see what works best for you.


1. You might feel tired more easily

Fasted cardio may shorten your workout if you feel fatigued and unmotivated more easily. Again, it depends on each individual. Overall, the effects of fasting on physical performance remain unclear, with some studies reporting a decrease in performance, others an increase in endurance, and still others reporting no correlation or effect. significant.
If you wake up early for a workout after a good night’s sleep, you may have plenty of energy even without a meal. On the other hand, if you train later in the morning on an empty stomach, after spending several hours on your feet, fatigue can be a problem. So it seems to depend on your schedule, body type, and other factors.

2. May cause weakness and decrease in power output

Some find that fasted cardio causes side effects such as dizziness, hypoglycemia, and lightheadedness. You may not be able to push yourself as hard when you are fasting because you feel weak, in which case you reduce your physical performance. For example, one study concluded that “overnight fasting compromises exercise intensity and volume during sprint interval training, but improves high-intensity aerobic endurance. Another meta-analysis found results indicating that pre-exercise diet improved performance of prolonged aerobic exercise, but not short-duration exercise. If you tend to feel sluggish when you’re out of breath during a workout, consuming a snack and water to stay hydrated before your workout may be a better solution than not doing it altogether. of food.

3. May Contribute to Muscle Breakdown

While we’ve mostly talked about fasted aerobics workouts, it’s important to point out that exercising on an empty stomach can have a negative impact on muscle growth and strength. Some studies have shown that fasted workouts cause muscle tissue to be broken down for energy, making it harder to gain muscle and develop strength and endurance.
If you’re into strength training, cross-training, and weightlifting, then fasting aerobics might be detrimental to your results. It’s not a deal breaker, but you should pay attention to the frequency and intensity of your fasted cardio sessions.

Should you try it?

In the end, is fasted cardio better than regular cardio?

As you’ve probably figured out, one approach isn’t necessarily better than the other. While fasted cardio may have some benefits for amplifying fat loss, if weight loss is your primary goal, your total energy balance and calorie intake will be the determining factors in your weight loss.

Remember that you may experience an increased appetite after exercising on an empty stomach, which can cause you to overeat later on if you’re not careful. If eating a calorie-dense meal after a fasted cardio session gives you a positive energy/calorie balance at the end of the day, it won’t help you achieve your weight loss goals.

Here are some things to consider if you want to try fasted cardio:

How long should you do fasted cardio?

Experts tell us that it’s probably best to stick to moderate-intensity cardio for no more than an hour on an empty stomach. However, if you personally have the energy to do even more without experiencing negative side effects, a longer or high-intensity workout may also be appropriate. It’s probably best to start with 20-30 minutes of exercise on an empty stomach, then increase the intensity and duration as you feel well. Listen to your body and avoid going overboard so that you feel dizzy or hungry.

What should you eat after fasting cardio?

You need to fill up on protein and complex carbohydrates, which will help you refuel and promote muscle recovery. Fiber and healthy fats are also important parts of a healthy meal after exercise, as they will help control your appetite and prevent you from overeating. Here are some examples of good recovery meals after exercise: a protein smoothie with fruit, hemp seeds and coconut milk; a salad with protein and avocado; quinoa with boiled eggs and vegetables; a sandwich with meat/fish/eggs and a side salad seasoned with olive oil.

Can we drink coffee before doing cardio on an empty stomach?

Most people find that coffee consumed in the morning before working out gives them a welcome energy boost that helps them see through their workout. As long as you also drink water to avoid dehydration and don’t feel jittery or nauseous after consuming coffee, this seems like a good option.

Should you combine intermittent fasting and exercise on an empty stomach in the morning?

This can be a good strategy if you already practice intermittent fasting (IF). People who incorporate intermittent fasting into their routine likely have more opportunity to exercise on an empty stomach since they skip meals anyway, most often breakfast in the morning. You’ll need to listen to your body and pay attention to weaknesses and other warning signs, but as long as you feel good about combining these two approaches, there’s no reason not to.

Final Thoughts

What is Fasted Cardio? This is another way of describing fasted training. Most often people do this in the morning after fasting for more than 8 hours. The potential benefits of fasted cardio are increased fat burning, aid in weight loss, and decreased indigestion. However, downsides can include increased fatigue and weakness during exercise, and increased appetite once the workout is over. Does it work for losing weight? It’s possible, but weight loss really depends on the person’s overall day and their energy/calorie balance. A fasted workout can slightly boost calorie and fat burning, but to lose weight, a person still needs to consume fewer calories than their body uses each day.

* criptom strives to transmit health knowledge in a language accessible to all. In NO CASE, the information given can not replace the opinion of a health professional.