You probably have heard that some people perform cardiovascular exercises without eating anything first. But is it effective? It all comes down to individual differences in body type, objectives, health, and personal choice.

Fasted cardio has some benefits, including the potential to increase fat loss and the elimination of dyspepsia. On the flip side, some people may have decreased strength and energy levels during exercise, so it may not be a good choice for everyone.

Therefore, keep reading for the pros and cons of exercising while fasting and how intuitive eating can affect your performance and outcomes.

Understanding Fasted Cardio

“fasted cardio” refers to any type of exercise performed without first eating. It’s said you’re in a “fasted state” when you have gone four or more hours without eating, which is considered an extreme case of dieting.

There are certainly those in the fitness industry that subscribe to the idea that you can accelerate your fat loss by exercising before or after a fast. Still, it remains controversial and is not supported by any hard data.

Fasted cardio’s effectiveness is still debatable, and whether or not you choose to work out while fasting is a personal decision. Besides, you should be aware of some limitations to fasting cardio before committing.

What’s The Best Way to Perform Fasted Cardio?

The vast majority of fasting cardio practitioners get their workout in the morning, even before consuming anything. Therefore, aim for a 30-45 minute workout at a moderate level.

The United States Department of Health and Human Services recommends 150–300 minutes of moderate-intensity physical activity each week; shorter workouts can help achieve this goal.

How Effective Is Fasting Cardio?

What works for your body might not benefit your workout partner. But, if done correctly, fasting cardio can be quite beneficial. Fasting cardio may aid weight loss, forcing the body to rely on fat reserves for fuel instead of carbs. Without access to carbs, the body must find alternative fuel sources.

The theory is straightforward. The effectiveness of this strategy, however, is still up for debate. One study found no variation in body composition between fasting and fed exercise sessions, assuming the workouts were identical. On the other hand, new research reveals that fasting cardio can help you trim down.

Low hepatic glycogen and insulin levels have been linked to fasting. Hence, doing exercise at this time may help you use fat for energy. This signifies that stored fat is being utilized, or “burned,” and may lead to reduced body fat.

In most cases, a 30- to 60-minute session of steady-state exercises, like jogging, would be the best method to use fasting cardio. More intense workouts, such as lifting heavy barbells, usually necessitate more food and fluids to power the body.

You shouldn’t push yourself as hard or for as long as you would if you ate before your workout. The goal is to get the most out of your activities without risking your health by denying yourself nourishment or going beyond your physical limits.

Possible Advantages of Intermittent Fasting for Cardiovascular Health

In addition to the challenges of getting up and out the door for a morning workout, there is also the issue of food. Yet, there are other possible advantages of fasting cardio.

Here are some of the common benefits of fasted cardio:

Increase Fat Oxidation and Calorie Consumption

Some research suggests that the fast cardio plan can help manage weight loss. Compared to aerobic exercise done while fed, “aerobic exercise done while fasted generates higher fat oxidation,” as the authors of a meta-analysis published in 2016 wrote.

When there is no readily available glucose or glycogen during fasting, the body must rely on its energy reserve.

Image alt text: fasted cardio. A group of army official taking part in fasted cardio exercise to lose weight and stay fit.

Author credit: By Spc. Crystal Abbott /10th PCH – United States Army, Public Domain, https://commons.wikimedia.org/w/index.php?curid=8262170

To keep you going, your body will draw power from your muscle and fat stores (through fat lipolysis and oxidation). When energy needs rise dramatically, such as during prolonged periods of fasting or vigorous activity, the metabolic pathway known as lipolysis kicks in to convert triglycerides in lipids into the glycerol or fatty acids that the body can use.

This may increase your “fat-burning” capabilities, though the increase will probably be subtle. Fasted cardiovascular activity also helps manage unmonitored weight by increasing energy expenditure after exercise. The extra calories burned during recovery from a fasted workout can boost your metabolism over the next day.

If you eat anything, even a light snack, before exercising cardio, you may feel nauseous. This is common with breakfast items that are high in fat and fiber.

When the stress response occurs seldom, the body can recuperate and resume typical operation. However, the body has more difficulty recovering if the stress reaction is engaged too frequently.

This obstructs the digestive process and may lead to stomach distress. Furthermore, IBS and ulcers may form as a result of this. Simply put, too much mental or emotional strain interferes with digestion.

Therefore, if you can’t tolerate GI stress or have time to digest it for at least two hours, you might fare better with a quick-release energy source or by doing cardio while fasting.

Consequences of Cardiovascular Fasting

Fasting cardio has the potential to help you lose body fat, but there are several risks you should be aware of before giving it a try.

Increase Your Susceptibility to Fatigue or Tiredness

If fasting cardio makes you tired and uninterested, you may have to cut your workout short. Once more, it depends on the person.

Some studies have shown that fasting reduces performance, while others have shown that it increases endurance, while still others have shown no significant association or effects.

You won’t need breakfast if you plan to work out first thing in the morning after a good night’s rest. Nonetheless, fatigue may be an issue if you exercise late in the morning without eating anything after being up.

Thus, cardiovascular exercise endurance relies on various elements, such as the individual’s time constraints, physical makeup, and other characteristics.

May Speed Up Muscle Deterioration

Fasted training may harm muscle growth and strength, primarily overlooked in discussions on fasted aerobic exercises. Some research suggests that a fasting activity stunts endurance and strength gains because muscle tissue is broken down for energy.

Therefore, fasted aerobic activities may compromise the effectiveness of bodybuilding, cross-training, and weightlifting. And you should limit the frequency and intensity of your fasting cardio workouts.

Fasted Cardio Reduces Your Performance

Cardiovascular exercise performed while fasting has a deleterious effect on subsequent workouts. Sometimes this approach can be helpful, but it’s never a viable long-term solution. It may even work against you when trying to improve your performance or lose weight.

Fat burning has been demonstrated to reduce exercise intensity and duration, making it less desirable for longer, more excellent intense workouts. In this case, it may be more effective to undertake fasting cardio at a low to moderate intensity once or twice weekly to keep your performance and weight-loss plans on track.

Also, exercising on an empty stomach, which reduces insulin levels, is a common cause of fatigue. Because of this, it is essential to tune into your physical needs to develop exercise and diet plans for optimal heart health. You may find that your performance suffers, and your workout duration is drastically cut due to low energy.

Is Fasted Cardio Worth a Shot?

Although fasting cardio has been shown to increase fat loss, the overall energy flow and calorie intake are the most critical factors in determining whether you will succeed in your weight-loss endeavors.

But remember that if you exercise while fasting, you can feel more hungry than usual, which could lead to binge eating. Besides, eating a high-calorie meal after a fasting cardio session could help you accomplish your daily calorie goal. Still, it will only help you lose weight if you finish with a calorie balance for the day.

Conclusion

Fasted cardio training is something you can choose to do or not do. Regular exercise has obvious health advantages, including the potential for healthy, long-term weight loss, whether or not it is performed before eating. Start slowly and gradually increase the intensity if you’ve never worked out before breakfast before.

Therefore, allow your body time to adjust to your new exercise and diet routine. Experiment with different forms of physical activity until you find what you enjoy and what fits into your lifestyle.