This type of workout may cause your body to turn to stored fat for energy to achieve changes in your body composition.
What Is Fasted
Cardio?
Fasted cardio consists of performing cardio exercise without the previous ingestion of any food. It is usually performed in the morning after a fasting period of the last 6-10 hours. While some people rely on fasted cardio for fat loss, others find it more difficult.
Below, we'll look at the evidence for and against fasted cardio, allowing you to decide if it's worth a try.
Why Does Fasted
Cardio Burn Fat?
Carbohydrates are the body's main source of fuel during exercise. After carbohydrate intake, glucose (building blocks of carbohydrates) is available to the body in the bloodstream and energy muscles.
A long, intense cardio session burns the available glucose and then begins to burn stored energy (muscle glycogen).
Weight is lost when more calories are burned than consumed, which is why we do cardio. However, focusing on burning fat instead of carbohydrates (the body's preferred energy source) can be tricky.
The fasted cardio theory says to work at a less intense level so that when glucose is not readily available to the body, it begins to break down stored fat for energy. It can be difficult to get the balance right so that the body burns stored fat as a fuel source rather than stored muscle glycogen.
What Are the
Benefits of Fasted Cardio?
1. Helps Burn Stored
Fat - The Source of Energy
Normally, people decide to try fasted cardio because exercising without having previously consumed food forces the metabolism to adapt. However, the type of exercise and intensity also affect how the body decides to fuel your workouts.
Ideal conditions for fat burning include not having consumed glucose (fasting for the last 4-8 hours) and not training at an intensity high enough to damage/degrade muscle tissue.
2. It Is
Complemented by Intermittent Fasting.
If you do intermittent fasting, which is having a limited time per day to consume food, you will most likely train in the morning during the fast. Although there are many types of intermittent fasting and research on its benefits and side effects, fasted cardio complements well with this type of diet.
3. You Can Do
It Right When You Wake Up
One of the best benefits of fasted cardio is that you can save time eating before training. As a general rule, you should wait about 30 minutes after food intake before starting your workout. This means that if you have to train at 06:00 in the morning, you have to finish eating at 05:30 and wait until 06:00 to train.
Thanks to fasted cardio, you don't have to worry about getting up earlier to eat, not even a protein shake. You get up, train, and eat when you finish training.
Fasted Cardio for
Fat Loss/Weight Loss
So, does it work for weight and fat loss? As with many other strategies in bodybuilding and sports in general, it depends. Although research supports the idea that you burn more fat without carbohydrates in your digestive system, it can be tricky to have enough energy to get through your running, cycling, or elliptical workout.
If your goal is to push yourself to the max or perform long, intense aerobic workouts, your body may not function optimally if it focuses on breaking down fat for energy. Besides, this can lead to muscle breakdown.
If, on the other hand, you perform aerobic exercise at a low to moderate intensity, fasted cardio will only be a minor readjustment to your day-to-day. You can do it even if you are one of those people who find it hard to get out of bed early, simply by doing cardio 6 hours after your last meal, for example, between the midday meal and dinner.
As long as the pre-workout meal has been digested and absorbed, insulin and blood glucose levels should be low enough that the body is forced to draw on fat energy stores.
Studies have shown that regular fasted training allows the body to increase its efficiency in burning fat for fuel over the long term.2 If cells do not have glucose to get the energy they need, they must adapt to get it by another means. This means that they will use fat as an energy source as long as you train at the right aerobic intensity.
Is Fasted
Cardio Safe?
In general, unless you have blood sugar control issues that would make exercising without eating beforehand unsafe, fasted cardio at a medium-low intensity is safe for most people.
Typically, most training plans have light cardio days known as "active rest" or "active recovery," which is a good opportunity to try fasted cardio.
On the other hand, if what you want to do is HIIT (high-intensity interval training), long-distance running, swimming, or bike racing, it's best to schedule these types of workouts at times with proper nutrition.
Typically, these types of intense workouts require additional nutrition during their execution, in addition to a pre-workout meal high in carbohydrates. Long-duration aerobic exercise places such high demands on the muscles that they need glucose (carbohydrates) and stored energy (in the form of glycogen), which must come from proper nutrition in the days and weeks before the training.
Research has shown that proper pre-workout nutrition is key to optimizing performance in weightlifting and other short, high-intensity workouts.
Suppose you exceed the recommended low intensity (approximately 50-60% of your maximum heart rate) while doing fasted cardio. In that case, you run the risk of burning muscle instead of fat during the workout, plus you may not be able to perform the workout properly.
Is Fasted
Cardio Right for Me?
How can you assess if it's right for you? If you are trying to achieve changes in your body composition or want to lose those last few extra pounds, it may be a good time to give it a try.
In addition to your daily workouts, adding fasted cardio to your daily routine at a low to medium intensity could be the push you need to get results.
As with any training, keep track of how you feel during and after your workout so you can adapt and discover what works best for you.
Gentler exercises that slightly increase your heart rate are the best choices for fasted cardio, such as gentle elliptical, yoga, pilates, gentle cycling, or a light jog. More intense workouts exceed the proper heart rate for fat burning and lead to dizziness or weakness without a meal beforehand.
When might fasted cardio not be recommended for you? Anyone with blood sugar control (diabetes or hypoglycemia) or who has to eat first thing in the morning due to any other medical condition should talk to their doctor before doing fasted cardio.
If you feel hungry for the rest of the day after fasted cardio, you could end up overeating, and all your hard work will be for nothing. Some studies found that subjects were unsuccessful for this very reason. The timing and type of food you eat after training can help you avoid this, so choose foods high in protein and fiber to feel more satiated.
Normally, burning fat for energy without consuming carbohydrates can lead to a desire for a higher caloric intake to replenish, so you'll need to choose your post-workout meal carefully (and quickly) and get your nutrition right for the rest of the day. Be sure to consume plenty of protein if your muscles are overly stressed due to fasted cardio exercise.
When
to Use Fasted Cardio
Fasted cardio is a pretty exciting protocol and one that has its place in fat loss planning. However, it is a measure that, in my opinion, is entirely unnecessary, especially in the early stages of a definition phase.
When considering a definition period, the most essential variable is the caloric deficit, and obtaining it can be done either through diet (fewer calories) or through exercise (more energy expenditure). Either of these two measures will work and help you lose fat.
Once your fat loss phase is more advanced, you will find that it is more challenging to keep moving forward and fat burning becomes more complicated. This is because you have already gotten rid of the "easy" fat, the fat from the body parts that have more beta-2 receptors and therefore easier to mobilize.
At this point, you have to deal with your stubborn fat that does not respond as well to conventional measures and is more difficult to mobilize.
This is where fasted cardio would come into play by favoring the mobilization of this type of fat.
You could indeed start using the fasted cardio protocol from minute 1 of your definition; however, the problem with low-intensity cardio exercise is that the body becomes increasingly efficient and more tolerant to it, so the more you practice it, the longer you will have to subject the body to that activity to burn the same amount of fat.
That is why I advise using cardio exercise in general in moderation and specifically fasted cardio to fight that stubborn fat that is so hard to get rid of. Still, until you are in a condition to deal with this type of fat, it is preferable not to exercise on an empty stomach.
Conclusion
Whether you do the cardio on an empty stomach or with a meal beforehand, the key to burning fat and losing weight is a caloric deficit. If you have enough time and commitment to add a few days of low-intensity fasted training, it's worth a try.
Fasted cardio can be the push you need to get better results from your workouts. But, make sure you don't overeat to compensate for your workout.