You may have noticed a heart rate zone on the console if you frequently use a cardio machine. The chart outlines different heart ranges for your fitness routine depending on your end goal, be it increasing your cardio endurance or burning fat. One of the zones is called the fat-burning zone.
It shows you at what heart rate you burn more fat than glycogen. This zone is often misunderstood as it is a little more complicated than this. We explore cardio versus fat burning exercises and which of the two is better for higher calorie expenditure.
What Is Cardio?
Cardio, also known as aerobic exercise, is any activity that increases your heart rate and respiration and increases oxygen and blood flow throughout the body. Cardio creates an energy demand on your system to raise your heart rate and circulation. Some of the common examples of cardio exercises include swimming, running, hiking, and cycling.
Unlike other forms of exercise, cardio relies on the body’s ability to expend oxygen during a workout session. During a cardio workout, your respiratory system starts to work harder as your breathing becomes faster and deeper. Your blood vessels then expand to carry more oxygen to your muscles, and the body releases endorphins.
Cardiovascular training is good for your heart. Research indicates that regular cardio can help prevent cardiovascular disease (2). Cardio also helps boost your mood because of the production of endorphins. It is also a great weight loss exercise.
Does cardio burn fat? How much cardio to lose weight do you need to do?
The best cardio for weight loss includes rope jumping, cycling, and high-intensity interval training. You need to do about 150 to 300 minutes of moderate cardio and 75 to 150 minutes of high-intensity aerobic activity weekly.
Read More: Cardio Fat Burning Zone For Weight Loss Explained
What’s The Fat Burning Zone?
You probably have heard about the fat-burning zone, but is it true it helps you burn the most fat? What is the heart rate for fat burn? The fat-burning zone refers to working at about 55 to 70% of your maximum heart rate. You, therefore, work out at a lower intensity to stay within this zone.
The muscles and other body tissue require glucose as a fuel to perform life-supporting functions. The two primary energy sources for the body are glycogen and fat, which break down to give glucose. Oxygen is required to break down (oxidize) glycogen or fat to form glucose to fuel muscles during a workout. Through several biological processes, cells convert either fat or glycogen into the usable form of ATP (adenosine triphosphate).
During exercise, the body requires more energy. In response, the heart pumps harder and faster to send more oxygen into the muscle cells to oxidize more glycogen and fat to fuel the muscles. Glycogen is, however, a less dense energy source and is readily oxidized to glucose compared to fats.
During high intensity, energy is required more quickly. Thus, glycogen is the body’s first source of fuel during exercise. The body only uses fat when the glycogen stores start to become depleted.
The fat-burning zone theory seeks to promote weight loss by tapping into the body’s fat stores rather than glycogen. It is believed that the body burns more fat during a lower intensity workout than at higher intensities as the body does not need ‘fast energy’ from glycogen. As a result, you need longer, lower-intensity cardio exercises that keep your heart rate within the fat-burning zone.
When the body is at rest, and the breathing rate is normal, oxygen is readily available and slowly metabolizes fat. In homeostasis, therefore, the body uses the most abundant energy source in the body, fat. Similarly, when exercising at lower or moderate intensities, the body utilizes fat, the slow-burning energy, to fuel the muscles.
This is, however, a misconception. Much as it is true that the body burns fat when exercising at lower intensities, the fat burning rate is low. You, therefore, have to work out for prolonged periods to burn the same number of calories you would during vigorous aerobic activity.
Fat loss is an essential part of weight loss. After you eat a meal and the food is absorbed, glucose is released into the bloodstream. This stimulates the pancreas to release insulin. Insulin acts on many cells in the body, particularly those in the liver.
Insulin stimulates muscle and fat cells to absorb glucose and inhibits the conversion of glucose into glycogen. You probably have heard about the fat-burning zone, but is it true that it helps you burn the most fat? What is the heart rate for the fat burn? The fat-burning zone refers to working at about 55 to 70% of your maximum heart rate. You, therefore, work out at a lower intensity to stay within this zone.
The muscles and other body tissue require glucose as a fuel to perform life-supporting functions. The two primary energy sources for the body are glycogen and fat, which break down to give glucose. Oxygen is required to break down (oxidize) glycogen or fat to form glucose to fuel muscles during a workout. Through several biological processes, cells convert either fat or glycogen into the usable form of ATP (adenosine triphosphate).
During exercise, the body requires more energy. In response, the heart pumps harder and faster to send more oxygen into the muscle cells to oxidize more glycogen and fat to fuel the muscles. Glycogen is, however, a less dense energy source and is readily oxidized to glucose compared to fats.
During high intensity, energy is required more quickly. Thus, glycogen is the body’s first source of fuel during exercise. The body only uses fat when the glycogen stores start to become depleted.
The fat-burning zone theory seeks to promote weight loss by tapping into the body’s fat stores rather than glycogen. It is believed that the body burns more fat during a lower intensity workout than at higher intensities as the body does not need “fast energy” from glycogen. As a result, you need longer, lower-intensity cardio exercises that keep your heart rate within the fat-burning zone.
When the body is at rest, and the breathing rate is normal, oxygen is readily available and slowly metabolizes fat. In homeostasis, therefore, the body uses the most abundant energy source in the body, fat. Similarly, when exercising at lower or moderate intensities, the body utilizes fat, the slow-burning energy, to fuel the muscles.
This is, however, a misconception. Much as it is true that the body burns fat when exercising at lower intensities, the fat burning rate is low. You, therefore, have to work out for prolonged periods to burn the same number of calories you would during vigorous aerobic activity.
Fat loss is an essential part of weight loss. After you eat a meal and the food is absorbed, glucose is released into the bloodstream. This stimulates the pancreas to release insulin. Insulin acts on many cells in the body, particularly those in the liver.
Insulin stimulates muscle and fat cells to absorb glucose and inhibits the conversion of glucose into glycogen. The cells obtain energy from glucose. The excess glucose is then stored as fat (4).
Lipogenesis takes place in the liver, where protein and carbs can be converted into fats. The glycogen stored in the liver and muscles can be converted into fat in the liver and stored in the form of triglycerides. They are then transferred into adipose tissue for storage (3).
Fat cells (adipocytes) exist to store energy. The body expands the number and the size of fat cells to accommodate extra energy from high-calorie foods. Fat is stored under the skin (subcutaneous fat) and in areas such as the abdomen (visceral fat). A high amount of body fat, especially visceral fat, can increase the risk of certain diseases (1).
Adipose tissue is a loose connective tissue that is responsible for storing fat in the form of lipids. It is made up of adipocytes, and it insulates and cushions the body. Fats are a type of lipid stored in adipose tissue.
The physiological process of fat burning occurs when fats are released from adipocytes into body circulation to provide the required energy. The human body needs food to enable its cells to perform life-sustaining functions. The term fat burner is often used to describe nutritional supplements such as caffeine, chromium, and carnitine that impair fat absorption, increase fat metabolism,fat-burning, and fat oxidation during exercise (5).
The fat-burning process is complex, and unlike what many may think, the body does not lose fat cells during this process. The fat cells stay where they are in the hips, thighs, or on top of muscles, and that is why it’s impossible to see defined muscles when you have excess body fat. Instead, the body empties the fat in the fat cells as fat is like an energy reserve and the adipocytes like a storage unit.
When you begin a regular workout regimen and limit your calorie intake, the body uses the energy stored in the fat cells to perform different functions. As a result, the body also stops storing too much fat in the adipose tissues. The fat stored in the form of triacylglycerol is not burned within the fat cell but first liberated through complex enzymatic and hormonal pathways.
On stimulation, fat cells release triglycerides into the bloodstream as free fatty acids (FFAs). The free fatty acids are then transported via the blood to the cells and tissues where the energy is required. The lungs, heart, muscles, and other tissues then pick up these free fatty acids.
Each triacylglycerol molecule is split into glycerol and three fatty acids through a process known as lipolysis. The reaction is catalyzed by hormone-sensitive lipase. The free fatty acids then enter the mitochondria by lipoprotein lipase activity, and this is where the FFAs are burned.
After the fats are liberated from the fat cells, it shrinks in size. This is why the body looks leaner when the body loses fat after regular exercise and healthy eating since the fat cells are smaller. Fat cells shrink or expand in size based on how they are filled. So, over time, the size of fat cells reduces, and the baseline metabolism increases (6).
Too much visceral fat leads to obesity, increasing the risk of heart disease, diabetes, and hypertension. It is important to note that too little adipose tissue can also cause severe health conditions. Not eating often enough leads to losing a dangerous amount of weight.
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Fat Burning Versus Cardio Exercise: Which Is The Best?
Individuals often exercise to lose weight, build muscle, keep fit and tone their bodies. However, how fast or slow you lose weight depends on the type and intensity of exercise, diet, and other factors, including your sleep and stress levels.
The general rule in weight loss is burning more calories than you consume. This is often done by creating a calorie deficit. To lose weight, you need to increase your physical activity and reduce your calorie intake.
Heart rate is a measure of how intensely your heart is working helps determine the intensity of physical activity. When you exercise at high intensity, you prompt your heart to beat faster to circulate more oxygen to oxidize different energy sources. Therefore, it is only natural that individuals trying to lose weight will try to exercise at an intensity that keeps their heart rate within the fat-burning zone.
According to the American Council on Exercise, a heart rate that improves cardiovascular fitness falls between 55 to 80% of the maximum heart rate. Athletes and individuals trying to lose weight may benefit more from working out at higher intensities. Note that your maximum heart rate depends on age, as your heart starts to beat slower as you age.
The fat-burning zone occurs between 55 to 70% of your maximum heart rate. On the other hand, the cardio zone occurs between 70 to 85% of your maximum heart rate. When you exercise at higher intensities, you burn more calories.
At the cardio zone, where you exercise at higher intensity, your body first uses your glycogen stores to fuel your muscles. Afterward, your body taps into your fat stores to provide energy. With cardio exercises, your body works your muscles enough to deplete your glycogen and tap into your fat stores.
High-intensity workouts force the cardiovascular and respiratory systems to work faster and harder to keep you moving at intense levels. The heart contracts more quickly to pump and supply oxygenated blood to the working muscles. Your lungs also work faster so that you can breathe at a rapid pace. Any time the tissues and organs work harder than normal, it requires more calories.
But between fat burning versus cardio exercise, which is better? Exercising within the fat-burning zone uses your fat stores to provide fuel. The downside is that the fat-burning process is slow. So if you stick to low to moderate-intensity exercise to stay within this zone, you end up burning fewer calories.
Of course, when thinking about the fat burning versus cardio heart rate, the cardio heart rate is higher, and your heart and lungs work at a faster pace. With cardio, you increase your workout intensity. So much as you use glycogen, the “fast energy” is first to fuel the active muscles, and you burn more calories. As a result, you lose more weight.
To determine the better option between cardio versus fat-burning zone, you also need to factor in how long you need to exercise to burn more calories. When exercising at lower intensities and staying within the fat-burning zone, you burn fat at a slow pace, so you will need to exercise for a longer period to burn the same number of calories you would burn with cardio.
Read More: Cardiovascular Endurance Exercises To Do At Home
Now, what is the point of working out for hours when you can exercise for a shorter duration?
To get a better grip of fat-burning mode versus cardio, think about walking at a normal pace and running. With walking, your body will metabolize fat for energy, but you will burn fewer calories than you would have with running, which is a higher intensity exercise. Additionally, in the duration you take to walk 6 miles, you would probably run 9 miles increasing the number of calories you burn.
So, should you avoid intense cardio to stay in the fat-burning zone? No, you shouldn’t restrict yourself to lower intensity or moderate cardio. This is because as much as the percentage of fat you burn is higher, the overall number of calories you burn is lower compared to intense cardio.
Intense cardio exercise is better than fat-burning workouts as you get to burn more calories. Burning more calories means you lose more weight faster. Therefore, if your goal is to lose fat and weight, intense cardio is the better alternative.
Conclusion
While the fat-burning zone sounds enticing, it is often misleading. The fat-burning zone is achieved with lower to moderate cardio exercises. Much as you burn a higher fat percentage, you need to work out for prolonged periods.
With intense cardio, you get to burn more calories as your muscles demand more energy. You can try switching things up by mixing moderate and high-intensity workouts to get the most out of cardio. Remember to get adequate quality sleep, eat nutrient-dense foods, and get enough rest in between activities.
DISCLAIMER:
This article is intended for general informational purposes only and does not address individual circumstances. It is not a substitute for professional advice or help and should not be relied on to make decisions of any kind. Any action you take upon the information presented in this article is strictly at your own risk and responsibility!
SOURCES:
- Body fat percentage, obesity, and their relation to incidental risk of hypertension (2019, pubmed.gov)
- Exercise and Cardiovascular Health (2003, ahajournals.org)
- Mechanisms of nutritional and hormonal regulation of lipogenesis (2001, nih.gov)
- NIH study shows how insulin stimulates fat cells to take in glucose (2010, nih.gov)
- Nutraceutical Supplements for Weight Loss (2011, wiley.com)
- Physiological process of fat loss (2019, bnrc.springeropen.com)
