The fat-burning zone is when you work out at about 55 to 77 percent of you max HR (maximum heart rate). This can be very misleading because limiting the intensity of your workouts won’t result in burning more fat.
How your body burns fat
Our bodies are constantly turning carbs and fat into energy for our cells to use. Depending on what we are doing the dominant energy source changes. It is also influenced by lifestyle aspects like what we have eaten recently.
The body will, in most cases, use what is immediately available in abundance. In other words, if your last meal before exercising was high in carbs then it is most likely that your body will use those carbs first to produce energy. It won’t matter how intensely you work out. The point remains that when you do a high-intensity workout your body is still going to burn fat. Along with it you will also be burning carbs in higher amounts.
Your body uses more fat than carbohydrates when you work out at 55 to 70 percent of your max HR
Mainly our bodies burn carbohydrates and fat for fuel. Our cells then convert these nutrients into adenosine triphosphate (ATP) which is a usable form of energy. Oxygen is needed for our cells to be able to turn fat into ATP. When we rest and breathe regularly, oxygen is easily available and then our bodies can metabolise fat at a slow and steady pace.
Intense exercise uses carbs for energy
When you exercise at a more intense pace your body needs to turn nutrients into ATP faster. Using carbs for this is more efficient because, unlike fat, carbs don’t always need oxygen to be able to convert it into ATP. Our bodies preserve carb stores for when oxygen is limited but we seriously need the energy.
This means that when exercise intensity increases, the amount of fuel coming from carbs does too, while the portion coming from fat becomes less. This is because when you start breathing harder to keep up with your workout, the oxygen flows to your cells decrease, which means there isn’t enough oxygen to burn fat. In this case, your body then turns carbs into energy. During the process, you are still burning both carbs and fat, but more carbs than fat.
You burn more calories at high intensity
High-intensity exercise pushes many systems in the human body to work at a harder and faster rate. The heart will have to contract faster to provide enough blood to active muscles and, in addition, our respiratory systems have to work harder and faster so that we can breathe at such an intense pace. When our muscles and organs have to work harder then they need more energy from carbs and calories to do that.
If your goal is to burn fat, then burning more calories overall will be more effective than working at a low intensity to stay in the fat-burning zone. When you work out at a higher intensity you can burn more fat in less time.
Contact Trifocus Fitness Academy
If you want to learn more about optimal fat-burning zones – as well as other must-know aspects of exercise – then you need to do our Personal Training Diploma. For more information, please follow this link.
