What is the ‘Fat Burning Zone’? This is the concept that the body burns a greater amount of fat at lower intensity exercise than it does at higher intensities. It is believed that at lower intensities, the body might burn 50 percent of the calories from fat, while at higher intensities it may only burn 35 percent.
Have you ever heard of the fat burning zone or weight management zone? You can easily find this chart which is in form of a colorful graph (below) with a calibration showing a correlation between Heart rate and age on every cardio machine at the gym. Alternatively, if you are regular at the gym, I’m sure you’ve once been told by a trainer that you should train at a moderate intensity if your goal is to burn fat. What they meant is that for optimum fat burning, you must stay within a certain Heart Rate range during your workout and this is usually in reference to the fat burning zone.
The presence of this simple graph on cardio machines has led to a lot of cardio enthusiasts to think they need to reduce their intensity and work out solely in the “zone” to burn fat. This heart rate chart should however not dictate the overall effort of your workouts.
During exercise, the body relies on different forms of fuel for energy at different levels of intensity. At lower intensity activities such as walking or jogging, the body relies more on fat as fuel for energy. This is because fat takes longer to break down and it requires a lot of oxygen to be metabolized which is ideal at lower intensities.
During high intensity workouts such as High Intensity Interval Training and sprints, the body predominantly burns carbohydrates because they are easily metabolized and require less oxygen to be metabolized. This however does not mean that the body burns fat or carbs exclusively at different exercise intensities. The line between the type of fuel that the body recruit is very thin and it varies based a number of factors.
Although it’s true that a higher percentage of calories from fat are burned during low intensity workouts, following the chart as it is and trying at all costs to stick to its recommendations should not be the focus of your exercise program. Making this chart to be the driving force of your workouts is delusional because these figures are just estimates and secondly, the Heart Rates as mapped out on the chart will be different for each individual depending on their age, weight and fitness level among other variables.
The best way to put this theory to test and find out if a certain exercise protocol works long term is to either try it out and see the type of results you’ll get or to observe keenly the proponents and die-hard adherents of the protocol and analyze their results to see if it works or not. I have tried this protocol on myself and I’ve also keenly observed cardio fanatics who run almost every day and have analyzed their results, and my verdict is that the Fat Burning Zone is a myth you should discard and forget about.
You can walk on the treadmill or ride your stationary bike for all you want while sticking to the fat burning zone, if however you’re not creating a calorie deficit through a combination of different exercise modalities accompanied by good nutrition, all your efforts will be in vain. It is true you can burn a slightly higher percentage of fat when actually doing this but if there’s no calorie deficit, this will even out and you’ll remain stuck and frustrated by your lackluster results.
It is important to note that in low intensity exercise programs, the overall calorie burn will be lower than in a high intensity exercise program regardless of whether they come from fat or carbohydrates. Total calories burned are the best determinant as to whether you lose weight or not.
I’m not saying that low intensity exercise or workout routines have no place in a balanced fitness program. On the contrary, lower intensity exercise programs such as Pilates, Yoga and walking play an important role in recovery especially after a tough day of High Intensity Interval Training. They also form a good starting point for people who are overweight or obese, and are embarking on a new exercise regimen.
Shift your focus therefore from these arbitrary values on a chart and stop endlessly stressing your mind by trying to stay within the stipulated heart rate ranges for your age. The best way to gauge your intensity, which works well for a wide range of people with different fitness levels, is to use your current rate of perceived exertion (RPE) – This is your perception as to how easy or how hard your workout is. Your body will never lie to you. If the effort is easy, you’ll be comfortable, if it’s hard you’ll slightly be out of breath and if it’s difficult, you’ll be huffing and puffing feeling as though you’re about to pass out. So an excellent way of gauging intensity is to listen to how your body is responding to exercise and adjust your intensity accordingly to work at a level that is between moderate to hard.
If your goal is to lose weight or become lean, then the rate of caloric expenditure and the total number of calories expended will determine your overall results and not just a percentage of energy expenditure derived from fat. Fat or weight loss is all about burning lots of calories and cutting on the amount of calories consumed. Over the years, I’ve found that exercise programs that comprise a mixture of high intensity workouts on some days and steady state cardio on other days work very well at getting lean and trimming down and for an overall improvement in the level of fitness.
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