In an effort to shed unwanted body fat, many dieters and exercisers embrace the idea of performing slow, steady-state aerobic exercises such as a light jog on the treadmill or a slow hike up a stairclimber. Until recently, this long duration, slow-paced type of exercise has been hailed the ideal way to lose weight as exercisers work within their "fat-burning zone." However, as of late, the fitness industry is reeling around the idea of participating in "HIIT" training - or 'High Intensity Interval Training' - for maximum fat-burning results.
What is the fat-burning zone and HIIT, and which one is the best method of obtaining maximum fat-burning results? How will these method of exercising affect your own weight loss strategy? Before you decide which method of exercising is right for you, it's important to understand what the fat-burning zone and HIIT are.
What is the Fat Burning Zone?
Long duration, slow-paced exercises like jogging on the treadmill, steadily climbing stairs, or going for a brisk walk are all examples of low intensity exercises where a person works within their "fat-burning zone." It is within this level of intensity that the higher percentage of fat is being burned. At this pace, the heart rate is pumping at no more than approximately 60% - 65% of the maximum heart rate, and the body is relying on a higher percentage of fat as its source of fuel for this low-intensity level of activity.
In essence, the lower the intensity of a particular exercise or activity, the higher the percentage of fats are being utilized by the body for fuel - as opposed to carbohydrates or proteins. In contrast, the higher the intensity of the activity, the higher percentage of carbohydrates are being relied upon by the body as its source of energy.
What is HIIT?
Short for 'High Intensity Interval Training,' this type of specialized training involves short bursts or intervals of maximum intensity activity, followed by longer intervals of low exercise or active rest. It is within this high-intensity level of activity - approximately 85% of the maximum heart rate - that the body relies mainly on carbohydrates as the primary source of fuel. Since HIIT involves briefly pushing your body beyond the upper end of your aerobic zone and into the anaerobic zone, your body will expend a great deal of energy to perform such intense exercise.
How Do You Reach the Fat-Burning Zone and HIIT?
The fat-burning zone is achieved when you work within a 55% to 65% maximum heart rate range for at least 30 to 60 minutes. Regardless of the type of exercise you are performing, staying within this low-intensity range will have you reaching your fat-burning zone, which is said to be the range where the highest percentage of fat is used as the body's primary source of energy used to perform the activity.
To reach the HIIT zone, your goal is to work within a sub-maximal heart rate range of anywhere between 80% to 85% of your maximal heart rate for short durations of approximately 10 to 30 seconds, followed by short periods of active rest or very low intensity work before repeating the cycle. These workouts should last no more than 20 to 30 minutes. It has been shown that a higher ratio of carbohydrates are used as the body's main source of fuel to perform such strenuous exercise.
What Happens If You Train at an Intensity That is Too Low or Too High?
Exercises need to be intense enough that they challenge your body sufficiently. If you are working out below a 55% maximal heart rate range, you are not stimulating your body enough to warrant any results or changes in your fitness level. In addition, you won't burn enough fat or calories to achieve your weight loss goals.
In contrast, working out above the 85% maximal heart rate range for long periods of time can put you at risk for over-exertion, fatigue, risk of injury, chest pain, dizziness, and an irregular pulse. Your ability to work out on a regular basis may decrease as your body may find it difficult to keep up with such a strenuous routine, putting your weight loss and fat burning goals in jeopardy.
What is The Best Method of Burning Fat and Losing Weight?
Recent studies have suggested that performing 3 days per week of HIIT at 20 to 30 minutes per session may have much higher fat-burning properties than performing longer duration exercises within the fat burning zone. Although it is true that the percentage of fat burned is higher when working out within the fat burning zone as opposed to performing HIIT routines, the actual total number of calories burned is much higher with HIIT.
This is where the misunderstanding comes in - focusing too much on the proportion of fat being burned takes away from the impact that high intensity activity has on fat reduction, regardless of percentages. For example, a 130 pound woman will burn approximately 146 calories during a 30-minute low intensity exercise within the fat burning zone, with 50% of those calories burned coming from fat. This same 130 pound woman will expend approximately 206 calories in 30 minutes of higher intensity exercise, with 39.85% of those calories coming from fat.
The actual number of fat calories burned in this scenario during this woman's low intensity workout is 73 in comparison to 82 fat calories burned during the HIIT style routine. Although the ratio of fat burned is higher with the lower intensity exercise, the actual total number of fat calories burned is higher with HIIT style workouts.
The Bottom Line
There really is no 'myth' surrounding the fat-burning zone, since participating in such activity will inevitably burn fat and calories. However, HIIT provides a much more time-efficient and effective way to burn fat and also helps to highly engage large muscle groups through such activity. At the end of the day, it may come down to personal preference as well as your overall health and fitness level. What works for you is the the right way.
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