When you exercise, your body uses different energy sources, primarily carbohydrates and fats. Meanwhile, the fat-burning zone represents the range of heart rates at which your body burns more fat for fuel.
South African health coverage provider Affinity Health explained that this zone typically falls within 60% to 70% of your maximum heart rate (MHR).
“Your MHR is a rough estimate of the maximum number of beats your heart can handle in one minute, and it's often calculated using the formula 220 - your age,” Affinity Health CEO Murray Hewlett says.
“For example, if you're over 30, your estimated MHR would be 190 beats per minute (220 - 30), so, in this case, your fat-burning heart rate zone would be 114 to 133 beats per minute (60% to 70% of 190).”
Hewlett also debunks the myth that the fat-burning zone is a “magic bullet”.
“It's important to understand that the fat-burning zone doesn't magically help shed unwanted kilograms without having to put in the work.”
Hewlett explains why below:
Calories still matter
Hewlett explains that while fat calories are burnt in the fat-burning zone, the overall number of calories burned might be lower than in higher-intensity workouts.
“Weight loss ultimately boils down to burning more calories than you consume.”
Total fat burn
Hewlett adds that working out at a higher intensity may lead to higher complete fat burn, even though the percentage of calories burned from fat is lower.
“It's like the difference between a gentle, steady stream eroding a rock over time and a powerful waterfall breaking it down faster.”
Time and consistency
Staying in the fat-burning zone for extended periods can be time-consuming, Hewlett concedes but insists that it is crucial to consider individual lifestyles, and how much time is devoted to exercise.
Individual variations matter
Hewlett says that it is essential to recognise that individual variations play a significant role in the effectiveness of the fat-burning zone.
This includes genetics, fitness level, and metabolism, which can influence how your body responds to exercise. “What works for one person might work differently for another,” he explained.
Finding your fat-burning zone
You might wonder, ‘Is the fat-burning zone still relevant?’ In short, Hewlett says, the answer is “yes”. This is particularly the case for beginners, those with medical conditions, or individuals looking for a low-impact workout.
Hewlett adds that while calculating your fat-burning zone, the easiest way to ensure you're exercising within your target heart rate range is to wear a heart rate monitor during workouts.
He notes that many fitness trackers and smart watches have this feature built-in.
"Some exercises can burn more calories per hour than others."
He advises that to burn the maximum calories, you should consider running. “Running is the biggest calorie-burning activity per hour.”
But if running isn't your thing, other calorie-burning activities include high-intensity interval training (HIIT) workouts, jumping rope, and swimming.
“You can perform any combination of these exercises depending on your interests and fitness level," he said.
Practical tips for effective fat burning
Hewlett advises starting with a light warm-up to elevate your heart rate gradually. This, he explains, prepares your body for more intense exercise.
“While the fat-burning zone can be effective, keep yourself open to workouts outside this range.”
Hewlett also advocates for incorporating a variety of workout intensities to keep routines exciting, and to maximise overall calorie burn.
“Remember that muscle burns more calories at rest than fat (about 50 times more), so incorporate strength training into your fitness regimen to boost your metabolism,” he said.
“Give your body adequate time to recover between workouts because over-training can lead to burnout and hinder your progress.”
Tracking your progress
To gauge the effectiveness of your workouts within the fat-burning zone and assess your weight loss journey, Hewlett recommends keeping an eye on changes in your body measurements, such as waist circumference and body fat percentage.
“Notice how you feel during and after your workouts. Increased energy levels and improved stamina can be indicators of progress.”
And while this is not the sole measure of success, tracking your weight on a scale over time can help you see trends and make necessary adjustments to your routine, Hewlett says.