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Fat burning heart rate zones questioned
PETE GLADDEN
Pete’s World
Published: September 25, 2023
Over the years we’ve been led to believe that there’s a specific heart rate zone that offers the highest probability of burning fat while exercising.
This so-called “fat burner zone” reflects a distinct workout intensity where the body theoretically burns more fat as a fuel source, and this zone is typically believed to lie between 50% to 72% VO2 max.
Now for those of you who regularly workout according to fat-burner zones, well, as you may or may not know, these zones rely upon workout intensity percentages that have been calculated from the oft used 220-age equation––the most common computational method to predict heart rate zones.
All that data feeds into an easy to use color coded chart where one can line age ranges up with fat-burner zones.
So keep in mind that all this computational gobbledygook boils down to some very generalized approximations.
That’s why many exercise professionals believe the fat-burner chart to be way off the mark.
They argue that the chart doesn’t consider total calorie burn, nor what happens after the workout sessions are over.
The American Council on Exercise (ACE) for instance, cautions against relying too heavily on these fat burning heart rate recommendations.
ACE maintains that people burn fat regardless of what zone they’re working out at, be it in the fat burning zone or in the cardio zone.
Thus, when you’re working out on a piece of gym equipment and utilizing its colorful fat-burning zone function, understand that this zone is not a sure fire guarantee that you’ll be burning the highest proportion of fat you’re capable of burning.
And this hotly debated issue brings us to a recent study conducted by the Mount Sinai Hospital/Mount Sinai School of Medicine.
The study, “Discrepancy between predicted and measured exercise intensity for eliciting the maximal rate of lipid oxidation,” was published in the July 15, 2023 edition of Nutrition, Metabolism and Cardiovascular Diseases (NMCD).
In it researchers postulate that, “The best heart rate for burning fat differs for each individual and often does not align with the 'fat burning zone' on commercial exercise machines.”
Instead, the study’s researchers suggest that an actual clinical exercise test (a lab procedure to measure a person's physiological response to exercise) is probably a much more beneficial tool to assist people in executing their fat loss objectives by fine tuning where exactly their fat-burning zone lies.
Now according to the Mount Sinai researchers, these theoretical fat-burning zones that are integrated as options on commercial exercise machines and advocated by fitness franchises and trainers, rely solely on age, sex and heart rate parameters, which collectively may or may not be aligned with an individual’s personalized weight loss goals.
In the study, researchers compared heart rate at FATmax (a term that’s used to characterize the exercise intensity and associated heart rate at which the body achieves its highest fat-burning rate during aerobic exercise) between clinical exercise tests and those commonly recommended fat-burning zones.
Working with 26 test subjects, researchers determined that there was insufficient agreement between the clinical tests and the fat-burning zone recommendations––with a mean difference of 23 bpm (beats per minute) between the two measures.
This suggests that those generalized fat-burning zone recommendations likely do not provide accurate guidance.
The Mount Sinai researchers are aiming to use this study as a vehicle with which to encourage more fitness professionals and health and wellness facilities to employ clinical exercise testing as the default procedure to use when prescribing personalized exercise routines geared towards fat loss.
Next up for this team of Mount Sinai researchers is a study even more focused on their clinical exercise testing thesis.
That study will examine the extent of the improvements in weight and fat loss via exercise testing and personalized exercise programs
in conjunction with any notable improvements in those critical metabolic health markers that identify health risks such as diabetes, obesity, and heart disease.
If anything, this Mount Sinai study offers some good rationale for exploring the clinical exercise testing option if your generalized fat-burning zone workouts have been ineffectual in yielding acceptable results.