Know Your Pace: Fat Burn Rate Varies Between Individuals, Study Reveals
19:12 13.08.2023 (Updated: 19:20 13.08.2023)
© AP Photo / John Locher
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In recent years, the concept of FatMax, a zone of optimal exercise intensity for fat burning, has gained wide acceptance. It has been suggested that the FatMax zone is around 70% of maximum heart rate for trained athletes, and slightly lower for beginners. However, recent findings show that this issue is not as simple as it seems.
The optimal heart rate for burning fat varies widely among individuals and often does not correspond to the "fat-burning zone" indicated on commercial exercise equipment, a new study published in the journal Nutrition, Metabolism and Cardiovascular Disease has revealed.
Researchers from the Icahn School of Medicine at Mount Sinai, New York City, suggested that a more personalized approach to exercise is needed.
The scientists recommended that those who want to achieve their fat loss goals should undergo clinical exercise testing, a diagnostic procedure that measures an individual's response to exercise, stating that this would be a more useful tool for achieving visible results.
"Our results indicate that estimated 'fat-burning' heart rate zones are inappropriate for prescribing exercise [...] and we recommend direct individual exercise lipid oxidation measurements to elicit these values," read the study.
The term FatMax is used to refer to the training intensity and associated heart rate at which the body reaches its maximum fat-burning rate during aerobic exercise. According to lead author Hannah Kittrell, since fat is an important fuel source at this point, this intensity may be of interest to those seeking to optimize weight or fat loss during training.
"Most commercial exercise machines offer a 'fat-burning zone' option, depending upon age, sex, and heart rate," said Kittrell, a PhD candidate at Icahn Mount Sinai in the Augmented Intelligence in Medicine and Science laboratory. "However, the typically recommended fat-burning zone has not been validated, thus individuals may be exercising at intensities that are not aligned with their personalized weight loss goals."
As part of the study, which used a machine learning-based modeling approach, researchers compared the FatMax heart rate measured during clinical exercise testing with the predicted heart rate as a percentage of maximum effort within the commonly recommended "fat-burning zone".
The scientists found weak correlations between measured and predicted heart rates, with an average difference of 23 beats per minute. This means that generally accepted "fat burning zone" recommendations may not be accurate.
The researchers confirmed that they would continue to study this issue to see if people who receive more personalized exercise prescriptions experience greater weight and fat loss, as well as show improvements in metabolic health markers.
"We hope that this work will inspire more individuals and trainers to utilize clinical exercise testing to prescribe personalized exercise routines tailored to fat loss. It also emphasizes the role that data-driven approaches can have toward precision exercise," said senior author Girish Nadkarni
