Though commercial exercise machines often tout a ‘fat-burning zone’ setting in their devices that can be set based on the user’s age, gender, heart rate or other physical measures, new studies show that the best heart rate for burning fat does not align with the markers on these machines, and differs widely among people within the same age or gender group.
Researchers at the Mount Sinai Hospital in the United States say that, rather than rely on settings provided by these machines, people looking to lose weight or fat should follow the recommendations of a clinical exercise test — a diagnostic procedure to measure a person’s physiological response to exercise. They note that the clinical test may be a more useful tool to help individuals achieve intended fat loss goals.
The study, which used a machine learning-based modeling approach, found that people with a goal of weight or fat loss may be better served by exercising at the intensity which allows for the maximal rate of fat burning, found by undergoing a clinical exercise test. The researchers added that the fat-burning zone mark on exercise machines has not been scientifically validated, and could leave individuals exercising at intensities that are not aligned with their personalized weight loss goals, and cause people to exercise at intensities that are not aligned with their personalized weight loss goals.
The term FATmax is sometimes used to represent the exercise intensity and associated heart rate at which the body reaches its highest fat-burning rate during aerobic exercise. At this point, fat is a significant fuel source and therefore this intensity may be of interest to those seeking to optimize fat loss during workouts.
As part of the study, the researchers compared heart rate at FATmax, as measured during a clinical exercise test, to predicted heart rate at percentages of maximal effort within the typically recommended ‘fat-burning zone’. In a sample of 26 individuals, the researchers found that there was poor agreement between measured and predicted heart rate, with a mean difference of 23 beats per minute between the two measures. This suggests that general recommendations for a ‘fat-burning zone’ may not provide accurate guidance.
Next, the researchers plan to study whether individuals who receive a more personalized exercise prescription demonstrate more weight and fat loss, as well as improvement of metabolic health markers that identify health risks like type 2 diabetes, obesity, and heart disease.
“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 the research team in their published report.