Study finds popular fitness trackers may overestimate calorie burning

Though fitness trackers may be great for motivation or keeping an eye on one's general activity levels, they may not be terribly accurate when it comes to estimating the amount of calories the user has burned. The research, which comes out of the UK's Aberystwyth University, found that three popular fitness trackers tended to overestimate the amount of calories the users burned, in one case exceeding the actual amount by more than 50-percent.

The researchers studied the accuracy of the Leftsfit, Letscom HR, and Fitbit Charge 2 for a BBC Wales program — their work involved a total of 12 participants, six who were male and six who were female.

During the testing, these participants were told to spend 10 minutes walking on a treadmill at around 2.5mph, then jogging at around 6.6mph. The researchers used indirect calorimetry to monitor how much oxygen the participants used during the exercise, comparing it with data gathered by the fitness trackers.

Based on their data, the researchers found that while walking, the Letscom HR had the most accurate calories burned estimate, overestimating the number by only 2.6-percent. In comparison, the Letscom HR overestimated by 15.7-percent and the Fitbit by 53.5-percent.

However, the numbers flipped when comparing the jogging data — Fitbit had the closest estimate, under-predicting by 4.3-percent, while the Letscom HR was 33.4-percent under and the Letsfit was 40.1-percent under. Across the board, the researchers found that all three fitness tracking models had better prediction with female participants than male participants.

Of course, the potential for inaccuracy doesn't mean these trackers aren't useful. Individuals can use tracking devices to monitor how long they've been active in a day, as well as seeing an overall activity trend over time. Even if a band is inaccurate to a degree, the figures it offers over time will remain consistent, providing a general overview...though one that may not always feature a high degree of precision.