Why You Shouldn’t Always Trust Your Fitness Tracker

This news could change the way you exercise. - by Lauren Williamson

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Seeing how many calories you’re burning off can be a major motivator when it comes to slogging it out in the gym, but a recent study has found that many popular fitness trackers could be way off with their calculations.

Researchers from Stanford University tested seven different devices – Apple Watch, Basis Peak, Fitbit Surge, Microsoft Band, Mio Alpha 2, PulseOn, and the Samsung Gear S2 – on 31 women and 29 men. The experiment compared the energy expenditure determined by the trackers in comparison to ‘gold-standard clinical measures’.

They found that the most accurate device was the Fitbit Surge, but it was still off by an average of 27.4 per cent. The PulseOn's average error was a whopping 92.6 per cent.

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Co-author of the study, Dr. Euan Ashley, told the Guardian that each tracker uses its own proprietary algorithm to figure out how many calories are being burned.

"My take on this is that it's very hard to train an algorithm that would be accurate across a wide variety of people because energy expenditure is variable based on someone's fitness level, height and weight, etc,” Ashley told the publication.

NPR reports that Fitbit and PulseOn remain confident with the performance of their technology. In a statement PulseOn suggested that the authors may not have set all the user parameters on the device correctly leading to the high error average.

So while it’s great to keep an eye on your daily steps and strive to slay those calories, Ashley says you probably shouldn’t be basing your decision to have a doughnut on a device.