Most of us love to use fitness bands to calculate how much calories we’ve burnt. But according to the latest study conducted by the Guardian reports, it has been cleared that these fitness counter fails to count the calories accurately. Seven different trackers were chosen by researchers at Stanford University. They were Apple Watches, Basis Peak, Fitbit Surge, Microsoft Band, Mio Alpha 2, PulseOn and Samsung S2. These trackers were worn by group of 60 volunteers and were asked to walk or run on treadmills or use stationary bikes.
The heart rate of each volunteer was measured by a device called electrocardiograph. The calories were measured by another device that detects the amount of oxygen and carbon dioxide in the breath. The result of this study was published in the Journal of Personalized Medicine on Wednesday.
The tracker gave the counting similar to the electrocardiograph, with a slight difference of 5%. But the number counted by both the device was entirely different. The most accurate device was the Fitbit Surge with the difference of 27% between both the device. The worst-performing device, the PulseOn, was off by an astounding 93%. That means that, if the device says you burned 100 calories, it's possible you could have burned as few as 7.
"The trend we're seeing is that most of these devices are underestimating calories when people are sitting still or when they're walking at a moderate pace or cycling, and then the devices are over estimating your energy expenditure when you're running or doing some vigorous exercise," lead study author Anna Shcherbina told INSIDER. "So, the direction [of the error] depends on the intensity and the types of activity that the user is performing."
The study authors couldn't’t find out the reason behind such poor performance by all the fitness bands, but they were sure that the devices counted the calories using algorithm. They also said that using algorithms aren't accurate because it differs from individual to individual.
"Energy expenditure is variable based on someone's fitness level, height and weight," Shcherbina said in a Stanford University press release. In other words: One size does not fit all.
Researchers are next aiming to measure accuracy of these bands in daily lives and not just while they're exercising in lab.