A recent study from Stanford University suggests that fitness trackers (such as Apple Watch, Fitbit Surge and Basis Peak) are good at measuring heart rate, but not accurate at measuring calories burned. As a result, the study encourages individuals to be cautious about using these devices to determine eating habits. The study recommended that companies release data that indicated how their devices determine measurements. The accuracy of seven wrist fitness trackers were tested with 60 participants that walked, ran or cycled. The devices used in the study were the Apple Watch, Fitbit Surge, Basis Peak, Microsoft Band, PulseOn, Mio Alpha 2 and Samsung Gear S2. The study showed that six out of seven of the devices had an error rate of less than 5% when it came to measuring heart rate.
When it came to keeping track of energy used during exercise, every device had an error rate of about 20%.
Dr Euan Ashley, co-author of the study from the department of cardiovascular medicine at Stanford University, stated "If you go to the gym, and you think you've lost 400 calories, then you might feel you've got 400 calories to play with. That could be an issue if people were basing their diet on what they thought they had burnt off." There is also a very wide difference in calories burnt between one person and another, and fitness trackers do not seem to accurately calculate calories burned for every individual.
Fitness trackers may have a positive effect on activity levels, so complete accuracy may not be necessary if the devices are encouraging more exercise overall. However, other trials have recently suggested that wearing fitness trackers doesn't always result in a positive outcome or improved weight loss.
Full article here: http://www.bbc.com/news/health-40030457