A new says fitness trackers are not so in measuring the amount of calories our body burns while , and that this may lead people to make decisions about their diet. The study is from Stanford University in the USA. Researchers evaluated the of five popular trackers. These included the Apple Watch, Microsoft Band, Fitbit Surge and Samsung Gear S2. The researchers observed 60 as they walked, ran and cycled while wearing the . Researchers found that none of the devices had an error below 20 per cent. Dr Euan Ashley, co- of the study, said: "People need to know that on energy expenditure, [the trackers] give rough ."
The Stanford scientists said of fitness trackers should be cautious about using the devices to judge what they eat. Dr Ashley said: "If you go to the , and you think you've lost 400 calories, then you might feel you've got 400 to play with." This could be a for those who base what they eat on how many calories their fitness tracker said they burned. One CEO of a fitness tracker company suggested the may not have adjusted the user properly. The CEO told the USA Today newspaper that the study could have reported incorrect , saying: "We think the excess error reported in expenditure is not representative in this study, due to this methodological ."