Counting calories is an effective weight-loss method that has been tried and tested. But a new study suggests that a fitness tracker could undo, instead of help, these efforts.
Fitness trackers have seen a surge in popularity in recent years. Fitbit, for example, the leading brand in such devices, has sold at least 30 million of them, The Washington Post reports. According to the company website, Fitbits “track steps, distance, calories burned, floors climbed, active minutes & hourly activity.” Similar devices from big-name gadget brands like Apple, Samsung and Microsoft all carry the same advertising tune.
But a research team from Stanford have debunked these claims after testing fitness trackers. According to their findings, most calorie count readings these devices give off are inaccurate.
According to the study, the least accurate fitness tracker is PulseOn, which proved to be off by 93%. The most correct count was with Fitbit Surge, but even it was off by 27%.
Euan Ashley, a professor of cardiovascular medicine at Stanford, and co-author on the study, said that the consequences of these margins of error are huge.
People are basing life decisions on the data provided by these devices.
For example, a user who checks his or her tracking device might find that they burned 1,000 calories for the day, when in reality, it was less than 700. They might indulge in extra food or drink, which can then add up to calories they’re not even aware of.
While a margin of error in such devices isn’t unusual, the researchers say that the discrepancy should not be this big. Anna Shcherbina, a Stanford graduate student, and co-author on the study, said, “For a lay user, in a non-medical setting, we want to keep that error under 10 percent.”
The study participants were composed of people with a “diversity of ages, male and female, and then also we looked at diversity of skin tone, and then size and weight to try and represent the population generally,” Ashley said, to allow for the differences in body types.
On the bright side, the fitness trackers performed well in measuring heart rates. Ashley said, “The heart rate measurements performed far better than expected.”
The study was published in the Journal of Personalized Medicine.
