Are fitness trackers accurate?

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According to a study by a team of Stanford researchers most Fitbit, Fit Smart and other name brand trackers are anything but accurately giving you information.

In a paper published in the Journal of Personalized Medicine the research team reported that though the devices purport to help users track their calories — daily energy expenditures — the number is often markedly incorrect.

The least accurate, PulseOn, was off by an average of 93 percent. The most accurate devise, Fitbit Surge, was off an average of 27 percent. In a statement to NPR, PulseOn blamed the authors of the paper, saying they “may not have properly set all the user parameters on the devise.” The scientists replied that people were basing life decisions on the data provided by these devices and that the consequences of such large margins of error could be significant.

A pound of fat equals 3,500 calories. Because of inaccurate counts some would believe they had earned a tasty treat and end up sabotaging their weight-loss programs. The Stanford researchers believe that devices should keep a margin of error somewhat lower than they currently do, maybe around 10 percent.

One key issue presented by the scientists was that it is 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. The study’s participants included a diversity of ages, males and female, and they also looked at the diversity of skin tone, and then size and weight to try to represent the population generally. The devices proved most accurate for white women who were already fit. Meaning for those whom it might matter the most, who are trying to lose weight, the error is actually greater. While the energy expenditures were off drastically, most devises could accurately assess heart rate. Those readings were off by only 5 percent most of the time.

And this is not the first study to hint that these trackers aren’t accurate. A multi-year study published last September in JAMA split into two groups 500 people hoping to lose weight. One group used fitness trackers, the other did not. Those with the trackers lost about 50 percent less weight than those without.

It might behoove us to think about these studies before laying our hard earned cash on the line.

(Source: The Denver Post)

Susan Woody has been a home and garden writer for more than 20 years and is a master gardener.

By |July 13th, 2017|

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