Fitness trackers have become ubiquitous over the past few years. Whether not-so-cleverly disguised as a watch or a funky bracelet, almost everyone seems to be tracking her heart rate, steps, and sleep quality. This has even affected well known brands like Weight Watchers.One would hope that the results would be accurate, but that is not the case! According to a recent study at Australia's University of Queensland, the most commonly used fitness trackers greatly underestimate energy expenditure, which can be a health hazard instead of a health boon.

Fitness Trackers don't track well

Somehow, one would would hope that a fitness tracker would minimally track things well, but that is not the case. In the Australian study, researchers looked at fitness trackers from Apple, Mio, Samsung, and Fitbit. They were all off 9% - 43% in energy expenditure, with heart rate being somewhat more accurate.This can be a problem for anyone who must carefully monitor exercise intensity. If you follow the tracker data, you can end up pushing too hard, or not hard enough.What they do count well are steps, but so does a very inexpensive pedometer and, in fact, most smartphones.

In fact, a recent study a University of Pennsylvania showed that smartphones record steps more accurately, with less variation, than fitness trackers.

Fitness Trackers leak data

In the age of identity theft, most of us are trying to limit the amount of personal data we leave in the world. But our fitness trackers are giving out data all the time. Like to walk in a shopping mall? Your tracker follows that, and so can criminals who hack that data.A new study from the University of Toronto hows that some fitness tracking companies are using users' data in questionable ways.

Some trackers store information about where and when you move, which can give robbers information on when you are not home. Others send your numbers and information as unencrypted data, where they can be viewed by a third party.

At the end of the day, you don't need a device to tell you if you had an intense workout, a good night's sleep, or weight loss. Pay attention to how you feel, and you will know how your body is doing.

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