Activity trackers are a fun way to keep track of steps walked, miles biked, or calories burned—but don’t expect them to automatically help you lose weight. According to a recent study in JAMA: The Journal of the American Medical Association, activity trackers may be less effective as a weight loss aid than previously believed. In fact, the study found that participants who did not use an activity tracker actually lost, on average, more weight than those who did.

In order to study the effectiveness of activity trackers, researchers at the University of Pittsburgh enlisted a group of 471 volunteers who wanted to lose weight. For six months, all volunteers followed the same diet and exercise regimen—and all lost some amount of weight. After that, volunteers were broken up into two groups: Members of one group were given wearable activity trackers to monitor their physical activity, while the other group was asked to record their daily exercise progress on a website. After 18 months, researchers weighed volunteers and observed their progress. They were surprised to find that the activity tracker group lost an average of 7.7 pounds, while those who did not use the wearable devices lost an average of 13 pounds.

Researchers are still unsure why those who wore activity trackers lost less weight than those who did not. Lead researcher John Jakicic told The New York Times he believes participants may have placed too much responsibility on the technology to help them lose weight, or became demoralized when they failed to reach their daily fitness goals. However, he says more research is needed to determine why activity trackers were ineffective, and whether they can be usefully used by some as a weight loss device.

"The findings of our study are important because effective long-term treatments are needed to address America’s obesity epidemic," Jakicic said in a statement. "We’ve found that questions remain regarding the effectiveness of wearable devices and how to best use them to modify physical activity and diet behaviors in adults seeking weight loss."

[h/t The New York Times]

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