Frustrated by your FitBit? You’re not the only one.

A new study from the University of Pittsburgh found that people who used a fitness tracker while dieting lost less weight than people who didn’t use one.

Researchers studied 470 overweight or obese people between the ages of 18 and 35 – all participants were put on a low-calorie diet and increased their activity, and after six months of dieting, half of the group was given BodyMedia Fit Core armbands to track their results.

Of the 350 people (75 percent) who finished the two-year study, those who dieted without the tracker lost an average of 13 pounds, while the group with the armbands lost only 7.7 pounds on average. Why?

“They are relying on the device too much,” explains lead author John Jakicic, PHD. “[The trackers] may give people a false sense of security, [so] they don’t pay attention to some of the key behaviors that they need to pay attention to.”

Both groups did see overall improvements in body composition, amount of physical activity and diet, so the authors will be studying the matter further. Read the full results of the study here.