Enlarge / Ruth Rohs, who works for IMA Financial Group, wears a Fitbit to track his steps. Her company is trying to promote healthy behavior on the job. (credit: Getty | RJ Sangosti)

According to a two-year study, wearable fitness trackers designed to coax users into busting moves and burning calories throughout their daily lives didn’t help anyone lose weight. In fact, overweight dieters using the arm-mounted gizmos actually gained more weight on average than those using old-fashioned, tech-less dieting schemes. The study, published Tuesday in JAMA, contradicts earlier studies that found the trackers can boost weight loss. But those earlier trials tended to be smaller and shorter.

The new data, the authors say, suggests that tossing technology at big problems, like fitness, diet, willpower, and motivation, isn’t straightforward and requires more nuanced, long-term studies. “I think we have to be a little bit cautious about simply thinking that what we can do is just add technology to these already effective interventions and expect better results,” lead study researcher John Jakicic, of the University of Pittsburgh, said in an interview with JAMA.