It seems like a no-brainer: give all of your workers—more than 300,000 of them—a trendy fitness tracking device, and then sit back as they shed thousands of pounds, improve their health significantly and help control insurance costs.
That's apparently the theory behind Target's new plan to give Fitbit activity trackers to its American workforce.
But the mega-retailer's big idea might end up actually producing only small concrete gains—if that.
Target's move to improve employee well-being, while laudable, faces several potential hurdles, including getting significant numbers of workers to take up the company's offer of free or subsidized Fitbits, and then getting those Fitbit adopters to become more active in a way that will actually improve their health.
Another big question: how many of those Fitbit users will actually continue to make use of the device once the novelty of tracking the daily number of steps they take inevitably wears off?
"I do think there's often a misperception that simply giving somebody a wearable device is going to make them more active, more healthy," said Dr. Mitesh Patel, a University of Pennsylvania associate professor who has researched activity trackers.
Patel noted that people who are inclined to use devices such as Fitbits tend to be the most motivated to get, or remain healthy, and not the people with health conditions who could be most helped by increased activity.
"Wearable devices seem to appeal to groups that might need them the least," Patel and his co-authors wrote in a paper published online by the JAMA Network earlier this year.
Because Target's offer is not mandatory, some—or many—workers may not accept the Fitbits.
And there is no guarantee that the workers who do accept the Fitbits will keep using them. One study, by Endeavour Partners, found that among more than 6,200 U.S. adults who had bought a wearable device, more than half stopped using it, and one-third of respondents said they ceased using the trackers before six months had elapsed.
Earlier this year, The Associated Press reported, the health-care investment fund Rock Health said that Fitbit's own financial filings suggest that out of almost 20 million registered users of the device, just half were still actively using it.
Patel told CNBC that one hurdle to widespread continued use among workers is presented by the devices themselves.
"They need to be charged up, synched up" to share their data about a user's activity level, he said. "Those little extra steps really end up to be high hurdles."
Patel said companies like Target can improve the level of adoption and continued use of activity trackers by designing programs that encourage both, and not just by assuming that people will utilize the devices to their advantage.
CNBC reached out to both Target and Fitbit for comment, but had not yet received a response.
However, Target has said it will design programs around the use of the Fitbits, the first of which will be a monthlong competition in which teams of Fitbit users will track their activity levels, with the winners naming a charity that will receive a $1 million donation from the retailer.
"The design of this competition is what's most important," Patel said, adding that in other cases of programs to promote Fitbit use the design often isn't given much thought.
One might think that competition with one's self—the competition of getting below your current weight—would be enough for people to use Fitbit. But hitting the goals of increased steps don't necessarily translate into weight loss.
Today.com, in an article last year, cited the cases of several Fitbit users who had actually gained weight even though their devices indicated that their step counts were outpacing their calorie intake.
Korie Mulholland, a private SAT tutor from Chicago, said that even as she was walking 10 to 15 miles daily at a stand-up desk, her weight increased despite her following the Fitbit's calorie guidelines.
"It was clearly telling me to eat too much for my specific metabolism and no matter what I did, it just wasn't working right," Mulholland said. "I used it for six months, until I gave up."
Jessica Reed, a poet and blogger, also has written about gaining weight while using Fitbit despite eating fewer calories than the device indicated she was burning.
"In the past three weeks, I've burned 6,300 more calories than I've consumed. I know this because I have an app on my phone (Lose It!) that keeps track of the calories I eat," Reed wrote in an updated blog post after Today.com cited her experience.
"This app is integrated with my Fitbit Flex wristband, which keeps track of the calories I burn. The math says that I should lose a pound for every 3,500 calories burned. The bathroom scale, however, says I have gained two pounds," Reed wrote.