Last year I bought a Lumo Lift, a device that tracks calories and buzzes whenever its wearer slouches. I wore it for about two weeks, wrote an article about it, and put it in a drawer. There it has sat, forlorn and uncharged, ever since.

My experience is apparently not unusual. The authors of a new editorial in the Journal of the American Medical Association point out that fitness trackers, like the FitBit and Jawbone, only work if they're worn consistently, in the right way, and by people who actually need to become more healthy. And despite the gadgets' proliferation in recent years, each one of those factors is kind of a long shot.

The authors, Mitesh Patel, David Asch, and Kevin Volpp of the University of Pennsylvania, point to a survey showing that only about one or two percent of Americans use wearables. (Depending on the definition of "wearable," other surveys have found a much higher number—about 20 percent.)

Among those who buy them, about half are younger than 35 and nearly a third earn more than $100,000 a year, the JAMA authors write. In other words, they're not likely to be the people who need the most help to lose weight.

On top of that, they note, more than half of people who buy fitness trackers stop using them. A third do so within six months. And for the rest, consistency is a struggle: An earlier report from PricewaterhouseCoopers found that among people who own any kind of wearable device, only 10 percent wear it every day and 7 percent wear it a few times a week. The rest are fair-weather FitBitters, donning their devices a few times a month or less.

The PwC report, too, found that the young, wealthy, and educated are more likely to own the devices.

So does this mean that fitness trackers—an industry that's expected to grow to $50 billion by 2018—aren't very good at actually increasing fitness?

The authors of the JAMA article don't go quite that far. "If wearable devices are to be part of the solution, they either need to create enduring new habits, turning external motivations into internal ones (which is difficult), or they need to sustain their external motivation (which is also difficult)," they write.

Wearable devices tend to better hack our lazy, hedonic-treadmill brains if they are integrated into smartphones, the devices we rarely leave home without, or send out visual or auditory reminders.

One option might be for employers to deploy fitness trackers in workplace-wide fitness competitions ... but these types of contests, Patel and his colleagues note, tend to engage the already-active fitness buffs of the office, and not the people who just need to get off the couch.

Instead, the authors recommend something along these lines:

Individuals form teams that provide peer support and promote a sense of accountability to use the device and stay engaged in the new behavior—perhaps aiming for everyone to achieve a minimum amount of activity (eg, 7000 steps per day), rather than simply rewarding the power walkers. For example, teams might be selected at random in a regular drawing, but winning teams would only be eligible to collect their reward if the team had achieved its targeted behavior on the previous day.

Of course, whether people would stay in a job where they were rewarded based on the jogging abilities of their co-workers is another question.