If the recent growth in popularity of fitness trackers is any indicator of their health benefits, you would think we’re on the verge of a wellness revolution.

But a new study—one of the largest and longest to date—suggests that although fitness trackers might help you bump up your daily steps, at least for a short time, they reportedly won’t make you much healthier in the long run.  

Most of the research on activity trackers to date has been with relatively small or short-term studies, which were often funded by the makers of the devices.

The current study, by contrast, was published in the peer-reviewed journal The Lancet Diabetes & Endocrinology, followed 800 adults for a year, and—most important—randomly assigned participants into different groups, some using the devices and some not.

Such randomized controlled clinical trials are considered the gold standard in medical research.

Specifically, the researchers, at the Duke NUS Medical School in Singapore, divided the volunteers (all of them ages 21 through 65 and mostly working office jobs) into one of these four groups:  

• One group was given a Fitbit to wear every day, plus a cash incentive of up to $22 per week if they walked at least 50,000 steps per week.
• The second group got the Fitbit and the incentive but had to donate it to a charity of their choice.
• The third group got the Fitbit but no incentive.
• The last group, which got no Fitbit and no money, served as a control.

The results were not very encouraging.

After six months, the only people to actually walk more were those who kept the cash. And even they did not lose any weight, lower their blood pressure, or improve their heart rate.

Moreover, by 12 months 90 percent of the participants gave up their Fitbit.

The researchers had hypothesized that the cash incentives would boost steps, so they were surprised by some of the results.

“I thought the Fitbit would work better than it did,” says Eric Finkelstein, Ph.D., the lead author of the study. “I also thought and hoped the charity arm would show great effects, but it did not. Lastly, I had hoped the incentives would have a greater impact on health outcomes.”

Amy McDonough, general manager of Fitbit Group Health, remains confident that the device can help people.

She points to, among other things, corporate wellness programs that encourage people to use the devices. They have helped participants lose weight and saved companies money, she says. 

"Fitbit continues to invest in the development of new devices and innovative motivational tools and social features to further enhance user engagement and help individuals achieve their health and fitness goals," McDonough adds.

Dena Bravata, M.D., a researcher who published a recent review of the research on activity trackers in the Journal of the American Medical Association, says that the new study is one of the best yet.

But she also says that it's not surprising that few people lost weight or improved their blood pressure, because most people in the study were not particularly overweight or out of shape to begin with.

Bravata suggests that studies that focus on people who are heavier or have higher blood pressure levels might show greater benefits.  

Finkelstein suspects that participants might have benefited more if they had focused not just on walking more but also on walking faster.

“If you really want to get healthy, you have to engage in brisk walking or running—something sustained,” Finkelstein says.

Increased exercise usually needs to be paired with changes in your diet to really help you lose weight and improve your overall health, he adds.  

“You shouldn’t assume that all you need to do is buy one of these devices and suddenly your health is going to improve,” Finkelstein says. “At the end of the day, diet and exercise are lifelong commitments, and technology could be part of a comprehensive intervention, but it's not sufficient."