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Wearable fitness trackers may not help with weight loss, study finds

This study, like all studies, has several limitations. The most important one, says lead author John Jakicic, is that the fitness device used in the study is now outdated. Newer devices are worn on the wrist rather than on the arm.

Adding a fitness tracker to a weight-loss regime doesn’t help people lose any additional weight or keep it off over the long run, according to a recent study published in the Journal of the American Medical Association (JAMA).

In fact, “wearing the technology actually resulted in less weight loss than not wearing the technology,” says John Jakicic, the study’s lead author and chair of the University of Pittsburgh’s Department of Health and Physical Activity, in a video released with the study.

This is discouraging news. Many people in the medical and public health fields have been hoping that new technologies like fitness trackers — which provide daily information on how much we are moving and how many calories we are using — might help turn around the current global obesity epidemic. Here in the United States, an estimated 70 percent of adults are either overweight or obese, factors that put them at increased risk for numerous health conditions, including heart disease, stroke, type 2 diabetes, certain cancers, osteoarthritis and sleep apnea.

Identifying effective strategies that can help people shed excess pounds — and, more important, keep them off — has been a challenge for both overweight individuals and health officials alike. Previous research had suggested that fitness trackers help people achieve modest, short-term improvements in weight loss. The current study set out to determine if such technologies could also help improve health behaviors over the long term.

Study details

For the study, Jakicic and his colleagues conducted a randomized controlled clinical trial, considered the “gold standard” of studies. They recruited 471 overweight or obese young adults, aged 18 to 35. All had a body mass index (BMI) between 25 and 40.

The participants were put on the same behavioral weight-loss plan, which focused on a low-calorie diet and regular exercise. They were told to track their food choices and physical activity in diaries, which were shared with weight-loss counselors for feedback. Participants were also invited to attend regular group counseling sessions.

After six months, the participants were randomized to one of two groups. About half were told to continue self-monitoring their food intake and exercise by putting the data daily on a website designed especially for the study. In addition, they received telephone counseling and regular text messages to encourage compliance with the weight-loss program.

The rest of the participants were told to do the same. But they were also given a wearable device to help them monitor their physical activity.

Key findings

All the participants had shed pounds after the first six months. But an analysis of the data after two years turned up a surprise: The people in the self-monitoring “arm” of the study had sustained a greater weight loss, on average, than those using the fitness trackers.

In fact, they had dropped almost twice as many pounds. The average weight loss in the self-monitoring group after two years was 13 pounds, compared to 7.7 pounds in the group with fitness trackers.

The amount of body fat lost was also significantly different. People in the self-monitoring group had lost an average of 3.5 percent of their body fat over the two years compared to an average of 2.4 percent for the fitness-device wearers.

“Devices that monitor and provide feedback on physical activity may not offer an advantage over standard behavioural weight loss approaches,” Jakicic and his colleagues write (with British spellings).


This study, like all studies, has several limitations. The most important one, says Jakicic, is that the fitness device used in the study — Body Media’s FIT Core — is now outdated. Newer devices, he points out, are worn on the wrist rather than on the arm.  Also, this study involved only young adults, and most (77 percent) were women. The findings, therefore, may not be representative of a broader population.

“At the end of the day, …  I think we have to be a little bit cautious about simply thinking that we can just add technologies to these already effective [weight-loss] interventions and expect better results,” says Jakicic. 

That’s not to say, he adds, that certain people won’t find fitness trackers  — particularly the newer models — helpful.

“For some individuals, these might be very effective,” says Jakicic. “For other individuals, they may not be appealing and be less effective. I think we have to tease this out a bit and try to understand when and where and how we use these technologies before we just simply implement them broadly across the population.”

FMI: The study can be found on the JAMA website, where it can be read for free in full if you sign up for a personal account. The study was funded by a grant from the National Institutes of Health. Jakicic and two of his co-authors have received honorariums and/or grant money in the past from Weight Watchers International.

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