Some say fitness trackers don’t work. This physician disagrees.


I am devoted to my fitness tracker, having used it for several years to remind me to be active, monitor my diet and improve my sleep. Now The New York Times tells me it doesn’t make a difference, at least when it comes to the weight loss part of the program. And I might agree if only the evidence they relied on told the whole story. In my opinion, it did not.

Unfortunately, some of the science on which the Times reporter based his comments had a possible flaw that may influence the conclusion that fitness trackers not only don’t encourage weight loss but improbably may lead to less weight loss when using the device.

That, my friends, would be a real bummer. However, if you had evaluated that research closely, you may have been aware of the problem. From where I sit, I don’t think many folks have made that effort. And I remain unconvinced that the research supports the conclusion that fitness trackers — when used in typical real-life situations — don’t make a difference in keeping us engaged in our health, including as an adjunct in weight loss programs.

Body weight is an important risk factor for many cancers. Eating a healthy diet and keeping your weight in line reduces your risk of cancer. Anything that would help many of us achieve those goals —
such as becoming or remaining more active — is useful. So concluding that fitness trackers don’t help us along our journey of health is important, especially if it is based on sound scientific evidence.

The study in question was published about five months ago in the Journal of the American Medical Association. The authors concluded that the addition of a fitness tracker for one-half of the participants in an intensive weight loss program did not improve weight loss compared to the other participants who received all of the same interventions with the exception of the fitness tracker. In fact, the group with the fitness trackers lost less weight. The exact reasons for that were not certain, and the authors noted that more research was indicated to answer that question.

470 participants were randomly assigned to “intervention” and “control” groups. The interventions for both the study and control groups included a calorie restricted diet, very close monitoring including regular “check-ins” with staff, telephone counseling, text messages and web support. The additional intervention — and the focus of this research — was the addition of the fitness tracker, provided to one-half of the participants after everyone had been on the program for six months.

After two years, the intervention group lost an average of 7.7 pounds while the control group — which did not use the fitness trackers — lost an average of 13 pounds. That’s over five pounds more, without using the fitness tracker. Not exactly the expected result, but the facts are the facts. The fitness tracker not only didn’t promote weight loss but for some unknown reason, it actually had the opposite effect.

This study contained an interesting statement to the effect that over time, all of the participants in both the intervention and control groups were prescribed “moderate to vigorous physical activity,” increasing from 100 minutes a day to 300 minutes a week over four-week intervals.

300 minutes of moderate to vigorous exercise a week!!!! Think about that: for five days a week, that’s an hour a day. Exercise every day of the week, and you will spend over 40 minutes a day working your butt off.

I don’t know about you, but I try to be reasonably active — and for people like me, that just isn’t part of the program. Maybe if you are 20 or 30, but not commonly when you are in your 50s, 60s or 70s. And that activity program applied to both groups of the study: those who wore the tracker, and those who didn’t.

My hunch is that if you didn’t wear a tracker and exercised vigorously for 60 minutes a day five days a week you were still going to lose weight. You are MOTIVATED, especially if you do it for two years. Would you expect a fitness tracker to make a difference under those requirements? Uh, may I suggest probably not? Wearing that tracker simply isn’t going to get me to take those 10,000 additional steps. Heck, I’d be happy if I could hobble back to the locker room or my shower at home! (Definitions of moderate and vigorous physical activity and the American Cancer Society recommendations for physical exercise can be found here.)

So for me, the jury is still out whether trackers make a difference in weight loss, although I must concede the published evidence is not on my side.

I still believe that being engaged in your health can help us become a healthier nation. It has for me, and I know it has for others. How that plays out in the general population and how we incorporate that information into our everyday health journey is still a work in progress. It may work for some committed folks, may not work for others, and may encourage that large middle mass (pardon the pun) to do just a bit more than they otherwise would.

The lesson? Headlines are “grabbing,” details are boring, but it’s the details that count. Sometimes one has to go beyond the headline, read the information critically, and then make a decision whether the evidence is the evidence you need to make the best decision — whether it is for the health of the public or you as an individual.

For me? The fitness tracker stays in place. Now all I have to do is lose the weight.

J. Leonard Lichtenfeld is deputy chief medical officer, American Cancer Society. He blogs at Dr. Len’s Cancer Blog.

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