Fitbit Alta

This Is Why They’re Called Fitness Trackers

A new randomized, controlled study published yesterday in JAMA found that fitness trackers added to a 24-month weight loss program did not help with weight loss. In fact, adding them actually resulted in less weight loss. People in the control arm with a standard weight loss program lost an average of 13 pounds after 24 months. People who got a fitness tracker after the first six months lost a little less than eight pounds. Bummer.

And yes, that difference was statistically significant.

Asked about the results, lead author John Jakicic explained:

These technologies are focused on physical activity, like taking steps and getting your heart rate up. People would say, “Oh, I exercised a lot today, now I can eat more.” And they might eat more than they otherwise would have.

In fairness, we should note that this study used a discontinued fitness tracker – the BodyMedia Fit Core. Its technology looks a little crude compared to the snazzy bands and smart watches popular today.

A spokesman for the market-leading Fitbit brand suggested this study was not very relevant to the company’s products, saying: “We are confident in the positive results users have seen from the Fitbit platform, including our wearable devices.”

Find Your FitNote that she did not say it would help users lose weight.

Lots of people plunk down a hundred dollars or more for a fitness tracker with the hope that it might help them lose weight. But these are, after all, fitness trackers. They work to track fitness activities.

However, working out is a lousy way to lose weight. The saying that “you can’t outrun a bad diet” captures an important insight. To their credit, the folks who market these products really do focus on fitness and not weight loss in their advertising.

Physical activity is very helpful for preventing weight gain. It is very helpful for promoting good health. It’s just not a great way to lose weight.

So don’t kid yourself that buying a fitness tracker will help you lose weight.

Click here to read the study and here here to read more from NPR.

Fitbit Alta, photograph © Fitbit, Inc.

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September 21, 2016

6 Responses to “This Is Why They’re Called Fitness Trackers”

  1. September 21, 2016 at 7:41 am, Pam Schu said:

    Thank you for commenting on this issue and, as usual, backing it up with some science. I find that my patients overwrought with concerns about not being able to exercise, due to muscular skeletal problems. They worry they will not be able to lose weight without exercise.

    • September 21, 2016 at 9:38 am, Ted said:

      Thanks, Pam!

  2. September 21, 2016 at 11:48 am, Patty Nece said:

    I’ve seen this study tweeted repeatedly with summary statements that fitness trackers don’t help you lose weight. Could it be that, once again, focussing on the number on the scale misses the most important point? The study’s results summary states: “Both groups had significant improvements in body composition, fitness, physical activity, and diet.” Isn’t this the result we should focus on?

    • September 21, 2016 at 2:47 pm, Ted said:

      Patty, your point is a good one. Fitness is an important outcome and one that is more under our personal control than weight is.

      Unfortunately, many people buy into fitness tools and regimens hoping that they will lead to weight loss. That’s a false expectation and it’s bound to lead to disappointment. Likewise, fitness trackers are for monitoring fitness activities, not weight loss.

  3. September 23, 2016 at 9:40 am, AIMEE MORENO said:

    In looking at the data, the bone mass loss between the two groups is significantly different. (table 2) Thoughts?

    • September 23, 2016 at 10:46 am, Ted said:

      Aimee, that’s a good question. It’s not clear to me that the difference is indeed significant. The authors do not call it out in any way.