While many media outlets are promoting the new Fitbit Charge 2, fitness trackers may turn out to be not as helpful as many of us believe when it comes to helping us lose weight. Although not marketed specifically as a weight loss tool, many people use fitness trackers to monitor their daily activity primarily in an effort to lose weight.
A new study should cause us to pause in our belief that technology always helps. Sometimes, the answer is simply not that clear.
In 2014, fitness tracking devices were a $2 billion industry and they are expected to grow to over $5 billion in 2 years. That’s a lot of money being thrown at technology that is only marginally better than your current smartphone at helping you measure your daily activity levels.
Earlier this year, a class action lawsuit was filed against one of the most popular makers of these devices — Fitbit — calling their devices “highly inaccurate.” A study conducted at the California State Polytechnic University on 43 healthy adults found that Fitbit’s PurePulse heart rate monitor could miscalculate heart rates by up to 20 beats per minute — which is a pretty large margin of error for your heart rate. Another study conducted at Ball Sate University tested two wrist-worn trackers — the Fitbit Flex and Jawbone UP24, and two hip-worn trackers, the Fitbit Zip and Fitbit One — on 30 adults. That study found that the devices underestimated calorie counts by 27 to 34 percent for household work exercises and overestimated calorie counts by 16 to 40 percent for strenuous exercise.
In other words, fitness trackers today just don’t seem to be very accurate in the few things they can measure.
But none of this is news to the makers of these fitness tracking products. Because back in early 2015, Iowa State University conducted a study on 50 adults testing 7 different trackers and found that most of them were pretty inaccurate too in measuring calories expended by exercise. (That study found the BodyMedia Core was the most accurate device.)
A new study (Jakicic et al., 2016) goes one step further, however, in measuring the usefulness of fitness trackers in helping people lose weight. The study, published earlier this month in JAMA, examined the benefits of a fitness tracker in 471 younger adults (ages 18 to 35) randomized to one of two weight loss interventions. The interventions were exactly the same, except that one intervention was enhanced with the use of a fitness tracker (the BodyMedia FIT CORE), while the other did not use such a tracker. The BodyMedia FIT CORE is a device specifically marketed to help with weight management. It comes with a web-based tool as well that can help a person track their fitness and weight loss progress over time.
The hypothesis was simple — it was believed a fitness tracker should help people better monitor their activity and therefore result in greater weight loss by those who use one.
Researchers measured weight loss over a 2 year period, as most studies conducted on fitness trackers tend to be short-term (90 days or less), which benefits the device manufacturers.
Those in the fitness tracker group started the study out with an average weight of around 212 lbs and ended the study 24 months later weighing an average of 204.5 lbs. Those who were in the group that didn’t use the fitness tracker started out weighing an average of 210 lbs, and ended the study weighing an average of 197 lbs.
Yes, if your math skills are as good as mine, you’ll see the fitness tracking group lost an average of 7.5 lbs over 2 years, while those who didn’t use a fitness tracker lost an average of 13 lbs — nearly twice as much.
The researchers didn’t offer much in the way of explanation for this surprising finding, suggesting further research was needed to figure out why this occurred. This study contradicts an earlier study that examined the benefits of using a fitness tracker for weight loss (Shuger et al., 2011) over a 9 month period, finding that a fitness tracker did help more. It’s likely that the relationship between a fitness tracker and weight loss and dieting is a complex one. For instance, they may work better for a certain type of person who has certain personality, biological, psychological, or genetic characteristics.
Between the inaccuracies of these devices and this new study, one thing is clear — nobody should be pinning all of their hopes on a fitness tracker like a Fitbit to help them change their lives. Change comes from being internally motivated, not through the use of a technology gadget. While fitness trackers may help in these efforts, we should not idolize them as being anything more than a small, potentially-helpful (but perhaps not all that accurate) tool.
John M. Jakicic, PhD; Kelliann K. Davis, PhD; Renee J. Rogers, PhD1; Wendy C. King, PhD2; Marsha D. Marcus, PhD3; Diane Helsel, PhD, RD4; Amy D. Rickman, PhD, RD, LDN5; Abdus S. Wahed, PhD6; Steven H. Belle, PhD. (2016). Effect of Wearable Technology Combined With a Lifestyle Intervention on Long-term Weight Loss: The IDEA Randomized Clinical Trial. JAMA, 316.
Shuger SL, Barry VW, Sui X, et al. (2011). Electronic feedback in a diet- and physical activity-based lifestyle intervention for weight loss: a randomized controlled trial. Int J Behav Nutr Phys Act., 8, 41-49.