The 470 people in the study were put on a low-calorie diet and asked to exercise more. They all started losing weight. Six months in, half the group started self-reporting their diet and exercise. The other half were given fitness trackers to monitor their activity.
After two years, both groups were equally active. But the people with the fitness trackers lost less weight.
Wait. What? We asked John Jakicic, a researcher of health and physical activity at the University of Pittsburgh and the lead author on the study, why this could be.
“These technologies are focused on physical activity, like taking steps and getting your heart rate up,” says Jakicic. “People would say, ‘Oh, I exercised a lot today, now I can eat more.’ And they might eat more than they otherwise would have.”
It’s also possible, he says, that meeting daily fitness goals and step counts might motivate one person, but missing those same goals could discourage another.
The device in the study, which was published Tuesday in JAMA, the journal of the American Medical Association, wasn’t a wrist-tracker like the Fitbits, Jawbones, Apple watches and Nike bands many use now. This device was worn around the upper arm. Instead of using heart rate to estimate activity like some devices do, it measured the heat generated by exercise.
Still, he says, the results from this study are relevant to the devices of today.
Overall the participants without fitness trackers lost 13 pounds, while the tech-enhanced group lost 7.7 pounds. They ranged in age from 18 to 35 years, and had BMIs from 25 to 39. The study hopes to see if helping young adults lose weight early on can head off more weight gain in middle age.
We reached out to Fitbit to see what they thought of the study.
“We are confident in the positive results …