Do Wearables Work for Losing Weight, Getting in Shape?

Wearing a fitness tracker may not make you slimmer and fitter, but they can help

Tara Haelle

Published September 28, 2022

A finger pointing at a smartwatch on a person’s wrist

Guido Mieth/Getty Images

Fitness-tracking wearables offer benefits only if you consistently wear them and make changes based on their feedback.
Most wearables are highly accurate at counting steps but less accurate at estimating distance or calories burned.
For the best results in increasing your physical activity or losing weight, use multiple tools in addition to a fitness wearable.

You’ve slapped on a Fitbit and are geared up to get moving. But will wearing it actually lead to a slimmer, fitter, healthier you? According to researchers, that depends. A gym membership only makes you fitter if you go to the gym. Buying a salad only improves your diet if you actually eat it and skip the slice of chocolate cake after.

And fitness wearables improve your health only if you do something with the information they give you — and you keep using them. One survey, for example, found over half of those who bought a wearable device stopped using it, often in the first six months.

“Just putting on a wearable does not make you magically more physically active or thinner,” says Jennifer Gierisch, an associate professor of medicine at Duke University Medical Center. “They are a facilitator of change, and they can be very powerful for people who attend to feedback they provide.”

As associate director of the Durham VA Evidence Synthesis Program, Gierisch and colleagues reviewed the research on fitness wearables’ effectiveness in helping people lose weight or exercise more. The analysis of 14 studies revealed slight increases in physical activity and equally slight weight loss from fitness wearables — but rarely by themselves.

“We found very little support that they would be effective as a stand-alone tool to promote weight loss and increase physical activity,” Gierisch says. “These devices are more powerful when you pair them with other support.”

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Competition helps

That support could be a buddy or virtual coach who helps you set and track goals, a change in your diet or a competition at work. In fact, research published in December 2016 found that individual or team competition doubled the exercise classes college students attended. But social support without competition led to the least exercise.

“The people who are really successful at behavior change use multiple strategies, including goal setting, seeking social support and changing their environment and how they interact with their environment,” Gierisch says.

Some research suggests wearables don’t help people lose weight at all, such as one involving armband devices that measured heat from exercise instead of steps. But the participants only began wearing the device six months into a two-year program. Another study that used the same type of device within a weight-loss program found bigger weight losses among those wearing it, especially if they also received phone calls from a coach.

Device accuracy

Sales of wearable fitness devices have exploded in recent years with billions of dollars in sales worldwide. Fitbit is a major player in the market with 31 million active users in 2020. But “active user” just means someone bought, opened and activated the device. To really be active, a person has to get up and move, and psychologists have long puzzled over what motivates people to do that.

“These technologies are not a silver bullet,” says Robert Furberg, a research health informaticist at RTI International in Research Triangle Park, N.C. “We have struggled for decades to understand health behaviors, and no single technology is going to come along and alter that.”

That’s especially true if the technology isn’t accurate at everything it claims to do. In a review of 22 studies on these devices’ accuracy, Furberg and coauthors concluded they’re highly accurate for counting steps. But they get less accurate the further you get from tracking steps. In one study, a Fitbit device overestimated distance at slow speeds and underestimated it at faster speeds. Accuracy is also poor for estimating overall daily physical activity and the calories you burn. One study in August 2016 found that wearables overestimate calories burned by 16 to 40 percent while someone is walking.

Beware of the calorie count

“When it comes to an individual trending their own health behaviors and gaining insight into how they feel, how much they’re moving and how that changes over time, these devices are awesome,” Furberg says. “But don’t base how much you eat on how many calories your Fitbit says you burned because you’re probably going to gain weight.”

All of us need to move more, Furberg adds. Trying out one of these devices could offer insight into how much you’re moving — people are lousy at accurately estimating daily physical activity — and how you feel.

“For some people, getting that information is enough to empower them to drive sustainable behavior change,” Furberg says. “For others, they’re going to respond temporarily to the novelty of the device, wear it for six months and then put it in a drawer and never wear it again.”

The bottom line? Only you can make yourself take actions to improve your fitness, but wearables may be a helpful tool on that journey.

Learn more about the research in this article

• “The Impact of Wearable Motion Sensing Technologies on Physical Activity: A Systematic Review,” Department of Veterans Affairs Health Services Research & Development Service: Evidence-based Synthesis Program, September 2015. In this review, researchers analyzed 14 studies that showed wearable technology had a small positive effect on physical activity and weight loss, but these positive effects were not significant. Read the full study.

• “Support or competition? How online social networks increase physical activity: A randomized controlled trial.” Preventive Medicine Reports, December 2016. In this study, 790 students (average age of 25) were randomly split into four groups that received incentives for attending fitness classes. The students either competed against each other for individual incentives, worked as a team for team incentives, received team incentives to compete against other teams or received individual incentives. Results showed that those in the group receiving team incentives to compete against other teams had the highest average attendance per week while those in teams working for team incentives had the lowest attendance. Read the full study.

• “Effect of Wearable Technology Combined With a Lifestyle Intervention on Long-term Weight Loss: The IDEA Randomized Clinical Trial.” JAMA, September 2016. In this study, 471 adults ages 18 to 35 were randomly split into two groups. Both groups were assigned a weight loss intervention program. Six months into the program, participants in one group were given a wearable device to monitor their diet and physical activity, while the other participants had to manually monitor this data. After 24 months, researchers found that participants who were given the wearable device lost less weight than those without the device. Read the full study.

• “The Comparison of a Technology-Based System and an In-Person Behavioral Weight Loss Intervention,” Obesity, September 2012. In this study, 52 overweight adults (average age of 44) were randomly assigned a weight loss program consisting of either standard in-person behavioral weight loss classes, the standard classes plus a wearable device, or the wearable device along with the weight loss program mailed to their house and monthly phone calls. After six months, researchers found that the device along with the written program and monthly phone calls produced similar weight loss results as the standard in-person program. Read the full study.

• “Systematic review of the validity and reliability of consumer-wearable activity trackers,” International Journal of Behavioral Nutrition and Physical Activity, December 2015. In this review, researchers analyzed 22 studies that showed popular wearable activity trackers were highly accurate at estimating steps but were less accurate when measuring distance, physical activity, energy expenditure and sleep. Read the full study.

• “Validation of the Fitbit One activity monitor device during treadmill walking,” Journal of Science and Medicine in Sport, September 2014. In this study, 30 healthy adults walked or ran on a treadmill at five different speeds wearing three Fitbit One devices. Researchers counted the steps taken by the participants and compared that with the step count recorded by the devices. They also compared the distance estimated by the devices with the distance recorded by the treadmill. Results showed that the Fitbit One was highly accurate at estimating steps but was inaccurate at measuring distance. Read a summary of the study. (A fee is required to access the full study.)

• “Validity of Consumer-Based Physical Activity Monitors for Specific Activity Types,” Medicine & Science in Sports & Exercise, August 2016. In this study, the energy expenditure and step count of 30 participants were measured during sedentary, household and exercise activities. Researchers compared these values with the energy expenditure and step count estimated by several different activity trackers. The trackers were highly accurate at estimating step count but less accurate at estimating energy expenditure. Read the full study.