fitness trackers

Study: Activity trackers not effective tools for weight loss

Technology is amazing. I use it every day to find the latest health and fitness news. I use it to coach my clients, interacting with them via Precision Nutrition's ProCoach platform and viewing their customized workout programs on

Some of my favorite stories I've reported during the past decade as an NBA journalist involved teams' growing reliance on technology to improve player performance and prevent injury -- such as this piece on the Golden State Warriors' use of wearable technology and this one on the importance of sleep.

Wearable technology is omnipresent in the fitness industry. From Garmins to Fitbits to Apple watches and Jawbones, it's become a cool trend for everyone to know exactly how many calories they're burning each day.

The only problem is, activity trackers may not help with weight loss. In fact, according to a new study at the University of Pittsburgh, people wearing activity trackers lost about half as much weight in a 24-month randomized trial than those who weren't wearing them.

How could this be?

First, let's take a look at the study led by John Jakicic, chairman of Pitt's Department of Health and Physical Activity and published last month in The Journal of the American Medical Association. 

The study followed 470 people ages 18-35 with a body-mass index between 25 and 39. All participants were placed on low-calorie diets and were prescribed increases in physical activity as well as group-counseling sessions on health and nutrition. 

After the first six months, participants were divided into two groups. One continued receiving monthly health counseling, while the other received a wearable device to monitor diet and physical activity.

The results? Those who utilized wearable activity trackers lost 7.7 pounds on average, compared to 13 pounds for those who only participated in behavior-based health counseling.

"While usage of wearable devices is currently a popular method to track physical activity -- steps taken per day or calories burned during a workout -- our findings show that adding them to behavioral counseling for weight loss that includes physical activity and reduced calorie intake does not improve weight loss or physical activity engagement," Jakicic said. 

Having coached nutrition clients who like to rely on wearable devices, I have a couple of theories for why this happened. First, whether you're counting calories in or calories out, calculating energy balance is a risky, error-prone undertaking. Specifically, as illustrated in this infographic from Precision Nutrition, consumer fitness trackers are off by as much as 30 percent when it comes to measuring calorie expenditure. Due to other factors, such as genetics, sleep, hormones and the macronutrient breakdown of your food intake (protein requires more energy to digest than carbs and fats), you could be looking at as much as a 25 percent error in measuring your energy balance.

I have encountered clients who use activity trackers and sync them with My Fitness Pal, thinking the more closely they monitor their energy balance, the more successful they will be at losing weight. In addition to how imprecise and error-prone calorie counting is, there's another problem: When people see the massive amount of calories they supposedly just burned in a given workout, they often view it as a license to pig out with a huge meal. In fact, you can set apps like My Fitness Pal to tell you how many extra calories you've supposedly earned that day.

If you're trying to lose weight and/or fat, not a good idea.

As the study shows, the most effective path to consistent and sustainable weight loss is a behavior-driven approach that includes learning how to make better food choices without apps, spreadsheets, scales and error-prone calorie counting. 

"While usage of wearable devices is currently a popular method to track physical activity ... these devices should not be relied upon as tools for weight management in place of effective behavioral counseling for physical activity and diet," Jakicic said.

Would you like to learn more about how we coach our clients to sustainable weight loss using a proven curriculum that focus on behavior and lifestyle change instead of gimmicks, extreme diets and fads? Let us know how we can help.