Fitness Trackers – Wearable Tech High Margin for Error

Portions from MobihealthNews – A new paper published yesterday in JAMA Internal Medicine shows that, when it comes to measuring energy expenditure, many leading fitness trackers have a margin of error of about 200 calories per day in either direction.

The study was conducted by Japanese researchers led by Haruka Murakami from the National Institute of Health and Nutrition in Tokyo. Nineteen participants, aged 21 to 50, wore 12 fitness trackers a piece, a mix of popular consumer devices (Fitbit Flex, Jawbone UP24, Misfit Shine, Epson Pulsense PS-100, Garmin Vivofit, Tanita AM-160, Omron CalorieScan HJA-403C, and Withings Pulse O2) and devices more often used in healthcare (Panasonic Actimarker EW 4800, Suzuken Lifecorder EX, Omron Active style Pro HJA-350IT, and ActiGraph GT3X).

This study examines the accuracy of total energy expenditure estimates made by wearable devices compared with measurements made using the metabolic chamber and doubly labeled water methods.

Accurate estimation of energy expenditure is a key element in determining the relationships between aspects of human behavior, physical activity, and overall health.1,2 Although wearable devices for estimating energy expenditure are becoming increasingly popular, there is little evidence regarding their validity.3,4 This study was performed to examine the validity of total energy expenditure estimates made by several wearable devices compared with gold standard measurements for a standardized day (metabolic chamber method) and free-living days (doubly labeled water [DLW] method).ama-wearablesIn the metabolic chamber test, the Withings and Jawbone devices underestimated expenditure by about 270 calories while both Omron devices overestimated calories by about 200 calories. The other devices all fell in between that range, with the Panasonic and Epson devices the closest to the standard.

In the urine test, on the other hand, all the devices underestimated calorie output, by margins ranging from 69 calories short (the Omron Active Style Pro) to 590 calories short (the Jawbone UP24).

Researchers noted a few factors that might have contributed to the disconnect, including the fact that participants couldn’t wear the trackers all the time. They also noted that they tested only a healthy weight population, and that future studies should include overweight participants as well.

As the saying goes, “when the going gets tough, the weird turn pro” time for these devices to be really professional and really do their job.  In addition, your fitness tracker should be used with MedsMinders to track your vitamins, supplements, and other meds.