Validation of the Fitbit wireless activity tracker for prediction of energy expenditure.
OBJECTIVE
The purpose of this study was to examine the accuracy of the Fitbit wireless activity tracker in assessing energy expenditure (EE) for different activities.


METHODS
Twenty participants (10 males, 10 females) wore the Fitbit Classic wireless activity tracker on the hip and the Oxycon Mobile portable metabolic system (criterion). Participants performed walking and running trials on a treadmill and a simulated free-living activity routine. Paired t tests were used to test for differences between estimated (Fitbit) and criterion (Oxycon) kcals for each of the activities.


RESULTS
Mean bias for estimated energy expenditure for all activities was -4.5 ± 1.0 kcals/6 min (95% limits of agreement: -25.2 to 15.8 kcals/6 min). The Fitbit significantly underestimated EE for cycling, laundry, raking, treadmill (TM) 3 mph at 5% grade, ascent/descent stairs, and TM 4 mph at 5% grade, and significantly overestimated EE for carrying groceries. Energy expenditure estimated by the Fitbit was not significantly different than EE calculated from the Oxycon Mobile for 9 activities.


CONCLUSIONS
The Fitbit worn on the hip significantly underestimates EE of activities. The variability in underestimation of EE for the different activities may be problematic for weight loss management applications since accurate EE estimates are important for tracking/monitoring energy deficit.
Dept of Kinesiology, University of Massachusetts, Amherst, MA.
Jeffer Eidi
JE
Sasaki
Amanda
A
Hickey
Marianna
M
Mavilia
Jacquelynne
J
Tedesco
Dinesh
D
John
Sarah
S
Kozey Keadle
Patty S
PS
Freedson
D000328:Adult; D002149:Energy Intake; D004734:Energy Metabolism / Q000502:physiology*; D005080:Exercise Test / Q000295:instrumentation*; D005260:Female; D006801:Humans; D008297:Male; D018670:Monitoring, Ambulatory / Q000295:instrumentation*; D012420:Running; D016138:Walking; D059015:Wireless Technology / Q000295:instrumentation*; D055815:Young Adult