In April 2017 researchers from Australia published the results of their study to assess the accuracy of energy expenditure estimations made by the Fitbit One, Garmin Vivofit and Jawbone UP activity trackers. Fourteen adults wearing an activity tracker both walked and ran on a treadmill and the estimation of energy expenditure as assessed by the tracker was compared to a validated independent assessment. Results showed that the energy expenditure estimates from the tested trackers were all very similar to the independent assessments across all walking speeds but only the Garmin Vivofit had similar energy estimations across running speeds. The researchers concluded that although such devices are not suitable as research measurement tools for recording precise and accurate energy expenditure they may be suitable for behavioural change interventions as they provide feedback to the user on trends in energy expenditure.
Price K et al. Validation of the Fitbit One, Garmin Vivofit and Jawbone UP activity tracker in estimation of energy expenditure during treadmill walking and running. J Med Eng Technol. 2017 Apr;41(3):208-215