Smartwatch calorie tracking accuracy study

Researchers at Florida International University conducted a study published in ‘PLOS One’ regarding the accuracy of calorie tracking in popular smartwatches. By comparing devices such as the Apple Watch Series 8, Fitbit Sense 2, Samsung Galaxy Watch 5, and Garmin Forerunner 955 against a professional COSMED K5 metabolic analyzer, the study identified significant discrepancies in energy expenditure estimates.

Findings revealed that none of the tested devices were fully accurate, with typical errors ranging between 15% and 25%. While the Apple Watch Series 8 demonstrated the least deviation, Garmin and Samsung devices tended to overestimate caloric expenditure. Fitbit data was noted for being inconsistent or providing implausibly low readings.

The research highlighted that accuracy decreases as a user's body fat percentage increases, suggesting that manufacturer algorithms may not sufficiently account for higher body fat levels. Lead author Jason Kostrna cautioned that users should not treat these estimates as precise measurements, as overestimations could lead to unintended caloric surpluses for those managing weight.