Smartwatch calorie accuracy is assessed

Investigators evaluated energy-expenditure estimates from 4 consumer devices using indirect calorimetry during controlled cycling in Hispanic adults.

Category	Detail
Condition	Calorie expenditure estimation using smartwatches
Key Mechanisms	Comparison of smartwatch estimates against indirect calorimetry using COSMED K5 metabolic system.
Target Population	Hispanic adults aged 18 to 50 years with varying body fat percentages.
Care Setting	Controlled experimental setting.

Smartwatch estimates of physical activity energy expenditure varied by device.
Higher body fat percentage correlated with greater estimation errors.
Fitbit produced implausible estimates exceeding 450% of the criterion value.
Garmin and Samsung overestimated energy expenditure relative to indirect calorimetry.
No significant association found between Fitzpatrick skin type and estimation error.

Use indirect calorimetry as a criterion for validating smartwatch calorie estimates.

Consider body fat percentage when interpreting smartwatch calorie expenditure data.

Regularly assess the accuracy of different smartwatch devices in various populations.

Potential for significant overestimation of calorie expenditure by certain devices.

Hispanic adults aged 18 to 50 years with varying body fat percentages.

Device-specific differences in calorie estimation accuracy should be considered.

Validate smartwatch calorie estimates with indirect calorimetry in diverse populations.
Account for body fat percentage when using smartwatch data for health assessments.
Be cautious of implausible estimates from devices, particularly Fitbit.