Study Finds Smartwatches Overstate Calorie Burn by 15%-25% as Higher Body Fat Worsens Errors
Updated
Updated · New Atlas · Sep 3
Study Finds Smartwatches Overstate Calorie Burn by 15%-25% as Higher Body Fat Worsens Errors
3 articles · Updated · New Atlas · Sep 3
Summary
58 participants wearing four popular smartwatches during cycling tests logged calorie-burn estimates that ran 80 to 110 calories high on average versus a laboratory analyzer.
Higher body-fat percentages made those readings markedly less reliable, while researchers found no noticeable accuracy differences across participants’ skin tones.
Samsung Galaxy Watch 5 and Garmin Forerunner 955 showed the strongest systematic overestimation; Apple Watch Series 8 was closer, and Fitbit Sense 2 posted no average bias but 13% implausible estimates.
Researchers said the inflated numbers could leave users hundreds of calories off over a week, undermining weight-loss plans even if the devices still help track broader fitness trends.