Study finds Garmin worst among four brands at counting calories

A study from Florida International University tested the Apple Watch Series 8, Fitbit Sense 2, Samsung Galaxy Watch 5 and Garmin Forerunner 955 against a lab-grade COSMED K5 device. Fifty-eight adults wore all four watches during a ten-minute interval session on a recumbent bike, rotating wrist positions to remove bias. Garmin's calorie count missed by an average of 68.61 kcal, a 77.6 percent error, the worst of the group. Fitbit looked accurate only because researchers discarded its worst readings; put back in, its average miss jumped to 128.6 kcal. Error rose with body fat for every brand, but faster for Garmin and Fitbit than Apple. Researchers concluded none of today's watches are reliable enough for weight management.