Fitness Trackers Are ‘Poor’ At Measuring Calories Burned

Don’t trust that fitness tracker data… While most are good at measuring heart rate, research shows they are poor at measuring calories burned.

Stanford University scientists took 60 volunteers and seven wrist-based fitness trackers - the Apple Watch, Fitbit Surge, Basis Peak, Microsoft Band, PulseOn, MIP Alpha 2 & the Samsung Gear S2.

Out of all this data collected, based on the people walking, running and cycling, they found that while the heart rate monitoring was accurate with an error rate around 5%, the calorie tracking side of things was quite a way off from being accurate!

So why is the error rate way over 20% on calorie tracking (or energy expenditure)? Well, according to Dr Euan Ashley, co-author of the study from the department of cardiovascular medicine at Stanford University, says they give rough estimates.

This could be a big problem to many users, who rely on the tracker’s measurements to dictate their diet. Just because it said you lost 400 calories after that run, doesn’t actually mean you’ve got an extra 400 calories to play with…

While heart rate measurement has progressed at a rapid rate over the last few years, he added that tech behind energy expenditure is “not quite there yet.” This is because it’s impossible to estimate calories burnt with any real specificity due to many different variables like height, weight., body fat, heart rate and many many more.

But is this as big of a problem as the study suggests? Well, yes and no. To those who have specific macros and body fat % goals to hit, then a greater level of accuracy is vital. 

Dr David Ellis, lecturer in computation social science at Lancaster University, said it is next-to impossible to find the exact source of error, since “manufacturers do not share algorithms [which are constantly updated].”

This is why the research asks for companies to be more transparent and publish their own tests of accuracy, to hold them to a higher standard.

 Cardiology researcher Euan Ashley and his team conducted a study to determine how accurately seven types of fitness trackers measure heart rate and energy expenditure.

Cardiology researcher Euan Ashley and his team conducted a study to determine how accurately seven types of fitness trackers measure heart rate and energy expenditure.

However, to the standard person looking, this really is a none-issue. I don’t need 100% accuracy and many others don’t. The fact it’s encouraging people to exercise outweighs this flaw greatly.

And most people buy fitness trackers as a fashion item/family Christmas gift, so don’t worry - this isn’t a deal breaker. Just use common sense when it comes to healthy eating and let the fitness tracker tell you when you hit 10,000 steps.