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Study Shows Calories Burned May Be Wrong On Fitness Trackers

According to a recent study by researchers at Stanford, the number of calories your fitness tracker says you've burned is likely inaccurate.

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Whomp whomp.

We’re sorry to be the bearers of bad news, but if you have one of the fitness watches recently tested for caloric expenditure accuracy, your fitness tracker might be lying to you…in a way.

A study conducted by researchers at Stanford was published earlier this year scrutinizing numerous popular fitness watches, most of which used two widely accepted methods of estimating calorie burn. The watches tested included the Apple Watch, Fitbit Surge, Mio Alpha 2, Basis Peak, Microsoft Band, PulseOn and the Samsung Gear S2. The results offer some interesting insights–and by “interesting” I mean painful, because the results of such fitness trackers can be grossly overestimated.

Related: How To Get The Most Out Of Your Fitness App

Here are the study’s three big conclusions:

  • The most accurate of the seven watches tested was off by roughly 27 percent.
  • The least accurate was off by an astounding 93 percent!
  • Six of the seven trackers accurately measured users’ heart rates within 5 percent.

The good news (other than the trackers’ heart rate accuracies) is that Garmin Connect, Strava and other training apps might be a bit better, but the numbers they report depend heavily on the information you provide. To ensure that accuracy, we have these three tips:

1. Do not lie about your weight.

Seriously: the more accurate the data you include about height, weight, gender and heart rate maximums, the better the internal algorithms can spit out legitimate numbers. Also, wearing a heart rate monitor that syncs to your device allows for improved accuracy in calorie burn estimations.

2. Keep your body guessing.

The kicker is that, the fitter you are, the more efficient your body is—which equates to less energy expenditure and fewer calories burned. You need to constantly keep your body guessing, trying new and different forms of exercise or a variety of training methods (like speedwork, hill repeats, tempo runs, etc) to achieve a bigger calorie burn.

3. Know your stuff.

The last and probably most important factor is knowledge. If the number seems too good to be true, it probably is. Besides, there is a lot more to weight loss (if that’s your ultimate goal) than the number of calories you burn.

In the meantime, don’t rely too heavily on your watch to tell you the truth in numbers!


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