Video by trainbloom

Because when I see somebody wearing an Apple Watch and they post it after their workout, really? You burned 1,500 calories in an hour? Exactly how inaccurate are these? Well, lucky for us, Stanford researchers wanted to find out. They took seven of the most popular wrist-worn calorie tracking devices and put them on people

for a few different workouts to see how accurate they really were. And the results even shocked the researchers. Because although these things were accurate at measuring things like your heart rate and step count. When it came to measuring calories, even the best one was off by almost 30% and the worst off by 93%.

Meaning if a tracker says you burned a thousand calories during a workout, you might have only burned a few hundred. And yeah, technology has gotten better since this study came out a few years ago, but the technology wasn't the problem. The real issue is that these devices only use about five metrics to come up with that number.

Where in reality, there are hundreds that influence how many calories you burn, things these devices can't take into account. But that's all okay, because knowing exactly how many calories you burn during a workout doesn't really matter. And there are way more important numbers to pay attention to if you want to lose weight.