Are Fitness Trackers and Scales Accurate?
No, fitness trackers and scales are NOT accurate
Yes, unfortunately you read that right. Your wrist band that is telling you you’re burning 1500 calories during your workout is very inaccurate. Same goes for cardio equipment. Your hour on the elliptical is not burning 1000+ calories. Clients come to us all the time asking should I be adding 500 extra calories to my diet because I’m burning so much during my workout? And the simple answer is no. And that’s because you’re not actually burning that many calories. Fitness trackers and cardio equipment are notoriously inaccurate in their estimation of calorie burn. Numerous studies have been done to prove this as well. Let’s look at a little bit of the research.
A study done at Stanford in 2017 looked at 7 fitness trackers (among them were the popular Apple watch and Fitbit) and how well they estimated energy expenditure. The study found that even the most accurate tracker was off by an average of 27%…and the least accurate was off by a whopping 93%!!! And this was tested under several conditions – walking, running, and cycling. A similar study was done in 2016 showing estimates of energy expenditure were poor at up to 43% off as was a study in 2018.
Do they track anything accurately?
However, fitness trackers are relatively accurate in their assessment of steps. And like we’ve noted in a previous blog, steps and NEAT (non-exercise activity thermogenesis) are super helpful when trying to regulate your weight. So keep tracking those steps on your Fitbit!
What about body fat scales?
Along those same lines, we hate to break it to you, but those body weight scales and handheld BIA (bioelectrical impedance analysis) machines you use at the gym do not accurately track your body fat. BIA scales are supposed to estimate the relative percentages of different tissues and substances within the body by sending a weak electrical impulse through the body and determining the varying levels of resistance from the different tissues.
However, studies show that they are not accurate. In fact, even the most “accurate” forms of body fat testing like the BodPod and DEXA scans aren’t all that accurate. The only true way to determine your body fat is to have an autopsy which I don’t think is ideal because, well, you’d be dead. Really, the scales seem to interpret change in body water, not fat mass. Check out this article to read more about the inaccuracies of these scales.
So, are we saying to toss all of these tools out the window then? No not necessarily. But know what they are and what they aren’t. Just a tool in the toolbox which may be able to show you some trends over time.