vs  

Let me put the disclaimer right here at the top…I wear a Fitbit Flex everyday. I wore three Nike+ Fuelband SE trackers in succession until I gave up on the product every being able to withstand my usage. I’ve been somewhat compulsive about tracking my levels of activity for several years and swear by the data I’ve gathered.

Throughout all the tracking, I’ve come to the realization that just like on the TV show Whose Line Is It Anyway, “…everything’s made up and the points don’t matter”. Well, not exactly made up, but the numbers generated by the fitness trackers can’t be compared to each other. The only way that the numbers matter is when compared over time using the same tracker.

It’s not really that hard a concept to grasp, if you don’t get all caught up in accuracy. All fitness trackers measure activity using some measure of movement. Regardless of whether they’re from Fitbit, Nike, Jawbone, Garmin, or any of the other manufacturers, the trackers use an accelerometer to measure movement. Then they convert the movement to steps, calories, or points. In short, they take a measurement of some kind of motion from some part of your body and they run it through a conversion to get an estimate of your activity. Based on your height and weight they may even take the estimate further and generate an estimate of the calories that your burned or maybe the steps you’ve taken.

Let’s face it, if you wear a band on your wrist there’s going to be some margin of error when you try to convert that into steps. One day you might swing your arm a bunch, the next you may move your arm very little. If you’re carrying something in your hands, you might be walking without moving your arm very minimally. If you’re carrying a kiddo with the arm bearing the tracker, you might not get credit for any steps or calories burned. From experience, I can tell you that carrying an 11-month-old burns a heck of a lot more calories that walking without those extra 25 pounds in your arms. But my fitness tracker doesn’t have a way to measure the weight I’m carrying. So the estimate of the calories I’m burning will be less accurate. The estimate of the number of steps I’ve taken will be less accurate. In fact, the estimates will be wrong.

But so what?

In the recent article from The Daily Mail, Anna Magee pretty much throws the entire industry under the bus. She exposes the fact that the accuracy of the compared trackers varies wildly. In fact, the trackers don’t come close to each other, and don’t really come close to the controlled measurements of the University of Bath labs. Her final analysis potentially steers her readers away from using any fitness tracker. She states:

This experiment has made me question my devotion to fitness trackers. I’m not the only one. Recent research found that although sales are on the up, like gym memberships, they’re soon ditched, with a third of people abandoning theirs after only six months. I’m going back to that simple equation of moving more and eating less. It’s low-tech — but at least I know it works.

Source: http://www.dailymail.co.uk/femail/article-2925963/The-fitness-gadgets-make-fatter-claim-count-calories-burn-test-shows-theyre-wildly-inaccurate.html#ixzz3Q2nSt0Zk

But she leaves her readers with an underlying problem. How the heck will she know if she’s “…moving more…“? You can’t do that by guessing that you moved more. You need some way to measure how much you’re moving. You need to measure your activity each day to know whether on Monday you moved a lot and Tuesday you didn’t. As a committed data person, I know that I personally need numbers to compare. I just don’t understand how you can know that your moving more if you’re not measuring how much you move.

Frankly, I don’t care what number you choose…Fuel Points, calories, steps, unicorn sneezes. They will all work if you compare the same numbers across time. If you choose calories, regardless of what tracker you’re using, if the software estimates that you use 20% more calories on Monday than you use on Tuesday, you can be pretty sure that you were more active on Monday. Were you exactly 20% more active…I can’t tell you. But I know that once you reach the point of statistical difference, you’re going to be able to know that you were moving more.

And when you get right down to it, we’re all too sedentary. I know that I sit around too much. I also know that when my Fitbit software sends me a message at 5:00pm telling me how many more steps I need to reach my daily goal (currently 10,000 per day), I can tell whether I’ve been sitting on my butt or moving around most of the day. When I get that message that says I’ve overachieved my goal by 2,363 steps for the day, I’m motivated that I actually exceeded my own expectations. It’s a bit silly, but I get a bit of a kick out of having achieved and exceeded my goal. Frankly, it’s motivational.

By the same token, if I get the message from my Fitbit that I’m 4,000 steps from my goal, I know that I’ve been slacking during the day. I either have to get my backside in gear, or accept the fact that I’m not going to make my daily goal. Since I’ve been using my Fitbit I’ve made my goals vastly more than I haven’t. Some days it’s taken some extra work. Some days I’ve hit my goal by mid-afternoon. Some days I’ve missed the mark. But on everyday, I can look at my numbers and compare them to the other days.

So I would recommend that anybody who reads the story from the Daily Mail consider what they’re trying to achieve. If you’re looking for a foolproof, 100% accurate way of measuring the steps or calories that you burn in a day…strap on the Indirect Calorimetry machine gear and measure away. On the other hand, if your goal is to move more, then consider using some sort of less obtrusive fitness tracker and compare the results from one day to the next. Pick your measure that you want to improve, whether calories or steps, and have at it. Just realize that you can’t compare your numbers to anyone else, even if they’re wearing the same fitness tracker.

But isn’t the point for you to make a better you?

To that end, my Fitbit Flex is doing exactly what I need it to do. Giving me some way to compare myself and my activity from day to day. And giving me a nudge or some motivation regarding how much I’ve actually moved in a day.