Your fitness tracker is (probably) lying to you

We live in a golden age of health tracking. There are apps to track your steps, to input food and drink intake, plan your rise to become fully active from that spot on the couch, and lots more. If you're really serious about it, you can buy an accessory for your phone that helps track a whole bunch of different fitness activities. The inexpensive models can count your steps and tell you how far you've gone, the mid-range models will help you with segment break downs as you run or mile counters as you ride your bike, and the most expensive models are fully waterproof and will track your swimming and all sorts of other things.

Want to know what all of these fitness trackers have in common? They're all liars, because none of them are human-proof and most of them are missing key features to ensure accuracy.

If you're running outside, GPS makes a huge difference

I run 5K every morning by myself, and then my son walks 5K with me right after. Most mornings, I strap on my Fitbit Ionic and my son his Fitbit Ace 2. But occasionally I forget to charge my tracker after a couple of days and just take my phone instead. I have Google Fit, after all, and it's supposed to do live fitness tracking within the app even if I don't have a tracker on my wrist. In theory, this is great because it reduces the barrier to entry for fitness tracking to zero. You already own the phone, so you already have a way to track your activities and push yourself to do more.

Step counting without GPS is a guess, and frequently not a good one.

At the end of my 5K run, the same route I take every single morning, Google Fit said I'd only run a little over two miles instead of the 3.1 miles I know it was. I know this because my Fitbit Ionic is a GPS-enabled fitness tracker, so it gives me a more exact measurement of my movement. There is a way to have Google Fit track your activity with GPS, but I never realized the difference between having it and not was so significant. My phone wasn't the only fitness tracker lying to me that morning; when my son's Fitbit got to the end of the walk, it also said we'd only covered a little over two miles during this active time.

Step counting without GPS is a guess, and frequently not a good one. There's no way for the tracker to know how wide our gait is, because it's different for every person. Instead, you get an average based on the information you've provided. Google Fit asks for my height and weight, so that distance information was assembled based on Google's guess. Fitbit doesn't have any physical information for my son, so it's guessing based on the gait of a child. In both cases, these guesses were way off. There's every chance the same is happening for you, which is why you should have GPS with your fitness tracker.

Eliminating false positives with step counters is impossible

You know that thing you do when you're in a traffic jam and your car hasn't moved in over 25 minutes, so you've just got your music up loud and you're sitting there jamming out an epic drum solo in the driver's seat for everyone around you to enjoy? No? Just me? Fine, whatever.

I'm six minutes into my imaginary drum session, which in case you were wondering sounds way better than my real life drum sessions, and my Apple Watch starts buzzing on my wrist. Congratulations! You've completed your rings! While sitting down, for over an hour, the fitness tracker on my wrist was under the impression I was not only standing up but fully active and doing something worthy of being counted as physical activity. This isn't something exclusive to the Apple Watch by a long shot, my son loves laughing at his Fitbit Ace 2 as we drive, because he can look down and watch as the step count on his wrist climbs as I run over bumps. When he's trying to compete with his sisters to see who has the most activity that day, a 30-minute car ride in some areas is basically a free 800-1000 steps for him.

None of this is to say you shouldn't own a fitness tracker. On balance, your tracker can easily be a force for good in your day-to-day.

Step counters, or pedometers, typically count a single step as the feeling of impact. Old school pedometers had a physical piece that moved up and down, and when that movement happened a step was recorded. Most these days use digital accelerometers, measuring motion and impact from your wrist. But since very little is done to detect and eliminate things that aren't steps, these Total Step numbers or that large ring on the Apple Watch frequently means very little.

The only real solution here is to rely on the data from individual activities. When you tell your watch or your phone to capture a specific kind of activity, it's relying on very specific kinds of motion to give a more accurate representation of your movements. Those events are the most significant indicator of physical activity, especially when paired with a heart rate monitor to apply some additional context to your walk. This way, you're combining steps and environmental movement like vertical inclines with heart rate to paint a picture of how active you are and how that activity has impacted your body.

Fitness trackers are a small part of a bigger picture

None of this is to say you shouldn't own a fitness tracker. On balance, your tracker can easily be a force for good in your day-to-day. For individual things, they can be fantastic ways to see how you improve and give you a better understanding of how healthy you are. But the most popular fitness trackers are marketed as these whole day health monitors, and regardless of manufacturer, I find the notion disingenuous.

Fitbit's 10,000 step a day goal is based on junk science while still being a cool goal to set for yourself. None of these systems include or recommend a rest day after you've done something extremely physical like participate in a triathlon or biked a Century or run a full marathon, which is nuts. Google's "Heart Points" system in the updated Fit app is interesting, but still not something you should use as a health consultant.

Ultimately these things are great individual use tools, often with great extra features like pairing to your phone for calls or receiving notifications, and not really a way to monitor your whole self when it comes to health and wellness. And as long as you pick the right hardware for your needs, fitness trackers can still be a hugely important part of your health journey.

Russell Holly

Russell is a Contributing Editor at Android Central. He's a former server admin who has been using Android since the HTC G1, and quite literally wrote the book on Android tablets. You can usually find him chasing the next tech trend, much to the pain of his wallet. Find him on Facebook and Twitter

  • As you say, the data can't be trusted so they are of no use to me personally. I see these fitness trackers as little more than a gimmick. But that gimmick can be an incentive or motivator for some people to exercise more so in that sense they can serve a purpose.
  • That's not... exactly what I said. As a whole day, whole health system these trackers are problematic. For individual workouts the right tracker can be very useful.
  • If my "fitness tracker is (probably) lying" then how can it be trusted? That is the thesis of this article, no? I will grant you (because I'm a benevolent internet commenter :P ) that you did say they can be useful in the right context. Still not useful enough for me to bother with.
  • I always say use it as a guide and estimate, not for exact tracking. I have the fitbit versa and I enjoy tracking things in general.
  • Did you read the article or just the headline? It lies about *some* data, but there's some data that it provides which is fairly actionable and reliable.
  • Did you read my whole post or just the first sentence? "Some data" that is "fairly reliable" is still not useful enough for me to bother with.
  • I use mine just as a guide. The Galaxy Active is tracking how much I run, etc. when I officiate sports. Is it 100% accurate? No. However, it does help me accomplish my goals.
  • That's a bit unfair, there's a difference between lying and providing inaccurate information. They can definitely be a double edged sword... It's probably a good thing if they can get people off their arses, but it's definitely important that people understand they aren't particularly reliable, especially when it comes to health as opposed to fitness.
  • That distinction exists in the article. I interpreted the headline as somewhat tongue in cheek. I don't think the author ever meant to imply they're explicitly lying. The closest to that sentiment is when the author states that the manufacturers are basically overselling what the devices provide.
  • I'm not looking for 100% accuracy out of my fitbit versa like a pro device. But what I do look for is trends and consistency. So, let's just say that I average 8000 steps and 45 "active minutes" per day on it. Is it exactly 8000 steps and 45 active minutes? probably not. But I use that as a baseline. if there's a variance of a couple hundred steps and a couple minutes, then I know it's about the same. but if I have a day where it tells me I did 5000 steps and only 10 active minutes, well obviously I was less active that day. Same goes the other way. If the numbers are significantly higher, clearly I've been more active. To me, it's all about looking at your averages, and seeing if your activity is above or below those averages. It might not be 100% accurate to actual professional data, but when you use it against itself and look at trends, that's where I get a ton of use/data out of it.
  • Exactly. Looking back through years of step data on my Garmin app combined with biometrics you end up having some very powerful insights..provided you are also tracking what you eat!
  • They can't recognise or track my exercises during weight training and neither during running. Even getting one's heart rate at rest is erratic ("Please clean the sensor and repeat"). Thus I don't have one. To me they're just cheaper versions of smart watches. Suitable mainly for notifications and calls. Which my Gear S2 Classic still does extremely well.
  • I have the Fenix 5X. That can track quite a few different strength training exercises (obviously you hit a snag on unilateral exercises sometimes. But even if you turn off the "automatic rep counting", its still very useful and can easily take the place of a workout log book.
  • We had this problem on a recent trip to Disney World. My wife's apple watch was always short in mileage covered at the end of the day compared to my Gear s3 and it wasn't a small discrepancy. We just kind of figured that are actual distance was somewhere between her number and mine.
  • My wife wears one. I don't know how accurate it is but it does keep her motivated and gives her an idea of how active she is day to day.
  • My Galaxy watch 42mm says I burn about 800 calories sleeping but a ten hour shift driving for FedEx I only burn 250. Apparently stairs use less energy than being unconscious.
  • *immediately changes workout routine*
  • It sounds like it may be counting different things. 800 resting calories, but 250 active calories. Resting calories are just what you burn to sustain your life functions. Active calories are due to you doing extra. 250 still sounds pretty low though for the amount of walking i'd imagine you'd do. I wonder if carrying packages sometimes cancels out steps cause you're not moving your arm normally.
  • Could be. But I only have one choice for calories burned. As for the workout it should be counting steps as well as pulse. Maybe it's just not that smart.
  • TL;DR Fitness trackers are good estimation devices and guides rather than absolute truth
  • Well, I bought a Ticwatch E because I wanted an inexpensive smartwatch to try out, with no concern for fitness tracking. That being said, I've measured it by manually counting steps, and it's more accurate than I expected, registering 198 steps compared to 200 actual steps. It does have it's own internal GPS, and that helps as you mentioned. But regardless of accuracy, it does encourage me to take stairs more often and to walk more.
  • Great write-up Russell. I like them as it is some form of measurement and the data is helpful to me to verify my progress. The reality of 10,000 vs 9,000 steps is not something i care about. A busy day for me is 10k, but a work day, at my desk is lucky to break 3k. The reminder for me to get off the couch is worth the price of the wearable. The GPS to add accuracy makes sense.
  • If you're serious about accurate fitness tracking or accurate as reasonably possible then simply don't buy a cheap device or a watch that's predominantly a smart watch with fitness tracking added on like Fitbits, Samsung GearS and Apple Watches. They're OK but can't be trusted like a good Garmin, Suunto or Polar etc.
  • Interesting article. I recently came to the same conclusion. I had some heart issues within the last year that the Apple Watch detected. I offered the data to my cardiologist and he politely declined. The Apple watch was one factor that convinced me to see my doctor. After that, I paid attention to my exercise and heart rate and soon discovered that the Apple watch was not the magic elixir. All of these trackers are not perfect and for the most part are all relative. That it why I elected to go with a Samsung product this time around. I use it primarily to determine how active I was from one day to the next as well as a motivational tool. I glance at the data but no longer obsess over it
  • Great title. Lured alot of people including me while the article is just stating common information about trackers. It's been said, and is quite obvious that these trackers show you roughly how active you've been and like others say, they are good motivators.
  • I bought under armour with a built-in pedometer and gait tracker. I recommend this for all runners. I also own the ticket heart rate monitor. With both of these I get very accurate readings.
  • My Garmin 935 gets pretty darn close to an accurate heartrate for me (based upon comparison with the real version at doctor's appointments), recommends how many hours to take off after every exercise session, is a remarkably accurate step counter (I've counted many times, while both walking and running), etc. All of those data points are interesting, and the steps are a useful indicator for days when I should be moving more (and I absolutely find it useful to have my watch vibrate and tell me to get up and move if I've been sitting for too long). I don't count on it to be a replacement for a trip to the doctor, and can't imagine anybody doing that. In short, if you want to have a sort of accurate accounting of a few health data points, invest in a real activity tracker, not a smart watch with a few clever tricks in the app. if you want a smart watch, invest in that (my Garmin is what I refer to as a semi-intelligent watch. It can push notifications if I allow it to, but that's about it...).
  • So, I guess we need to follow this up with a measured-course test and see which ones do a better job. Russell? 😉
  • This is a minor point, but for accuracy:
    "None of these systems include or recommend a rest day"
    This isn't true. The garmin line of wearables, at least on the higher end, do actually tell you recommend rest times and suggested intensity level following recorded events.
    The forerunner series is explicitly designed for triathlons, but it's quite a bit more expensive than an apple watch too.
  • Dang, run 5k and then walk 5k every morning?! That's a lot of Ks! You must look a lot different today than the Russell Holley of the past. Well done!
  • "None of these systems include or recommend a rest day after you've done something extremely physical like participate in a triathlon or biked a Century or run a full marathon, which is nuts. " That isn't true at all, at least on Garmin devices. After every activity, Garmin determines a "Recovery Time" based on the stats of the activity and your calculated fitness. This pops up in the stats screen after every workout when you save the workout, and you can go to the screen on the watch. See, e.g.