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The Pros and Cons of Wearable Fitness Trackers

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Last Updated on December 21, 2019 by Heather Hart, ACSM EP, CSCS

Wearable fitness trackers are not a new concept.  Pedometers have been dutifully worn on the waistband of fitness seekers for decades now.  However, over the last decade, wearable fitness trackers have become exceedingly more popular as the technology and data they provide users have become more in-depth. As the technology progresses, so do the claims of what these devices are capable of. But are they too good to be true?  Let’s take a look at a few pros and cons of wearable fitness trackers.

Four Pros and Cons of Wearable Fitness Trackers

Wearable trackers have evolved from simple pedometer style to technology that utilizes everything from accelerometers, heart rate readings, body temperature measurements, GPS systems, and so much more.  These devices, usually worn on the wrist, can measure everything from calories burned, distance covered, varying activity levels throughout the day (such as sedentary periods versus vigorous activity), and even sleep efficiency.  Typically paired with an online dashboard or phone app that allows you to compare this data versus input of food intake, these wearable fitness trackers are touted as a key to successful weight loss and fitness. 

Fitness trackers have become synonymous with fitness and weight loss goals. Are they too good to be true? Let's analyze the pros and cons of wearable fitness trackers.

Pro: An Activity Reality Check

Think you move a lot during the day?  You might want to think again.  I spend the first half of my day behind the computer screen writing articles such as this very one you are reading.  Then, I spend the second half of the day at the gym, both completing my own workouts and then manning the front desk and attending to members and the facility. Naturally, I assumed I was EASILY clearing 10,000 steps a day.  It wasn’t until I started regularly wearing a fitness tracker that I realized I was wrong.

Imagine my shock when I noticed that on average, I barely cleared 1,000 steps before lunch. And that includes numerous trips to the kitchen (I’m a hungry runner!) and to the bathroom.

fitbit graph inactivity
In this graph from my Fitbit dashboard, you can see the 4 hours of painful inactivity, while I sat at my computer desk.

We all know that sitting is hazardous to our health.  But new research is showing that even those of us who meet our weekly recommended activity levels can still have massively negative health effects from sitting too much.    Fitness trackers are a wonderful tool in giving you a visual reality check of how active…or inactive…you really are. Thus, the fitness watches become an accountability tool to your true activity levels.

Con: Accuracy of Caloric Burn

Are wearable fitness trackers accurate when it comes to the number of calories burned? In short: not likely.

Here’s how the estimated caloric expenditure is calculated on your fitness tracker.  You enter your height, weight, and age into the computer (or app) which is then uploaded to your tracker.  These variables are then used to calculate what is known as your basal metabolic rate, or BMR.   By definition, BMR is the amount of energy expended while at rest in a neutrally temperate environment, in the post-absorptive state (meaning that the digestive system is inactive, which requires about twelve hours of fasting). 

In other words, how many calories your body burns per day just to maintain itself. That does not include added activities such as exercise, walking, or even the act of digesting food.    The BMR that your tracker calculates based on your height, weight, and age is then thrown into another equation based upon the detected activity you complete according to the tracker. The watch/app then uses all of this data to come up with an end estimate of daily caloric expenditure. 

Let’s focus on the word “estimate” for a minute.

While this topic has been thoroughly researched, the BMR calculation, and the added activity equations, are still an estimate based on the average person (i.e., the average of the individuals studied).    Studies show that the BMR equation alone can have an error of up to 200 calories per day.  Keep in mind this is before activity is factored in.  Now, factors that could result in errors of the added activity prediction include (but are not limited to):

  • genetics
  • hormones (such as issues with the thyroid)
  • fitness levels
  • heart rate (though some trackers do come with an optional heart rate monitor)
  • and even chemicals and pharmaceuticals (both prescribed and over the counter, such as thermogenics, nicotine, etc).  

All of these factors  could affect an individuals metabolism, and thus cause an error in the equation.

Then of course there is the most obvious issue:  is the fitness tracker accurately measuring your activity levels?  (see below)  Some of these trackers contain technology that will base caloric burn on even more variables, such as body temperate, sweat levels, and heart rate. But again, there will always be room for error based on individuality.

In short, no, chances are the calorie burn is NOT accurate.  It is likely within the ballpark, sure. But I personally wouldn’t plan my daily caloric consumption to a tee based upon my fitness trackers predicted output.

FitBit-Charge-pic-1

Con: Step Count Accuracy

In my experience, the step count of wearable fitness watches isn’t very accurate either.   I’ve been fortunate enough to be able to test and review a number of different brands of trackers.  I’ve noticed that each one has its positives and negatives when it comes to tracking distance and steps taken. 

While this post was brewing in my head, I decided to wear three separate trackers to the gym for the evening.  Yes, three.  I got a few funny looks, but hey, anything for science.   I intermittently checked the trackers throughout a slew of different cardio options.    Some trackers would register on the ellipticals, while others wouldn’t.  The same went for the stair stepper.   All three gave me different distance readings when running, none of which matched the treadmill. (Though in theory, the treadmill reading could have been incorrect as well.)  None of the trackers will register activity such as cycling, unless you wear the optional heart rate strap (only one of my trackers, the Polar Loop, offered that option.) At the end of a two hour workout followed by a 7 hour gym shift (where I walk a lot) each tracker varied from the other by a few thousand steps.

Now, not all hope is lost. Many of the available models allow you to set the sensitivity of the tracker to more accurately gauge footsteps. This is helpful, as some people are heavy runners/walkers, while others are very light.  Other wearable fitness tracker models will allow you to calibrate the length of your individual walking and running stride. This will also allow you to more accurately measure distance and steps covered.

Motivation.

A fantastic attribute of fitness trackers is the motivation they provide, both intrinsic and extrinsically.   Wanting to reach 10,000 steps a day (or another pre determined goal) can motivate an individual to get up and move a little or a lot) further than they might have otherwise .  Many of the trackers on the market today come with an online dashboard and often communities that can provide a world of external motivation.  For example, the Fitbit website not only awards your movement and activity with various “badges”, but invites you to challenge online friends to activity competitions. Examples include who can take the most steps over the weekend, or who can climb the most floors this month.

fitbit acheivements
Badges earned from Fitbit activity.

Final thoughts:

It may seem like this post focused on the negatives and inaccuracy of fitness trackers. But, my overall opinion as a fitness professional is that these devices can be an incredibly helpful tool for those who are wanting to either lose weight or simply become more active.  While the step, distance, and calorie count aren’t entirely accurate, they are still an accountability tool.  Accurate or not, there is no denying that fitness tracker readout of 15,000 steps shows you had a more active day than one that reads only 3,000 steps at the end of the day.

The key to success with these trackers is to remember that they are merely estimates. Your daily workouts and caloric intake shouldn’t be based exactly on these numbers.  Further, it is very important to note that these fitness trackers are simply a tool, and not a determination of your health. More importantly, they are not a determination of your self worth.  We all have days where we knock out 15,000 and beyond steps. Just as we all have days where the step count might not register past 3,000.   Rest days are important,  my friends.  If at any point you find yourself becoming obsessed with the numbers on the tracker, consider taking a break. And extreme cases, seek professional help from a counselor or doctor if necessary.

Fitness trackers have become synonymous with fitness and weight loss goals. Are they too good to be true? Let's analyze the pros and cons of wearable fitness trackers.

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Have you used a fitness or activity tracker?  Were your experiences positive or negative?  Would you recommend that tracker to others, and why?

Reader Interactions

Comments

  1. Great post Heather! I have a few trackers (Polar M400, FitBit One, Samsung GearFit, and JawBone UP24). When I go for a run using GPS none of the devices accurately reflect the distance I ran, and some were off by as much as 10%. If steps are off by 10% than you can bet the calorie estimates are also off by 10% or more. The part about them that I do like is the motivation to move more. the devices that automatically nudge me to get up if I sit too long are my favourites.

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  2. Gosh, differing by a few thousand steps is huge! I used my UP and now my VivoSmart mostly for the idle alarm – a reminder to MOVE every hour – rather than the total steps.

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  3. Very interesting! Crazy how the outputs were so differnt! I’m sure having a tracker would help me move more, but it is a lot to shell out for basically a glorified pedometer. I’m hoping to get a GPS/heart rate tracker soon though!

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    • That’s why I like the ones with a heart rate monitor, such as the Polar Loop. It detects increased activity due to heart rate, and adjusts caloric expenditure accordingly.

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      • I’m commenting here because my computer isn’t showing me any other place to leave comments 🙂

        I’ll be participating in a campaign with my local telephone service provider to test out the Fitbit Charge for a couple of weeks. I’m excited about it because, like you, I sit at my desk for several hours a day writing and researching and worry about whether or not the activity I get during the afternoon at the gym is truly enough to keep me healthy. I’ll let you know what I find out!

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  7. Great overview. I don’t often wear my Polar Loop anymore because it wasn’t giving me too much additional insight. Yes, I know my desk job keeps me stationary and I try to avoid sitting too long. Perhaps if my phone was upgraded and the Loop linked to it I would wear it more if only for the chime to get up and wiggle a bit reminder.

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  8. Such a great post Heather! I too have been testing out a couple of trackers and it’s been interesting. Like you, I was surprised by how little I did move during certain periods of the day. And agree that there’s no way that it’s 100% accurate but it helps you see the trends which I think is helpful. It’s definitely changed some of my habits!

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  12. I am now a convert of being a fitness tracker wearer. I think the positives outweigh the negatives and find that is helps someone be CONSCIOUS of how much they are moving besides not wearing anything at all.

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  13. I have the Jawbone Up and a Fit Bit. I wish they would automatically sync with my phone, I am so busy I sometimes forget to look at my stats. For me the fault is not in the device but in my own (admitted) accountability. This is a great review of your discoveries.

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  14. Great article. I really liked the Polar loop (and now M400) for being able to gage my sleep. I can often track my mood and cravings back to how well I slept the night before.

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  15. Even on machines I always put in my weight at 10-15 pounds under what I actually weigh and I go by those calories. So, if I am under estimating my calorie burn, I feel more comfortable with using those numbers.

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    • Honestly, out of the ones I’ve tested, I can’t say any is more accurate or effective than the rest. They each have their pros and cons, as mentioned some track certain activities better than others. I would base my decision (if you are looking to get one) on other factors that are important to you, such as community support, waterproof or not, heart rate monitor capabilities, etc.

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  17. I’ve been thinking about getting a fitness tracker lately, but your article offers some insight that makes me wonder if it’s the right thing for me. I definitely need more “up time” away from the computer, but am not sure if it would motivate. You mentioned that some have settings for lighter steppers – are there any models you might recommend that do? Also, do they have size adjustments or is it a one-size-fits-not-my-tiny-wrist kind of thing? Thanks for this great info Heather!

    Reply

    • Fitbit does offer various sizes (small and large) and has the settings for lighter steppers. Many other models, such as the Polar loop come with an adjustable band that you actually cut when you purchase it, to fit it to your wrist. Hope that helps! 🙂

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  18. I don’t think I’d ever want to wear one. It just seems like a lot of fluff and just another new tech object to stress people out about how “healthy” they are. I’m surprised by how unaccurate they are with the amount of steps though!

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    • It’s certainly not “fluff” for those who truly need an eye opener as to how much they do or do not move during the course of a day. Accuracy aside, there is no denying the difference between 2,000 steps a day and 15,000 steps a day.

      Reply

  20. I have been wanting a tracker for the exact reason you mention – as motivation to sit less all day long.I know that it won’t be perfectly accurate – but for me it is about the overall big picture that right now, even though I get in a run several days each week, still means I am sitting too much. I am waiting for the charge HR to come out in new colors and then hope to get it!

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  21. I don’t think I’ll ever buy a tracker, but I did have a widget on my phone I would use. I was surprised at how little steps I would get per day! Even if it’s not 100% accurate, I Was getting about 2-3K, so now I know I definitely need to be moving more!

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  24. I used this article for a worksheet I had to do in class. So thank you for writing this article because I really didnt feel like looking stuff up…

    Reply

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