Are You Burning as Many Calories as You Think?

Jennifer Purdie
by Jennifer Purdie
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Are You Burning as Many Calories as You Think?

Every morning you crush your treadmill session and revel in the total number of calories burned glowing on the screen. Sorry to damper your post-workout spirits, but that number is probably incorrect.


“Machines in gyms aren’t very accurate when it comes to calories burned, distance and other such metrics — they’re rough estimates at best,” says Brandon Mentore, a strength and conditioning coach from Philadelphia. “If two people weigh 200 pounds, but one is 5’3” and the other 6’1”, the amount of calories burned and the demand is vastly different.” This holds true even if the cardio equipment accounts for age and body weight.

Everyone has different metabolic rates as well. Mentore explains that athletes, for example, generally have a more efficient metabolisms that will actually burn fewer calories for the same effort and duration as someone with an average level of fitness.

The amount of calories you burn also depends on your lean tissue versus fat mass. “The leaner you are, the higher your metabolic rate and burn will be for the same effort and duration relative to someone who is less lean,” says Mentore.

In addition, the inaccuracy of caloric count could be related to the machine itself. Its age, calibration, elevation (for example, certain treadmill brands on a 0% grade are still not totally flat) and general maintenance upkeep all can keep it from displaying a more proper reading.

For those looking to lose or gain weight, these incorrect counts make it more challenging to try to gauge your daily caloric output. Most of us guess, but the odds of guessing correctly are slim to none.


Wearables employ accelerometer and altimeter technology to detect your steps throughout a day — whether you are working out, or you’re simply walking from your car to work. Some trackers can even detect power output, making for super accurate results of your activity level.

When it comes to calorie counting, wearable fitness gear has given the user the ability to track calories instantly, rather than rely on memory, providing better results and more reliable data,” says Junior Leoso, a personal trainer from San Diego. “It’s provided an entirely different aspect to training, as it’s given data to a world of people who typically only care about the end result.”

Wearables also come with other benefits to entice you to spike your movement levels. “[They] can give you reminders when you haven’t been active in a while, as well as keep track of your data, enabling you to do weekly and monthly outlooks on calories burned and overall activity level,” says Mentore.

These devices aren’t limited to a younger, more technologically-savvy generation either. According to Rock Health, the first venture fund dedicated to digital health, no demographic variables had any significant effect on digital health. Seniors and millennials are equally as likely to use wearables.

The market for this technology is astoundingly healthy. Statistica, a statistics portal for market data, says wearables are expected to reach a value of $19 billion in 2018, more than 10 times its value in 2013. In addition, 27% of consumers expect to purchase a wearable fitness device within the next 12 months (2016 data).

The behavior toward fitness technology has shifted. It’s no longer viewed as a passing trend, but something that’s here to stay. It’s empowered people to improve their lifestyle behaviors in unparalleled fashion — from walking more to monitoring sleep to lowering heart rates. The impactful data created by wearables appears to motivate people to take charge and produce positive changes, making them worth their cost.

We are lucky to live in an age when technology can help solve challenges. Expect wearable fitness to continue to make individuals healthier for decades to come.

About the Author

Jennifer Purdie
Jennifer Purdie
Jennifer is a Southern California-based freelance writer who covers topics such as health, fitness, lifestyle and travel for both national and regional publications. She runs marathons across the world and is an Ironman finisher. She is also a certified personal trainer through the National Academy of Sports Medicine. You can follow her on Twitter @jenpurdie.

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21 responses to “Are You Burning as Many Calories as You Think?”

  1. Avatar wackawacka says:

    Wearables like Fitbit are useless. They still vastly overestimate. The only thing that’s close to accurate is a HRM around your chest.

    • Avatar Brad Vickrey says:

      I had a Garmin Vivoactive HR that was wildly inaccurate with it’s overestimation. I spoke to Garmin about this several times. After a few calls, the rep basically told me that they had upgraded the product and they sent me a new one. The new version seems to be very accurate. If anything, it might be lowballing me now. :^)

    • Avatar Timothy Fish says:

      The number of beats per minute of your heart cannot tell you how many calories you are burning.

      • Avatar wackawacka says:

        Yeah, forget science. It’s magic!

      • Avatar Xanth says:

        It’s not about getting an “accurate” reading. It’s about getting a somewhat close estimate. Just because it’s not accurate down to the calorie, doesn’t mean you can’t use the information provided as a progress indicator for yourself. 🙂

        And in actuality, you can use your heart rate to further increase the accuracy of such things. Remember, the more information you’re dealing with, the closer to reality you get.

  2. Avatar Zack says:

    The author did a good job showing how all the machines can be inaccurate but doesn’t explain how a wearable is any more accurate then they are. How does that science work? how is an accelerometer any more accurate, please elaborate. Much like the machines that are wildly inaccurate, does the wearable assume you take the same size step every time? I doubt any ones stride is the same all the time… again… write the science, don’t tell us they are great because everyone is buying one. Tell us why we should think they are more reliable. Don’t throw one sentence in about detecting power but not how they can. I’ve debated spending the money on one for a long time but other then “they are great”, not many impartial sources can describe how or why I should spend the money to only count my steps.

    • Avatar DaBoss says:

      Lighten up Zack. Nobody is forcing you to do anything. Jennifer has presented a perspective for us to consider. If you want to know more about how wearables work then go and look it up!

  3. Avatar luluhoo says:

    I’ve read about this, and I’m convinced that heart rate is the best way to gauge calories burned. You can find charts that give calories burned by heart rate and weight. It’s really easy to gauge your heart rate by taking it manually for 6 seconds. (multiply by 10)

    • Avatar Richard Schmier says:

      I don’t buy that for a second. I can ride a bike for an hour with my heart rate at 140-150 but I can only run for a few minutes with my heart rate at 140-150. Am I really only burning the sane amount of calories? What if I’m doing heavy squats and my heart rate is 140-150? Are you really saying I burn the same amount of calories jogging as I do lifting 300 pounds plus my body weight?

      Heart rate monitoring can only tell you how many calories your heart is burning combined with some loosely calculated assumption about what the rest of your body is burning.

      I think the only truly accurate way to measure calories burned at any given moment is to be measuring everything. Heart rate, O2, CO2 expenditure, blood sugar levels, body temperature of the entire body, internal and external, then combine that with known energy calculations such as how much force is required to move X weight Y distance, etc.

      But of course that is all far too complicated to actually pull off unless you are in a very expensive laboratory setting.

      Our I could just be making most of that up as I wrote the comment. Sounded pretty good though huh?

  4. Avatar jackruston says:

    Even with a chest strap you need to know minimum/maximum/VO2max etc to get a reasonable accuracy. So are all these things useless? No – but you do need to factor in some inaccuracy, and then go by trial and error over a period of time. If you have particular workouts that you’re doing regularly you tend to get a feel for whether it’s over, under or about right. At the end of the day it doesn’t matter if it’s not exact, as long as you’re getting the result you want. Personally I use a blue tooth chest strap with an app, but I don’t treat it as gospel, although I do now have a pretty good idea of my numbers – its main role is to allow me to gauge effort, intensity on a session.

  5. Avatar Dave Gee says:

    Track your weight with some like the Libra App – your average weight trend is the figure that really matters in the end as far as working out your calories in vs calories out differential.
    Presuming you have some sort of fairly routine exercise and diet regime, you can then adjust it to suit – more exercise/less food if weight if the graph is pointing higher than you want and the opposite for lower.

  6. Avatar Tim Green says:

    I agree that gym equipment cannot be relied upon to measure calories accurately. Distance is a reasonable way of estimating burn, but distance will only be accurate if a route is recorded, either by GPS or by manually entering the route. A treadmill’s reported distance is not at all reliable.

    However, “wearables” are not a magic bullet, either. They are not all created equal, and both hardware and software can make a huge difference to their accuracy and usefulness. If you’re not measuring HR, you’re not going to get an accurate read on calories burned on a treadmill, regardless of anything else. HR is better than distance, even when running outdoors: I’m an inefficient runner, so wearing an HRM increases my reported burn per mile by around 10% compared to GPS-only sessions.

    Many wearables are nothing more than glorified step counters. If you regularly work out, steps are a next-to-useless indicator, and a step counter cannot measure swimming, cycling or resistance training. Duration and intensity of exercise will have a far greater effect on your health and fitness than the number of steps you take.

  7. Avatar Dennis Meyer says:

    Goodness, give the girl a break. What a bunch of grinches and sourpuss’ you are. Did someone poop in your oatmeal. None of these metrics are intended to be, or are capable of being, exact sciences. What they do do (sorry for so much poop talk) is they add a dose of motivational fun to the equation that does get a lot of fat asses off the couch and on the pavement, like me. I am a contractor who is OCD when it comes to accuracy and details but I don’t care if my gadget says I burned 285 calories or 340 calories, what I care about is that I got out and exercised and that the scale will read a little less tomorrow than it did today. My wife’s and my Fitbits track our walks accurately to the foot. Out of curiosity I counted a 100 steps last night and it logged 105. Heck, that’s close enough for me. I say give all the geek gear a break, manage your expectations, and enjoy the emotional and physical benefits of burning calories, regardless if it is off by 10 or 20%. A 70 year old whose only bucket list item is to Get Fit, again.

  8. Avatar Timothy Fish says:

    I trust my Garmin Edge about as much as I trust anything, because it can get a power reading. I don’t, however, trust gym equipment. With wearable, wattage should be calculable based on GPS and altitude, but if it doesn’t know what activity you are doing at the time then the calculation will be off. For example, a wearable unit can’t tell the difference between climbing stairs and riding an escalator, but they both show the same elevation gain in about the same amount of time.

  9. Avatar marisa says:

    Is there a wearable fitness tracker/accurate calorie burner for wheelchair-users yet?

    • Avatar Chris says:

      Ah yes, this was exactly my thought. I use a chair, and I just use my phone-which goes in my pocket. Google fit sometimes registers it as a bike ride, and sometimes it doesn’t measure it at all. I think people forget that those in chairs can get good workouts in as well, but we have no way to measure. So, what i do is I just set my stopwatch function on my phone when I take my chair on a trail (it’s blacktop), and just plug in when I’m done. I know it over estimates, but keeping that in mind, it still helps me figure out my cardio for the day. Either way, it’s over the 30 minutes, and it’s still quite a workout to push a chair on a trail that isn’t perfectly straight.

    • Avatar Victoria Wheeler says:

      Google: fitness tracker wheelchair

      You’ll get several responses, including Apple’s watch & the Fitbit Flex.

  10. Avatar Mick says:

    What do you think about the calorie count reading on MyFitnessPro vs NikeRunClub app. They’re both measuring my steps and distance (and I believe both have my height/weight) but are wildly different. Nike app often gives me numbers 2 x’s (or higher) cal readings than MyFitness. Though more conservative, MyFitness seems more accurate.

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