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Fitbit Overestimating Calories Burned

My BMR (using several different calculators) is about 1372.   On a day when I get about 10,000 steps through normal activity (i.e. NOT exercising, just walking around work and doing stuff), fitbit tells me I'm going about 4.5-5 miles.   That should add no more than 500 calories to my total (probably closer to 400 or 450).  Again, I haven't done any additional exercise, but fitbit somehow calculates my daily calorie burn at over 2100.    This makes the app totally unreliable for managing weight!    It's showing huge calorie deficits (and I give myself a big margin of error on calories going in) but my weight is stagnant.  

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Calories in are an estimate - calories out are an estimate.  The data provides a basline.  If you're not progressing, either reduce calories in or calories burnt.


Even is the data is inaccurate CICO is not, and using the data you can customize for the desired results.


How long have you been on your plan and how long has the weight been stagnant?


I advise to make changes after 2 weeks stagnant (for men) and one month (for women).  Have you plateaued for over a month?

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Yes, I understand it's all an estimate, but I think overestimating by 400 calories is too much.    The BMR is known, and Fitbit should have an accurate number for that (though, annoyingly, fitbit doesn't show that number anywhere in my profile) because my height, age, weight numbers are all fine.      And yes, platueau is over a month.  


I know what I need to do--not rely on fitbit when estimating calories out.   My goal is a 400-500 calorie per day deficit.   If fitbit's CO "estimate" is off by that much it means my CICO has basically been even, therefore no weight going anywhere.  

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BMR can vary between individuals, as will the calories burnt.  Walking into the wind, uphill, with extra clothes on will all increase the calories burnt.  Conversely, inverse conditions can lower that burn.  Fitbit can't tell most of that.  Sorry, but none of this is an exact science, nor are the labels for calories on food or how we process them 100% either.


You have to gauge the real world results with the data and make changes to adapt your plan.  I am not aware of any wearable device that provides 100% accurate info.  Most of us start by overestimate burn and underestimate calories ingested, and all the apps, technology and devices we use can lower that margin, but it will never be 100% linear or predictable.


Hope this helps and you're not too discouraged.  It is a real grind to lose weight!

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 Before you stomp your fitbit into the ground in frustration, I'd like you to get a tape measure - or find an area that you can walk a straight line for 10 strides, walking normally. Measure that distance and divide by 10 to get your stride length. 


It could be that your stride is shorter or longer than the default value. I think if you adjust that, the steps you take should be more accurate and as a result, your caloric burn as well. 


5 miles, if walking normally would take most about 12 minutes per mile, or an hour. Possibly more if you have a short stride. (also depends on how briskly you're walking)


At rest - in my case - I burn about 6 calories a minute. When walking, I burn about 11 per minute. If I walk for an hour, it's an extra 300, at least. Fitbit generally over-credits me with about 400-500, too. 


The OCD in me internally screams about this lack of accuracy, but I just disregard it and go with the 1000 calorie deficit model and if I only had a deficit of 500, I'm good with that. I'm even good with no deficit - I just don't want surplus. It's not a race for me. Slow and steady wins this.


So - I would revisit the stride measurement (under settings on your dashboard) and see how far off it is (it may be spot on, who knows?). 
Then, I would also start logging your fluid intake. I've noticed if I don't consume at least 60 ounces of water a day, I don't lose weight. I can't seem to get in more than 80 ounces if I don't exercise and get sweaty. The fluid intake - if you attempt to take in the same amount each day - will help you determine if the weight lost or gained is liquid or simply intestinal gut. 


Additionally, logging your food is like keeping your checking account in good order. You see how much is going in as well as how much more you can have. And - on days where the results on the scale are favorable - you can look back and repeat the process - eat the same foods at about the same times and drink the same amount of water and get about the same steps - the next day's results will be favorable as well. 

Those who have no idea what they are doing genuinely have no idea that they don't know what they're doing. - John Cleese
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I posted this back in February in the help forums... Here's a link if you want to read the entire thread.


First, I'm going to start with the premise that the Charge HR is calculating calories burned based on a combination of height/weight and activity levels, including time spent in the various heart rate zones (Fat Burning, Cardio & Peak) and that people might want to use this data to aid in their weight loss plans.


So based on the 220 minus age formula that Fitbit uses, that puts my maximum HR at 180.  And looking at the default HR zones -- Fat Burn 90-126, Cardio 126-153, and Peak 153+ -- it looks like they're using 50% for Fat Burn, 70% for Cardio, and 85% for Peak.


Now you look at other sites that speak to tailoring your target zones based on your own health factors, taking into account your resting heart rate, and you get much different results, not to mention they generally use 60% as the minimum threshold for Fat Burning.


Look at how Polar calculates it.  Basic age formula from above, but they use 60%, 70% and 80% for their zone limits.  So using their age formula, my zones would be 108 for Fat Burn, 126 for Cardio, and 144 for Peak.


Now their formula for factoring in your resting HR.  Side note... my Charge HR says my resting HR is 85, but looking at the graphs at the point in time this measurement should come from it's actually in the 68-70 range.  Let's call it 70.  So basically, take your max HR and subtract your resting HR (180 - 70 = 110), then multiply by the percentage for each zone (60%, 70%, and 80%), and add that number to your resting HR (70).  So this would put my Fat Burn zone starting at 136, Cardio at 147, and Peak at 158.


Now look at  Again, same basic age formula from above, but they use 60%, 75% and 85% for their zone thresholds.  So age based limits would be 108 for Fat Burn, 135 for Cardio, and 153 for Peak.


For their health based formula, they also use the max HR minus the resting HR... they call this a heart rate reserve, which we previously established for me is 110.  And their method is the same as Polar's, the only difference being the different percentages for each zone.  So again, 136 for Fat Burn, 152 for Cardio, and 163 for Peak.


To put all this into a slightly easier to read format:



Fitbit: 90 (Fat), 126 (Cardio), 153 (Peak)

Polar: 108 (Fat), 126 (Cardio), 144 (Peak)

Active: 108 (Fat), 135 (Cardio), 153 (Peak)



Fitbit: N/A

Polar: 136 (Fat), 147 (Cardio), 158 (Peak)

Active: 136 (Fat), 152 (Cardio), 163 (Peak)


Huge differences here, particularly regarding Fat Burning, and here's why it should be looked at a bit closer.  Say for instance that someone strictly using Fitbit's recommended/default settings spends the majority of their time aiming to stay in the Fat Burn zone.  Based on the comparisons above (and I'm more inclined to trust Polar's zones... they're known for their HR monitors), if you stay within Fitbit's Fat Burning zone, you haven't even reached the Fat Burning zone identified by the others.  And by the same token, someone staying within the lower-to-middle limits of Fitbit's Cardio zone again, haven't even reached the Cardio zone identified by the others.


I can easily see that someone following solely along with the data from their Fitbit (calories burned, perceived activity levels, HR zones, calories left to consume, etc.) might be sorely disappointed... or simply left wondering why they're not losing any weight, even if they're strictly following what their tracker tells them.


Anyway, sorry for the long read (if you're still here)... just dug a little deeper into it all today and thought I'd share what I came up with.

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I'm not sure you know what the BMR is, it is the number of calories you theoretically burn if all you did was lie on the bed all day and didn't nothing but breathe from midnight to midnight. 


No getting up to go to the bathroom, or eating, or even watching TV.  Just lying there, completely still for 24 hours.


The moment you get out of bed your body is burning more calories.  My BMR is down to 2050, and the other day due to a strained calf muscle, I was home resting the whole day.  I did next to nothing, and I burned 2200 calories.  A new LOW for me. 


So if your BMR is 1372, and your think you exercised 400-450 calories, that's around 1800.  Another 300 calories just doing your daily stuff, that's a very realistic amount of calories doing normal day to day stuff.  So I don't think your Fitbit is that wrong per se...  But....


There there is another issue that your fitbit can't detect.  Your BODY wants to go back to what you used to weight. It's like having energy reserves, and want's those reserevers back deperately.  It lowers your hormones to make you more hungry, and then it lowers your metabolism to burn fewer calories  Your BMR might actually be 800 or 900 because your body is fighting you to gain weight.  Unforutately, short of complicated blood tests, and other test equipment, there is no way to know when this happens.  But a clear sign is when you stop losing weight, and should be losing more.


And the more weight your lose, the more your body lowers your metabolism to try to find any way to get the weight back that you have work so hard to lose. 


They only way to defeat this is lower your calories, or increase your activity, or both. I was stuck at 230...  Then I got stuck at 223...  Still there right now, but that's mostly because I can exercise right now due to a injury.  I've got another week or so before I can start to exercise again.  And even then I have to start off slow.... 

John | Texas,USA | Surge | Aria | Blaze | Windows | iPhone | Always consult with a doctor regarding all medical issues. Keep active!!!
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Try calculating your TDEE through an online calculator so you have a baseline for how much you burn and for now ignore what fitbit says you burn. If you exercise, use the activity tracker that relies on HR to see what you burned. Use the app to log all your calories in and mentally compare it to your TDEE You are stuck because you are probably eating to whatever your TDEE is. You would gain if you ate over and lose if you ate under. I know its all what you already know, but I would try manual for a time and see the scale move.

Elena | Pennsylvania

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To follow up on what @JohnRi and @emili have said regarding TDEE and BMR, I'll show you what sedentary (non-exercise) TDEE looks like for me. Sorry this is a little numbers intense but this is a numbers topic:


I've only had a fitbit for about a month. Prior to that I used another app to track my calories in/ calories out. That app uses a sedentary multiplier to estimate TDEE based on BMR. They use a factor of 1.45, so TDEE = BMR * 1.45. Any exercise you do beyond that is considered extra. Many people consider this high for sedentary but fail to realize that sitting at a desk and working burns more calories (1.5 METs) than sitting and watching TV (1.0 METs)


I'm a sedentary office worker that (before I got my fitbit) didn't move around that much outside of running and weight lifting. I lost weight using that app and maintained my weight for several years based on a TDEE estimate of:


TDEE = BMR * 1.45 + Exercise


In other words, I assumed my TDEE started at BMR * 1.45 and any exercise was additional calories toward my TDEE.


Without exercise and without intentionally walking around, I get about 5500 steps on a non-exercise day. So, for me, 5500 steps seems to equate to about BMR * 1.45.


In your case, at 10,000 steps you get an estimated TDEE of 2100. That's a multiplier of 1.53 without exercise. This doesn't seem that far off in terms of a TDEE estimate.

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Hi guys, first-timer here. I'm pretty much in the same boat as the OP. I've been concerned since I got my charge HR that the BMR and calorie allowance both on personalised and sedentary settings are too high.


My BMR is calculated on Fitbit as being 1901cal, vs 1905 on MyFitnessPal and 2019 on Nutracheck - so pretty consistent on that basis. 


In terms of assumptions on my daily basic activity however;


MyFitnessPal: 520

Nutracheck: 808 

Fitbit: 3250 (Avg calories burned on a typical sedentary day for me) less 1901 (BMR) = 1256


That's a pretty hefty range there.


What's concerned me is I've experienced success with Nutracheck in the past, and from memory at that time/age/weight my target was approx 1500 cal a day to lose 2lb a week. I've had that stuck in my head since. If I did exercise, I'd win a bit more leeway on that particular day.


Bearing this in mind, after a week of personalised tracking with Fitbit and no change in weight (I wasn't overly shocked as, playing by the Fitbit rules, I didn't feel as if I was doing any more or eating any less) I changed to Sedentary and started using MyFitnessPal to log food (bit easier). 


Yet again however, no change. And if I look at my calories consumed, we're talking roughly on average 2000 eaten and over 3250 burned. I should be seeing some impact if those ratios are correct, however as I said - zilch.


As a bit of kit I love it, great technology and it's given insight about myself I didn't think I'd get - but - I clearly have to do some calibration work because at the moment were I to follow its guidance i'd stay 14st 4lbs forever!

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Are you using the fitbit Charge HR? or just one that counts steps?

I found that my Charge HR was more accurate than other online calculators.  I was using a calculator online that was estimating my calorie burn.  I plateaued after a while because my body adapted and I was a lot healthier than I started out.  My body wasn't having to work as hard so it wasn't burning as many calories as before. 


After purchasing the Charge HR. I saw that by it, I wasn't burning as many calories for certain workouts.  It showed me to be burning at least 200-300 less calories for certain workouts than what the calculator was.  


The problem with the estimation calculators is that it can only give you these estimations by your age, weight, gender, etc.  It can't tell how much muscle you have or your stamina or how good of shape you are actually in. 

This is why people who are out of shape and overweight generally have a decent amount of sucess in the beginning.  Their body is shocked in the beginning and they will see a drop on the scale.  As the body adapts tho, it will start to level out and the person will have to continue to work harder and change up their routine.  

You have to find balance.  You also have to find non scale goals.  When you only focus on the scale you tend to lose focus on the big picture.  

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Yep, got a Fitbit Charge HR. 


As for the rest, my weight is around the highest it's been. In the past, as you describe, it's fallen away quite quickly at the start - which is actually why it's a concern for me that so far there's been zero impact of using the fitbit in conjunction with food logging.


Reality is, compared to the past, my daily intake allowance seems just too high. I'm an adult male, 6ft, work an office job and play football twice a week for an hour a time. If I'm wanting to lose 2lb a week, then eating 2000+ cal on a "normal" day of 8-9000 steps is just too high. That's based on my own experience of losing weight in the past.


The Fitbit seems good at logging steps and heart rate, but the software is over-estimating the calorific impact that has for me.

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@Fitzchiv wrote:


I'm an adult male, 6ft, work an office job and play football twice a week for an hour a time. If I'm wanting to lose 2lb a week, then eating 2000+ cal on a "normal" day of 8-9000 steps is just too high.

I think these numbers are within range of common TDEE estimates. If your BMR is 1900, then you'd need an activity multiplier of 1.57 to get to 3000 calories of TDEE which would allow you to lose 2 lbs per week eating 2000 calories per day. A 1.57 activity multiplier doesn't sound that far off if you get 9000 steps per day and play football 2 hours per week.

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Begs the question then, why aren't I?! ;-)


I'll give it another couple of weeks and keep tinkering, ultimately this is my responsibility not the bit of kit on my wrists. Just need to work out how best to use it.

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The truth is even with the heart rate monitor giving it another way of making things a bit more precise, this is still based on a scale.  You may carry less fat that some.  You may carry more muscles.  I have learned that everyone is different.  One thing that helped me is changing things up a little.  If you are documenting everything and know exactly what you are eating...then try adjusting your calories by 200 each day.  See if this helps.  For some this may seem like a lot...for others it's the equivalent to a light snack.  Also try exercising at different times of the day or using the part of the app that shows how active you are all day.  I like to try and have each of the hours show that I was active.   I don't always meet this...but I try.  It just pushes you to raise your heartrate more often during the day.  I work in an office and this can be hard...but just standing up and stretching or making a lap around the office can do that.  I find reasons to make extra trips or stand to do tasks that you would normally sit for. 


Good luck.  I know it's frustrating...but you are doing something and not just giving up. It's all a balancing act and everyone's center is different.  The hardest part is finding it. 

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I have the very same thing; this way the Fitbit is totally useless to measure activity vs calory intake.

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@Evelyn__020: can you be more specific as to why your Fitbit is totally useless, and how you know better (about your activity level and your corresponding energy expenditure)?

Dominique | Finland

Ionic/Versa, Aria, Flyer, TrendWeight | Windows 7, OS X 10.13.5 | Motorola Moto G5 (Android 7.0), iPad Air (iOS 11.4.1)

Take a look at the Fitbit help site for further assistance and information.

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Guys -- not to be an insensitive curmudgeon, but it seems to me that the whole "Fitbit overestimates my calorie burn" complaint is often made by those who have no basis or data to back it up.


They have not measured their metabolism in a calorimetry chamber, nor have they carefully tracked their Calories In and Calories Out and correlated it against their actual changes in weight.  Yet, they have somehow concluded that Fitbit is so inaccurate as to be useless.  Based on what?  Their intuitive guess as to what their calorie burn should be is somehow more trustworthy than Fitbit's heart-rate based estimates?


In my case, I have 99 days of data to find that Fitbit underestimates my daily calorie burn by about 160 calories.  In spite of the inaccuracy, I am able use it as a very effective tool to help me lose weight.  If it overestimated my calorie burn, it wouldn't matter.  I'd just adjust accordingly, and use it as a tool to help me lose weight.


Gently:  there is the device on our wrist and the image in our mirror - which one is responsible for our outcomes?   This is a golden opportunity to stop blaming outside factors for our own lack of results.  100% of all measurements made in the physical world are subject to error (food calorie estimates, calorie burn measurements, and scale weights).  To be surprised and flummoxed by something that is 100% to be expected is less than adaptive.  OK, I'm done with the lecture.  Smiley Happy

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How eloquently put, @Daves_Not_Here! I think people who dismiss their Fitbits as useless because they’re inaccurate should look at this recent post by @EmjayH: she was able to determine her Charge 2 overestimated calories burned by 10%, yet this didn’t prevent her from using it to her advantage (and with what results!).

Dominique | Finland

Ionic/Versa, Aria, Flyer, TrendWeight | Windows 7, OS X 10.13.5 | Motorola Moto G5 (Android 7.0), iPad Air (iOS 11.4.1)

Take a look at the Fitbit help site for further assistance and information.

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It's a good thing you're done with the lecture, as you call it. Just
because data may not be shared with you, does not mean it's not there. In
similar mode you assume that people who notice an overestimation are not
achieving results. Both wrong in my case, at least.

Let's get back to a more constructive dialogue: are there tips how to
adsjust the measurements for the Charge HR so it reflects better the actual
energy use? If you do indeed have data that provides a standard, perhaps
the Fitbit can be tweaked to produce the same measurements?
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