Charge 2 calories burned too high

[LisannevdL]

I just got my new Charge 2 on saturday so I've not tested it very long, but the calorie count on it seems WAY off. The BMR on it seems correct for my height/weight (1555) but then the calories burned when simply walking a bit are way too high.

Saturday, I went shopping for a few hours that got me around 10k steps in total. I also did a kickboxing workout (268 cals) and went biking (219 cals) and Fitbit calculated 3000 (!!!) calories burned that day. That just can't be right, when my BMR is only 1555 I should've burned 1445 cals with exercise according to Fitbit. Subtract the kickboxing and biking (which is way higher intensity than the walking, calories for that seem correct) from that and that leaves 958 calories burned for walking +/- 10.000 steps.

Has anyone else had this problem? I've Googled for a bit and it seems it was a problem back when the first Charge HR was released too, but I couldn't find a solution. I love the Fitbit and the app but it seems when it takes the constant HR into account when you're not very fit it just overestimates by a WAY too high number. If I ate what Fitbit is telling me I can eat, I'd gain an incredible amount of weight in a very short time.

The numbers I got when I was just counting steps without heart rate (using my phone, before I got my Fitibit) was way closer to the actual number I should be getting for something as easy-going as walking while shopping.

Moderator edit: format

[MrsBonnick]

Hi! i got my Charge 2 a few days ago and started wearing it last evening and today. how's the tracking going for you these days? is it better now? coz even for a new user like me i also was perplexed how did i burn 1000 over calories by sleeping alone?? and also when i woke up it states that ive walked 41 steps. how is it possible to have steps recorded when you're asleep?? does that happen to you as well.? 

[FarOut]

Steps is most likely caused by you having the wrong hand selected in settings. Also each morning you should wake up with calories burned for doing "nothing." It's the energy used by your body to repair and otherwise keep your organs and cells working. For example if I just laid in bed and never left for 24 hours I would still burn 1700 calories just for existing. 

[Cortic]

Here is some data I have collected over the past 12 weeks since wearing my Charge 2 from the start of January, to showcase its inaccuracy in calories burnt. I am meticulous with my tracking so I an quite confident this data is accurate. All numbers presented are weekly averages.

Week 1 - Burnt 2967 - Ate 2380 - Bodyweight 66.2

Week 2 - Burnt 2675 - Ate 2423 - Bodyweight 65.6

Week 3 - Burnt 2422 - Ate 2544 - Bodyweight 65.5

Week 4 - Burnt 2733 - Ate 2605 - Bodyweight 66.0

Week 5 - Burnt 2767 - Ate 2560 - Bodyweight 66.6

Week 6 - Burnt 2749 - Ate 2505 - Bodyweight 66.5

Week 7 - Burnt 2899 - Ate 2643 - Bodyweight 66.9

Week 8 - Burnt 2777 - Ate 2697 - Bodyweight 66.7

Week 9 - Burnt 2902 - Ate 2698 - Bodyweight 67.0

Week 10 - Burnt 2917 - Ate 2606 - Bodyweight 67.2

Week 11 - Burnt 2818 - Ate 2605 - Bodyweight 67.8

Week 12 - Burnt 2901 - Ate 3040 - Bodyweight 68.0

In every example except the last, I have burnt well over what was consumed and steadily gained weight.The law of thermodynamics says this cannot be so, and therefore, lies an issue with the FitBit and its ability to track daily calories burnt. None of this was logged through selecting "activities" on the fitbit, just wearing it 24/7.

[Shka]

Brilliant post, Cortic. Your data over the course of 3 weeks suggests you consumed ca. 13 000 calories more than you burnt (that is nearly 2 kg of body fat in case you gained just fat and didn't lose or gained any lean mass or are holding onto water) despite eating less calories than what fitbit measured you burnt. 

Despite this inaccuracy, i  think fitbit is an activity tracker that motivates us to move more during the day and not an accurate sports watch. Even those differ in measurements. 

[SunsetRunner]

Cortic,

Thank you for taking the time to post this! Did you use the Heart Rate function when getting the calories burned? Have you tried turning it off and doing this experiment?

[Cortic]

Yes, the Heart Rate function was enabled. I could track again without enabling it, however, that would also mean I would have to manually log my physical activity which could be a pain as otherwise it would just assume I would be doing nothing but walking around.

[gojensen]

We need to be able to trust this thing... I see from my activity report that the activities I did counted as steps as well (i.e. 40 minutes of martial arts gave me +2000 steps and +420 kcalories burned)... could it be as simple as that the app counts those steps in addition to the calories and thereby "skewing" the numbers?

My total today is 3359 kcals burned with ~9000 steps and 50 minutes of workout tracked. There's no way I'm eating 3359 kcals to maintain my weight - I'd way 300lbs next month if I did that...

Has fitbit weighed in on this?

[SunsetRunner]

I have contacted fitbit before and received no resolution.
I have found that not turning on the hr monitor and not logging in activities, still gives a somewhat (?) accurate count, confirmed by me not gaining weight.

[gojensen]

For what it's worth... while I sometimes think I get wildly overestimated kcals from Fitbit, yesterday was a day "off" for me... and it estimated 2300kcals... which is just about my BMR. 

On my ACTIVE days though it seems to overestimate... maybe it's just messing up steps, activity and BMR... fortunately for me I've been doing this for so long that I have a pretty good idea on what my activities should burn (from mostly using a proper heart rate band previously) that I can cope.

[Oregonsunray]

Wow, thanks for kicking up this discussion!!

I just upgraded from Alta to Charge 2 and was trying to figure out what's going on with my calorie burn.  I've only worn it two days, but it's obviously counting too high. If I ate that, I would for sure gain weight (experienced user of Fitbit/Garmin/MyFitnessPal). 

Really bummed since watching HR - resting, at work, exercising - was my whole reason for upgrading.

Does turning it off stop nighttime tracking too?  I don't want to turn it on at night, turn it off in the am, AND manually enable workouts with the button!

Much to my dismay, my higher "sitting" heart rate (from stress, caffeine, whatever) is not burning calories that Fitbit thinks it is.

For the record, HR seems accurate.

[Oregonsunray]

liseannevdL - are you still using it and with what settings?

[Laura10]

I have changed my maximum heart rate using a different formula which gives me a higher number. I've been taking Orangetheory classes, and I notice where my heart rate is when I first hit the "orange zone." With calculations I determined they have my MHR at 178, whereas the standard 22 - age would have me at 168. Raising this manually in the Fitbit app has brought down the higher daily calorie burn to a more reasonable number. Although I do think that the calories calculated for my workouts are lower than they should be. Often the Orangetheory class show I burn about 70 more calories for the hour workout than my Charge 2 shows.

Overall, I am not too concerned with the exact numbers. I know from past weight loss success about how much to eat to lose weight. I try to just aim for that number even if the Fitbit app shows I am under in calories. I like the heart rate feature more for the resting heart rate data in the morning. I used to use a Jawbone Up for this, but it broke, so I got the Charge 2 (and also now an Alta HR) for that purpose.

[Oregonsunray]

Thanks! I messaged Fitbit bc I'm disappointed with the huge jump in calorie burn after upgrading my Fitbit, and annoyed I need to work around it. Will share if they offer any useful info. Best wishes

[Chaps]

Although I do agree the calorie account is a bit high, I think it is closer than many are giving it credit for.  There are several things to consider.

First, the HRM on this is a wrist based monitor, and therefore not as accurate as a chest monitor, it can be off by around 15% at any given time, and when more active, it is more likely to be off.  A higher HR reading will fool it onto thinking you have burned more calories than you actually have.

Second, the OP had mentioned her BMR, then added her two workouts and subtracted that number from the difference of her fitbit and her BMR, resulting in roughly 1000 calories burned by walking.  It isn't quite as simple as that however.  BMR is the calories burned just to survive, it accounts for cardio, pulmonary, central nervous, sexual, and skin functions at a resting state (non digestive).  Just eating will increase your calories burned as you digest, additionally, the 200+ calories she burned for each workout were not the total calories burned as a result of said workout.  Your body doesn't stop burning calories when the workout ends.  You will continue to burn additional calories as your body recovers from the workout.  

All that said, even accounting for the wrist based HRM discrepancy, I do believe these read higher than is reasonably accurate, and hopefully they will correct this in a future firmware update.

[KyzMarie]

I have a charge 2 also.  2 weeks now and I'm still trying to figure it out.  According to mine I'm some kind of superhero.  I've burnt something like 9,000 calories today and it's only 1.30pm.  I'm pretty sure I should be dead if that was the case.

No idea how to fix this?

[lb80]

If anyone's interested in a technical read on exercise and calorie expenditure I found this article interesting and helpful.  Basically explains that calories burnt is not directly related to HR but instead the body's consumption of oxygen and depending on what type of exercise you do (even at the same HR) the calories burned can be different (due to different oxygen consumption required).

I believe that any extra calories FitBit is including in our estimates could be due to inaccurate step counts. Walking uses your leg muscles (the largest in the body) and consume the most oxygen and limit blood flow the least. If you're moving your arms and registering steps, which does happen to me specifically when I'm cleaning dishes after dinner, FitBit is most likely assuming you're walking and thus burning more calories then you actually are. A high HR without steps should indicate upperbody exercise vs. with steps which should be a lowerbody exercise.

Ultimately this is just an estimated calorie burn and we all need to learn how to use it for our body's particulars and regular activities ... unless of course you're up for wearing an oxygen mask all day to monitor your O2 consumption! 🙂

[gojensen]

Uhm yea we can't trust this thing... today it wanted me to eat 3800kcal... do you know what would happen to me and my body if I did such a stupid thing???

[AdriK]

Yep. I find it to be incredibly accurate. 

Remember, the more information you give the device, the better it works. If you wear it all the time for a few days, it becomes even more accurate. 

Don't lie to the thing about your height and weight (a lot of people do), set your dominant hand, etc.... Feed your Charge 2 accurate info and it will return the favor! 

❤️

[temazur]

Just got mine yesterday.  After I set it up I did a short run on the treadmill (which is an old, broke down treadmill that tells me nothing on output, so no luck there of comparing a heart monitor).  20 minutes, said my average heart rate for it was 152 BPM (seems legit, I've never used anything with a heart rate monitor before).  But then it said I burned 278 calories in the run.  

No way did I burn that many calories running that short amount of time.  

I'm going to keep an eye on the calories burned through exercise sessions to see how off they are.  I usually discounted the exercise fitbit fed over to MFP, but now I need to know if I have to adjust my own calculation on that.

[Mukluk4]

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@Cortic wrote:

Just as an update, with the HR function turned off, my caloric burn for the day seems very accurate.

Fitbit might need to change their algorithm with HR and calories burnt or something.

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With the HR functionality turned off it's only using steps to determine calorie burn.  If all you do is run or walk, then this would be accurate (assuming your stride length is set correctly).

For non-HR models, the calculation for calorie burn is distance (steps x stride)/ time to get your speed.  Then that is used to determine caloric burn.  You can test this by simply setting your stride length to double what it is normally then take a walk and you'll see a crazy number of calories burned.  

If you do a ton of non-step activity (weights, circuit training, Xfit) then your step based tracker is garbage.