Calories burned is way off

[S.ari]

I have a charge 6 and it's not calculating my calories burned accurately.  It says that I'm burning under 300 calories during a gym class, while the heart rate monitor I'm wearing around my chest is calculating over 600.  When I look at the heart rate I had during the class I'm up in the 'peak' for the majority of the time, and I've been comparing the heart rate been the two monitors and they are very close.  

Any one know how to fix this?  

Thanks!  

[JohnnyRow]

You don't give us much information to work on.  The first obvious question is: when the 2 are giving such close heart rate readings, why are you assuming that it is the fitbit that is wrong?  When 2 systems are off by that much, the first thought is that one is getting bad heart rate readings, but not the case here.  With error off that much, the second thing I would look for is if you have input incorrect personal information into one of the systems.  Another thing I would check is what the 2 systems have measured for the length of the workout.  We don't know if you manually started and stopped the workouts or relied of the 2 systems to detect the start and stop.  Check that they both started and ended at approximately the same time.

[S.ari]

Thank you for replying!  

I have checked my personal information, and it is accurate.  Both monitors are reading for the same time (I don't manually start and stop my fit it, but it will read that I'm working out bc of the elevated heart rate and then I go in after the fact to update it with the workout type and time, making sure that it matches my other monitor). 

And to answer your question, I'm assuming that the fitbit is off because 250 calories seems pretty low for a 50 minute workout where my average BPM is 155.   

[JohnnyRow]

A)  When you say you checked your personal info, I hope you mean on both systems, not just on Fitbit.

B) I would feel more comfortable if I knew you were checking the Fitbit calorie count before you go in and start updating the data.

C) It's hard for me judge whether 250 or 600 calories seems more reasonable with no idea if you weight 75 or 275 pounds, or are 13 or 73 years old.

Edited to add: Other than that, I don't know.  I don't necessarily mean to sound too skeptical but if it really were off that much, it wouldn't just be the Charge 6.  That would mean the whole Fitbit algorithm for calculating calorie burn for all Fitbit models is over 50% too low.  That is almost too much for me to believe without a huge, huge, huge outcry about it, here and in any journals that cover wearables.

[S.ari]

Yup!  Checked both (my Fitbit and heart rate monitor).  

Not sure what you mean about checking it before starting the workout... This has been going on since I got the Fitbit 3/4 weeks ago.  I checked my personal info and have been trying to figure this out since then.  And if it helps you judge... I'm a 37 year old female that weights 135lb.  

[JohnnyRow]

Before starting updating workout type and time after the workout. I say that because if you manually log a workout after the fact, it ignores all the data that was actually recorded.  It it as Fitbit assumes the reason you manually logged the workout after-the-fact is because you were not wearing the tracker during the workout, so it guesses at your heart rate based at the parameters you input.  I don't know if that is also what happens when you edit the workout.  That is why I suggest you check the calorie burn immediately after the workout before you go back in and start editing anything.

Just at least once, leave everything just as it is, even if it not the workout type you wish it was, and see what you get.  Or even better, use the Exercise App on your wrist to start and start it to get the exact times, and choose what you want to call it.

  Note what I added to previous post just as you were posting.

[S.ari]

Yea... I usually check it before editing, and it's hugely off even before I change it (I typically just change the exercise type and add a few minutes... I don't change that much, and I've tried changing the calories manually, but it won't let me).  I'll try starting it on my wrist for tomorrows workout though.  

I agree that if the whole fit it algorithm is off it would be a huge thing and others would be talking about it... That's why I'm so confused.  

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By the way... Thanks for responding and giving me advise.  

[JohnnyRow]

Sorry if my "advice" all sounded negative.  Let me know what happens. Now I'm curious.  About all I do any more is more frequent shorter lower intensity indoor walks so not getting that type experience lately to be able to judge if that would be happening to me.

[S.ari]

I tried starting to workout on my wrist, but no dice, it was still off by quite a bit (compared to my monitor around my chest).  It remains a mystery...

[JohnnyRow]

You started and stopped it on your wrist, and did not edit it. Is that correct?  It's the editing I am concerned about, and using the Exercise App was to eliminate the need to edit the workout.

[S.ari]

Correct.

Also, when I do edit a workout, it always has a calorie count for the time it detected a workout before I hit edit.  

[ThomasFM]

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@JohnnyRow wrote:

Edited to add: Other than that, I don't know.  I don't necessarily mean to sound too skeptical but if it really were off that much, it wouldn't just be the Charge 6.  That would mean the whole Fitbit algorithm for calculating calorie burn for all Fitbit models is over 50% too low.  That is almost too much for me to believe without a huge, huge, huge outcry about it, here and in any journals that cover wearables.

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The fit bit algorithm could be inaccurate. For my example; I was using a third party brand, no idea the actual name, before November and most of the time it was giving me between 400 - 800 kcal burned for 15 - 18k steps taken for that day.
But since november I've switched Fitbit Sense 2 and there seems to me several differences with it. One the individual walking sessions i do for cardio tends to show the 250 - 750 calories burned for a 25 - 45 minute sessions. Then you get on both the app and watch "4685 calories burned" after 15k steps but it shows a completely different burn number of "you burned 1450 of your 4685 calories".

I feel like fitbit could have made it more streamlined with just showing you how much you actually burned and not add in other category of calories burned that claims you burned 4.5 - 5k calories. Because on average i tend to get 16 - 18k steps per day on 5 days a week, which in total gives me over 80k steps on my app. Which then adds in on another window "30k calories burned this week" which for me is really 5 days because assuming that could be accurate that would mean before food in take is added i could be burning off 8lbs of fat in 5 days which sounds extreme for people and I'd be seeing insane unhealthy fat loss and i've been doing this since getting sense 2, by this logic i could have potentially lost 103lbs in 3 months which clearly not what happened; Even if you add the foot in take that drops to about 45lbs in 3 months. If only it actually did that. lol

Not to hijack the thread but I do believe there's something amiss with how the fitbit tries to tell you how much you truly lost in calories, as someone who's trying to burn off body fat this doesn't seem accurate at all; hypothetically i could have burned off all the food I ingested for that day but really only losing third of a pound.

Not to mention that a 45 minute walk is not consistent, some times the app shows it's 60 - 80% fat burn session other times it's simply cardio and no fat burn.
All in all i feel like these watches and apps are a good idea of what to look out for but I don't really know if it's accurate; other than the BPM which from my experience as well as the sleep tracker is definitely accurate.