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

[ForecasterJason]

@Vick_M

I get that, but here's the thing. Based on my calories burned while sleeping, I believe my Fitbit has my BMR around 1500-1600. From my understanding, a sedentary lifestyle with no intentional exercise can add several hundred more calories.

For this past Wednesday, my Fitbit said I burned around 3100 calories. I have a desk job, and on this particular day I did about 1-1.5 hours of intentional exercise. This includes a 2-2.5 mile run, some additional walking, and strength training. My total step count for the day was close to 14,000. So, this intentional exercise would have added up to 500 more calories.

Additionally, I have noticed my Fitbit shows my HR as being particularly elevated while I'm driving. While I think there is some truth to that, considering I'm not moving that much there's no justification for a 5X burn for the same time period as compared to what my BMR would be for the same time period (80 calories in 15 minutes vs 16 calories). 

I am 5'8" 125 lbs. Considering my size, I don't see any way how this is accurate. 

[ForecasterJason]

Thought I posted already but I don't see my post. 

@Vick_M I get that, but here's the thing. From my understanding, my Fitbit has my BMR being 1500-1600. On Wednesday, I did about 60-90 minutes of intentional exercise. This includes running, walking, and strength training. My total step count for the day was close to 14,000, but I spent a large portion of the day sitting. My Fitbit has my total calorie burn for the day being around 3100. Now, I do realize that a sedentary lifestyle would add a few hundred calories to the BMR, and my intentional exercise could have been another 500. But I don't see how I would end up with 1500 extra from what I did. 

Additionally, I have noticed that my Fitbit often shows my HR as being significantly elevated while I'm driving. That may be true, but there's no justification for how that would burn 5X as many calories over my BMR (80 calories in 15 minutes vs 16 calories in 15 minutes). 

For reference, I'm 5'8" 125 lbs. I just don't see any way how this is accurate. 

[Vick_M]

Your BMR is what you would burn if you stayed in bed the entire day. It
doesn't matter if you have a desk job, or if you spend hours driving.
Literally EVERYTHING you do while awake burns more calories than your BMR.

Your mistake is taking your BMR, adding your exercise calories, and a few
hundred more for additional steps, and thinking that's the math. It's not.
its why people wear fitbits. To get a more accurate calorie burn reading
than that old model estimate of BMR + Exercise.

I burned 4145 calories yesterday and my "intentional exercise" was about 45
minutes. I walked 15K steps and I had a day off from work yesterday. The
key is that I spent the whole day on my feet. Running errands. Cleaning
around the house. Cooking. Etc.

I hope that makes sense. Ignore your BMR, it means nothing except for the
hours where you're asleep. Every minute awake burns significantly more than
your BMR. So if you're BMR is 1,600 - and you're awake 16-18 hours in a
day, even without your exercise you're probably easily at 2,500 calories
burned just living a normal sedentary life.

[ForecasterJason]

I do understand that we burn a lot more calories than our BMR, but my issue is with the figures that my Fitbit is coming up with. Just yesterday, I went for a 16 minute brisk walk. My device automatically detected the walk and it put me at 103 calories burned. Later in the day, while driving, my Fitbit put my calories burned at 82 for a 15 minute block of time. By contrast, earlier in the day during a 15 minute block of time while driving my calories burned was at 27 (granted my HR was lower this time). And the 82 calories in 15 minutes while driving shows up as being "Moderate" activity. 

So, what this is telling me is that the calories burned is largely dependent on HR. But since HR can vary without any significant changes in movement (like what happened while I was driving), it seems to me as though the calories burned can easily be thrown off. I don't think it makes sense scientifically that I could have burned triple the number of calories in 15 minutes while driving simply because my HR was higher. Sure I may have burned a bit more, but not to that extent. 

[Minniemouse88]

I got my charge 2 at the same time (Dec 2016) and I'm finding the calorie burn figures quite accurate based on my maintenance being around 1800 and my rest days where I do minimal exercise I burn around 1800. 

I found that all the data became more accurate when I made the cardio fitness score more precise by following the instructions via the 'see how fit you are' / 'learn more' link under the heart rate data on the dashboard. It involved setting the fitbit up and going for a run where it uses the GPS and monitors your heart rate. 

Not sure if you've tried that but hope you're finding it more accurate. 

[gbstn10]

I don't know if this has already been mentioned, but I was browsing this topic as I had the same issue with Fitbit over-calculating my 'calories burned', and I realised, the formula being used by Fitbit is the Mifflin-St. Jeor Equation.

Basically, as far as I can ascertain, Fitbit use the M-S.J formula to calculate your BMR, then use multipliers to calculate your 'calories burned' based on activity tracked by the Fitbit device. For example, Fitbit calculated my BMR as 1716 kcal (which is correct), and based on what I did each day, they adjusted the multiplier to calculate 'calories burned'. 

Below are the standard 'activity' values for calculating energy expenditure after BMR has been calculated. Don't make the mistake of thinking that BMR +/- a few hundred calories is what you should be aiming for each day. The calculation is: BMR x the appropriate multiple listed below (based on what you do each day); that then gives you the amount of calories you need to eat to maintain your current weight (only from that number do you +/- a few hundred calories, depending on your weight goal).

If you are sedentary (little to no exercise), your BMR is multiplied by 1.2.

If you are lightly active (20+ minutes exercise 1-3 days per week), your BMR is multiplied by 1.375.

If you are moderately active (30-60 minutes exercise 3-4 days per week), your BMR is multiplied by 1.55.

If you are very active (60+ minutes exercise 5-7 days per week), your BMR is multiplied by 1.75.

If you are extremely active (intense training multiple times per day), your BMR is multiplied by 1.9.

The activity is also influenced by the work you do; for example, if you do manual labour, you would qualify for the very/extremely active multiplier groups even if you did less intense exercise. The multipliers basically measure how active you are when you're not sleeping.

My Fitbit numbers looked way, way off; and reading this topic (and others like it online), I assumed Fitbit was simply inaccurate. However, upon examining Fitbit's calculations, they look correct. My BMR is, as said, 1716 kcal. If I sit around doing nothing all day, my calorie intake should be a minimum of 2059 kcal (1716 x 1.2). If I use my Fitbit and log 13000 steps (6.16 miles), scale 15+ floors, and remain active in excess of 120 minutes (doing the 250 steps every hour for 14 hours, etc.), I would find myself in the 'very active' multiplier group (1.75) and my 'calories burned' should be around 3003 kcal. Fitbit logged my 'calories burned' as 3217 kcal.

Now, given there are independent studies that suggest these trackers can be around 10%-20% inaccurate, my Fitbit numbers seem about right. Considering there could be other calculations in play (related to the heart-rate monitoring, for example), Fitbit may be entirely correct in adding an extra 200 kcal.

Before I considered how active I actually was on that day (6 hours active vs 9.5 hours stationary; walking over 6 miles and squeezing in a workout that lasted 120+ minutes) I thought the numbers were insane. As it turns out, I was seriously over-active and only consuming enough calories to cover sedentary activity.

–

What I would recommend, if you want to check things for yourself, is calculating your BMR using the Mifflin-St. Jeor Equation, then multiply it (using the values above) to see which activity level most accurately matches the 'calories burned' calculation you take issue with in Fitbit. Then compare your activity that day to the requirements for that specific activity multiple and ask yourself if it seems accurate or not.

[Simon-b]

Sorry but that's not anywhere near right. 

The multipliers are based on *intense exercise* - 60 mins walking is vastly different to 60 mins high speed running. 

With what  you're listing you should have a multiplier of 1.375 -1.5 at best. Which mean Fitbit is *way* off. 

The whole point of these devices is to give you accurate data, but the Fitbit walking count is so bad it really throws everything off. Calculating it myself from scratch I think Fitbit gives approx 2x the credit for normal walking calories which it should. If you walk 10k steps in a day, and you're an average size and weight, that could be 300 calories difference easily. 

Fiitbit don't seem to be interested in addressing this problem though. 

[Papi1]

Hi guys. I'm 68 years old 5' 9" with  BMW of 34 and take np meds. So that tells you a lot Lol! I'm guess I that because of my body mass and higher bp I naturally burn more calories? 

What my FitBlaze which I just got last week, is that it keeps me motivated to get my 10 000 steps in daily. So I will see how it goes. Thanks for everyone's comments.

[Garod_T]

Agree with what you are saying. 

I'm pretty new at this and went for a 45 min walk with a short jog here and there and Fitbit told me I burned 830 calories. Reason was my HR was doing peak performance for some time during  the walk/jog. 

I just bought the fitbit, but if it's this inaccurate and they don't want to address this (which seems likely considering this thread goes back over a year) I'll be returning it right away and look for alternatives. 

[keengkong]

Me too.  It was about 400 calories per day higher than the Fitbit Flex.  (I wore two Fitbits, both linked to different accounts and phones).  

[Runner4131]

When my calories burned were way too high, I had entered my weight wrong.  I had entered 1,230.00 pounds by mistake instead of 129.00 pounds.  Kind of funny!   When I fixed my weight, then the calories burned went back to normal.

[EdinburghLass]

I've recently upgraded to the Fitbit Alta HR and my calorie allowance has increased significantly. I do 10000 steps a day and my allowance has increased from around 1700 (with the Fitbit One) to well over 2200. Today I switched the HR monitor off to see what happened and I went back down to my 1700 allowance. I notice that with the HR function on I regularly go into "Fat Burn" zone just doing gentle activity (I'm unfit!) so I think the Fitbit thinks I'm doing much more strenuous activity than I really am. Disappointed that I have to switch the HR function off as I could have saved money by just getting the Alta without HR to begin with!

[SunsetRunner]

I recently upgraded from the Alta (non HR) to the Charge 2. I was fully braced for an exorbitant calorie burn -at first- based on what I've read here and also that it takes a HR monitors a couple of weeks to "learn" you.

But so far, it  pretty much matches up with my Alta. So zero surprises or overestimates.

I'm happy with the Charge 2 

[Jimmy037]

Calories burned metric is ludicrously off on accuracy. Joke......

[bumpandrun]

BMR is a joke. It can't be figured with height/weight/age/sex because everyone's body is different. If I ate the calories I'm supposed to be able to eat to maintain my weight based on my BMR/activity level I would gain 10 pounds a month minimum.

[bumpandrun]

My Ionic is telling me that I'm burning almost twice as many calories for a 45 minute walk as my Garmin Vivoactive and I had to really watch what I ate with the Garmin numbers to lose weight. If I use the Ionic numbers I will blow up like a balloon.

[Mari83]

This is soooooooooo weird! My Charge 2 is understimating my calories burnt in more the 50% while working out when I compare to my chest strap device.

This is so desappointing...for some people Charge 2 overestimates, for others (like me) it understimates...I've tried to reset it, but still get the same problem. They certainly need to fix this. 

[oll_Gi]

All of you claiming overestimations or underestimations of Calories burnt did you check the HR measurements? Where they proper for what you were doing at the time?

In 40 mins walk with average 160 bpm ofc you will burn ton of calories. The problem is WHY and WHEN HEART RATE is recorded wrong, not the calories.

We need to gather our facts of WHY and WHEN this is happening.

I'm currently testing if my jacket/clothing push/press my Band out of proper place. Because when i wear short sleeves i think everything works fine.

[ForecasterJason]

A lot of the time, my HR reading is too high when the calories burned are elevated. However, that is not always the case.

Yesterday I went for a walk. In 18 minutes the average HR reading was 57% of my maximum, which I think should be close. The average calorie burn was reported as 6.7 calories per minute. Considering my BMR and the amount of METs from walking that pace, I don't think I actually burned more than 4.6 calories per minute. So for those 18 minutes, that's almost 40 calories off right there.

[oll_Gi]

@ForecasterJason

But don' look at the average. In all my walks if I open them and see the heart rate diagram I can see for some time the hr spikes. The average might look normal. But it's not since u say u burn 6.7 per minute. At some point it elevated more than it should.