fitbit calorie adjustment vs what my HRM says

hanneberries
hanneberries Posts: 119 Member
in Fitness and Exercise
I just got my fitbit yesterday, however, I've been using an HRM for quite some time.

I've read a lot about how people don't add things like walking etc to their log, as the fitbit is usually accurate. However, for me, my fitbit calorie adjustment was about 300cals lower than what my HRM said. My HRM is set up with my age, weight, height and sex, and is set to a few KG lower than my current weight.

Since the difference is quite significant, I deleted the FBCA, and added what my HRM said.

Is that wrong, or is it just something that is up to me? Why would my difference be so great, when everyone else seems to just have a few calories off?

ETA: I only use my HRM when I go for walks, which are my daily cardio exercise.

Replies

  • therealangd
    therealangd Posts: 1,861 Member
    Your HRM is not calibrated to be used as an all day tool.

    But besides that I personally would have taken the lower amount to be conservative.
  • hanneberries
    hanneberries Posts: 119 Member
    I don't use my HRM all day, just when I go for exercise walks.
  • kjw1031
    kjw1031 Posts: 300 Member
    I would also go with the lower number, just to try to be sure that I'm not over-estimating calories burned.
  • flynnfinn
    flynnfinn Posts: 209 Member
    i say split the difference. i wear my HRM only for exercise and most if not all my exercise is power walking uphill pushing a 3 year old 16kg boy in his buggy/stroller (which also weighs an additional 10kg). so trust me...i am workin' it. my heart rate registers anywhere between 120-175bpm as far as fitness/cardiovascular exercise and 90-119bpm for my resting heart rate and on the downhills. i too have my HRM set for my exact age and height and my weight is set 5kg less than my actual weight. so there is already margin for error.

    today, i walked for 140 minutes at a very brisk pace up and downhill and my HRM said i burned 856 calories. MFP says it should be 813 calories. so i average it around 830 calories. and for those that do not consider power walking a form of exercise, think again because i could hardly talk to my husband while we were walking.
  • hanneberries
    hanneberries Posts: 119 Member
    I don't even check what MFP says anymore, since I've had my HRM, hah. But I'm only using it for when I power walk, as you flynn, and I'm out of breath the whole time but I keep at it, averaging a pace of about 4.6 miles per hour, though I always run down the hills, which usually brings me up to about about 6MPH according to Endomondo. Endomondo is usually just 20-30cals over what my HRM says, and Endomondo is a GPS tracker that measures how fast I'm going, how far, telling me how long I use on each KM.

    The fitbit only measures steps though, does it not? Meaning it can't register how hard I'm working, which makes me think it's off more than the HRM?
  • Azdak
    Azdak Posts: 8,281 Member
    Your HRM must be set with your actual HRmax and actual VO2max in order for it to be the most accurate it can be (probably about 80%). If you don't know those numbers, or don't have them programmed into the HRM, then you don't really know if the HRM is all that accurate.

    That being said, I don't think the Fitbit is all that accurate for estimating exercise calories. Endomondo records speed which, if you were on a treadmill, or level surface outdoors w/no wind, would likely be the more accurate estimate, but it cannot account for terrain (and downhill speed will likely overestimate calories.

    So, if I had to settle on one answer, I would say that the fitbit is underestimating and the HRM is overestimating.
  • LeellenMack
    LeellenMack Posts: 141 Member
    The fitbit can't account for your heart rate it uses the information you programmed in when you set it up height, weight, etc. It is meant to count steps and then use these measurements to account for the number of calories burned. The HRM also takes into account your heart rate so should be more accurate however, everything I've read shows the fitbit usually is within 100 calories +/- of HRMs on calorie burns so you may want to check your settings on each.
  • hanneberries
    hanneberries Posts: 119 Member
    Your HRM must be set with your actual HRmax and actual VO2max in order for it to be the most accurate it can be (probably about 80%). If you don't know those numbers, or don't have them programmed into the HRM, then you don't really know if the HRM is all that accurate.

    That being said, I don't think the Fitbit is all that accurate for estimating exercise calories. Endomondo records speed which, if you were on a treadmill, or level surface outdoors w/no wind, would likely be the more accurate estimate, but it cannot account for terrain (and downhill speed will likely overestimate calories.

    So, if I had to settle on one answer, I would say that the fitbit is underestimating and the HRM is overestimating.

    My HRM is set with my resting heart rate (57) and my max heart rate (according to the 220-age which for me is 197) but not VO2max.

    Yes, that's what I thought, too, you see. the route I take goes over a hiking trail, meaning there's inclines and declines, and different terrain throughout, though I would say 90%flat.

    That makes sense, although I believe I will stick to my HRM. I don't eat back all my exercise calories anyway, but they're nice to have.
  • hanneberries
    hanneberries Posts: 119 Member
    The fitbit can't account for your heart rate it uses the information you programmed in when you set it up height, weight, etc. It is meant to count steps and then use these measurements to account for the number of calories burned. The HRM also takes into account your heart rate so should be more accurate however, everything I've read shows the fitbit usually is within 100 calories +/- of HRMs on calorie burns so you may want to check your settings on each.

    Well, my HRM is set to 3kg less than my fitbit is, but other than that, they're the same? Hm.
  • flechero
    flechero Posts: 260 Member
    I 'think' there are a couple things you should look at. First, is your fitbit calibrated to your stride length? That can make a big difference. (in fitbit go to settings then personal settings to input stride lengths)

    Secondly, the MFP adjustment from fitbit never matches the time or activity- I think because fitbit only counts the exercise, not the total cal usage- meaning you'll still burn cals if you were idle in that time period.

    And lastly, MFP and fitbit differ on cals you should eat so there is some flux in what they count for each other.


    I just got a HR monitor so I can't help on one vs. the other just yet.
  • hanneberries
    hanneberries Posts: 119 Member
    Thanks for all your help, guys!

    I went on another walk today, and today the fitbit and HRM were only off by about 50cals, so I guess yesterday was just a fluke or something, haha.
  • dlwyatt82
    dlwyatt82 Posts: 1,077 Member
    FitBit's adjustment only reflects the difference between what the FitBit says you burned and what MFP thought you burned. If the FitBit's count is higher, MFP's numbers get nudged up slightly.

    It seems to be more accurate to log your exercise on the FitBit website rather than MFP, and log food on MFP, for that reason. For example, let's say your MFP estimated calories for the day (based on your BMR and activity level) are 2000 before exercise, but in fact, due to overestimation, you only burned 1800. Then you go out and jog for a while, burning 500 extra calories.

    If you log the exercise on the FitBit site, you'll wind up with a total calorie burn of 2300 (1800+500), and you'll get a FitBit adjustment on MFP of 300 calories (the difference between your actual total burn of 2300 and MFP's original estimate of 2000).

    If you log the exercise on MFP, it will say your total calorie burn is 2500 with NO FitBit adjustment. MFP will add your exercise calories to its original estimate of 2000, carrying that original overestimation through to the end.

    With that in mind, I just let the FitBit side be in charge of figuring out my calories burned, and MFP tracks calories consumed.

    Edit: I guess I should explain why I typed all that. In your original post, you said that your "FitBit calorie adjustment" didn't agree with your HRM. The calorie adjustment is something different, though. If you start and stop the stopwatch function on your fitbit when you take your walk, then synch it at home, you can look at the FitBit site (under "Activities") to see how many calories it thinks you burned during that period (which is almost certainly not going to be exactly the same number of calories MFP logs as an adjustment.)

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