Fitbit vs HRM.... Hugely inconsistent

gemmaleigh1989
gemmaleigh1989 Posts: 241 Member
in Fitness and Exercise
So I went for an hour walk with my fitbit and HRM (polar ft60). Before I left, my fitbit calorie adjustment for the day was 70 cals. So by the end of my walk, my HRM said I burned 160 calories (I don't weigh very much, hence the low number). So I get back and before I log my walk, my fitbit adjustment is now 440. So that's an adjustment of 370 calories just from my walk where my HRM says 160 calories :l. Usually I wouldn't mind and understand they're just estimations but this is a huge difference and makes me think fitbits are really inaccurate re calorie burn :( am I doing something wrong? I opted for the lower number so logged my walk manually with my HRM reading but I'd like my fitbit calorie reading to be accurate for all the other hours in the day. Please help!

Replies

  • BrianSharpe
    BrianSharpe Posts: 9,248 Member
    Given that it was a 1 hr walk I would lean in favour of the HRM (to sanity check caloric expenditure walking Runners World suggests the following formula - sorry, it's not metric - .30 x weight in lbs x distance in miles - for net calories expended)

    assuming you walked briskly at 4mph / 6 kmh and given the wight on your ticker of 47kg / 103lbs your net expenditure would have been approximately 124 cal.
  • gemmaleigh1989
    gemmaleigh1989 Posts: 241 Member
    Thanks, so why has the fitbit given such a ridiculous number? I don't expect it to be 100% accurate but I hope it to be close so I know what calories to eat back when I surpass "sedentary" throughout the day :l
  • johnthomasmoore
    johnthomasmoore Posts: 59 Member
    Check: https://help.fitbit.com/customer/portal/articles/898903-how-does-fitbit-know-how-many-calories-i-ve-burned-

    As I understand it your comparison of calories between the HRM and the Fitbit may rest on a faulty assumption: that only the walk calorie expenditure is being compared. I could be wrong, I think the heart rate monitor gave you calories for the walk and the fitbit gave you calories for revised estimate of daily expenditure.

    I believe that HRM are good for estimating cardio workouts. The fitbit is good for steps and overall daily activity (especially if you manually log activities where steps are not so relevant.

    All the best.
  • trackercasey76
    trackercasey76 Posts: 781 Member
    The FB may not have Synched recently and did after you got back from your walk.
  • gemmaleigh1989
    gemmaleigh1989 Posts: 241 Member
    The FB may not have Synched recently and did after you got back from your walk.

    Nope, I synced it immediately before my walk and then again afterwards
  • gemmaleigh1989
    gemmaleigh1989 Posts: 241 Member
    Check: https://help.fitbit.com/customer/portal/articles/898903-how-does-fitbit-know-how-many-calories-i-ve-burned-

    As I understand it your comparison of calories between the HRM and the Fitbit may rest on a faulty assumption: that only the walk calorie expenditure is being compared. I could be wrong, I think the heart rate monitor gave you calories for the walk and the fitbit gave you calories for revised estimate of daily expenditure.

    I believe that HRM are good for estimating cardio workouts. The fitbit is good for steps and overall daily activity (especially if you manually log activities where steps are not so relevant.

    All the best.

    Nope, I was only comparing calories burned on the walk. As I said, adjusted fitbit calories before walk = 70. After walk = 440. Means it think I burnt 370 on the hour walk.
  • brianpperkins
    brianpperkins Posts: 6,124 Member
    Check: https://help.fitbit.com/customer/portal/articles/898903-how-does-fitbit-know-how-many-calories-i-ve-burned-

    As I understand it your comparison of calories between the HRM and the Fitbit may rest on a faulty assumption: that only the walk calorie expenditure is being compared. I could be wrong, I think the heart rate monitor gave you calories for the walk and the fitbit gave you calories for revised estimate of daily expenditure.

    I believe that HRM are good for estimating cardio workouts. The fitbit is good for steps and overall daily activity (especially if you manually log activities where steps are not so relevant.

    All the best.

    Nope, I was only comparing calories burned on the walk. As I said, adjusted fitbit calories before walk = 70. After walk = 440. Means it think I burnt 370 on the hour walk.

    It means 370 gross calories during the hour walk. Fitbits include BMR in their rolling caloric total throughout the day.
  • gemmaleigh1989
    gemmaleigh1989 Posts: 241 Member
    ^That's not right either though because my Bmr is about 50 calories an hour which means fitbit reading should have been about 210 odd
  • starjulia
    starjulia Posts: 22 Member
    If you actually go to the fitbit website or the fitbit app on your phone then you can see a more real time view of your calories burnt during your walk. The adjustments made on myfitnesspal assume that you are going to be active all day. It will take away from that adjustment throughout the day or add to it depending on your activity level. At least that is how I have seen mine work.
  • mslaurza
    mslaurza Posts: 13 Member
    I returned my fitbit after about a week - seemed to be way off. The accelerometer judges your activity level meaning that when I clapped my hands after the ballet, it recorded that as some intense activity! Granted its more fun to use than a hrm, but that's only because of the fancy dashboards, sleep 'tracker' and lots of calories burned. I would go with the hrm. Good luck!

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