Massive calorie overestimate

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New_Heavens_Earth
New_Heavens_Earth Posts: 610 Member
edited August 2018 in Health and Weight Loss
I walked 20 minutes at an average of 3mph as per Samsung Health. It gave me a 70 calorie burn estimate. Sounds right. MFP gave me the same calorie estimate. My Fitbit? 120. I wonder how long its been overestimating like this, but more importantly how do I fix this and which source to believe? I set up Samsung health out of curiosity, I don't use it regularly. My weight is still fluctuating +/- 2 to 3 lbs, but Libra is still showing a downward trend.

Any help is appreciated. Thanks.

ETA: I just walked 17 minutes back and got the same results, a 50 calorie overestimate from Fitbit.
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Replies

  • stacimarie1015
    stacimarie1015 Posts: 30 Member
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    I don't know your stats or how much effort went into your walk. Strolling aimlessly or heart really pumping? But does a tad over 2 cals per minute seem reasonable based on your resting heart rate? It seems a little low to me, if you were putting out enough effort that your heart rate was up.

    Have you been using the Fitbit stats in deciding your deficit, and if so - have you been losing slower than anticipated? If your weight loss/maintenance has been on target AND you've been using the Fitbit #s then that supports the theory that your Fitbit is relatively accurate.
  • New_Heavens_Earth
    New_Heavens_Earth Posts: 610 Member
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    stacimarie1015 wrote: »
    I don't know your stats or how much effort went into your walk. Strolling aimlessly or heart really pumping? But does a tad over 2 cals per minute seem reasonable based on your resting heart rate? It seems a little low to me, if you were putting out enough effort that your heart rate was up.

    Have you been using the Fitbit stats in deciding your deficit, and if so - have you been losing slower than anticipated? If your weight loss/maintenance has been on target AND you've been using the Fitbit #s then that supports the theory that your Fitbit is relatively accurate.

    I was walking at a decent pace, about 100 to 136 bpm HR. I have been losing less than my 1 lb per week goal. I have been eating back some calories from the Fitbit, about half.

    Stats
    5'3"
    150 lbs trying to get to 125
    Started from 208 lbs
  • New_Heavens_Earth
    New_Heavens_Earth Posts: 610 Member
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    yirara wrote: »
    Heart rate doesn't correlate well with calorie burn, really. Someone just needs to be very unfit, and as such a walk would result in a higher heart rate, but not a higher calorie brun. And likewise, there's also fairly little correlation with speed. Walking and running on flat terrain are mostly a function of bodyweight and distance. For walking, try

    bodyweight in lbs * distance in miles * 0.3

    Thanks. That formula gave me 45 calories (walked about a mile in each direction).
    I think it's safer to low ball the estimate.
  • heybales
    heybales Posts: 18,842 Member
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    If this is within the first couple weeks of using Fitbit, it's still adjusting the HR-based calorie formulas to your specifics.

    Though as mentioned above - the database entries (especially Fitbit's) based on weight and distance have better accuracy.

    Mainly the device is going to try to figure out when NOT to use the HR-based, and purely use step-based formula for daily activity level calorie burn. So if unfit and shooting the HR up, or medical condition, or stressed - inflated calorie burn for daily stuff.
    Once it has idea of cut-off, and you don't shoot the HR up too high for long enough - it'll use better step-based.

    The HR-based can be the best bet on other cardio activities where no other good formula can be used, and database entries have no intensity level associated with it.

    You can fix it by manually logging on Fitbit any walks where you know the distance and noted the start/duration time. Or....
    You can leave the Fitbit created Activity Record, as the calorie info will be overwritten by your Workout record in the daily burn stats anyway. Their Activity Record can give you the start/duration time to use actually on your Workout Record.

    To see if it's using the HR-based formula during the daily activities when it shouldn't - just look at your daily graph with 5-15 min increments, calorie burn tab, and see if any big spikes correlate to merely walking a tad faster, or stairs, or up hill, but still not exercise level.
  • New_Heavens_Earth
    New_Heavens_Earth Posts: 610 Member
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    heybales wrote: »
    If this is within the first couple weeks of using Fitbit, it's still adjusting the HR-based calorie formulas to your specifics.

    Though as mentioned above - the database entries (especially Fitbit's) based on weight and distance have better accuracy.

    Mainly the device is going to try to figure out when NOT to use the HR-based, and purely use step-based formula for daily activity level calorie burn. So if unfit and shooting the HR up, or medical condition, or stressed - inflated calorie burn for daily stuff.
    Once it has idea of cut-off, and you don't shoot the HR up too high for long enough - it'll use better step-based.

    The HR-based can be the best bet on other cardio activities where no other good formula can be used, and database entries have no intensity level associated with it.

    You can fix it by manually logging on Fitbit any walks where you know the distance and noted the start/duration time. Or....
    You can leave the Fitbit created Activity Record, as the calorie info will be overwritten by your Workout record in the daily burn stats anyway. Their Activity Record can give you the start/duration time to use actually on your Workout Record.

    To see if it's using the HR-based formula during the daily activities when it shouldn't - just look at your daily graph with 5-15 min increments, calorie burn tab, and see if any big spikes correlate to merely walking a tad faster, or stairs, or up hill, but still not exercise level.

    I've had this Fitbit for almost a year. This is the first time I noticed a discrepancy because I just trusted them before (had a non HR model previously).

    I just checked those graphs, which I never knew were there (duh), and saw several spikes in calories burned and HR. A couple said "very intense" , but I did nothing intense at all. I just took the stairs, or walked fast.

    Thanks for this info!
  • Seffell
    Seffell Posts: 2,222 Member
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    My firbit overestimated my burns by about 300-400cals per day which is more than my deficit. And that was with me only walking. I think the reason was that my heart rate is higher. I was slowly gaining so I dumped it after several months.
  • New_Heavens_Earth
    New_Heavens_Earth Posts: 610 Member
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    gebeziseva wrote: »
    My firbit overestimated my burns by about 300-400cals per day which is more than my deficit. And that was with me only walking. I think the reason was that my heart rate is higher. I was slowly gaining so I dumped it after several months.

    Wow. I just checked MFP vs Fitbit for this evening's workout. Came out to about 170 calories overage on Fitbit's side. I think I might disconnect it from here, manually enter exercise, and see what happens after a month or so.

    Thanks to all.
  • mkculs
    mkculs Posts: 316 Member
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    That sounds like a good plan. Congrats on your progress! Those discrepancies make a bigger difference now, I bet, b/c you are so close to goal and the difference between your deficit and maintenance calories is probably getting smaller.
  • heybales
    heybales Posts: 18,842 Member
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    WholeFoods4Lyfe wrote: »
    FitBit is calculating your entire calorie expenditure for that 17 minutes while other sites are only estimating the calorie burn in excess of your TDEE.
    WholeFoods4Lyfe wrote: »
    FitBit is calculating your entire calorie expenditure for that 17 minutes while other sites are only estimating the calorie burn in excess of your TDEE.

    Curious what other sites would have enough stats to know your TDEE, in order to give you a calorie burn that is ONLY over your TDEE? (that ain't MFP)

    I know of 2 sites that even give an option of selecting NET calorie burn for walking, not even other exercises. Otherwise it's Gross burn across the board.
  • New_Heavens_Earth
    New_Heavens_Earth Posts: 610 Member
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    mkculs wrote: »
    That sounds like a good plan. Congrats on your progress! Those discrepancies make a bigger difference now, I bet, b/c you are so close to goal and the difference between your deficit and maintenance calories is probably getting smaller.

    Thanks! This exactly! I understand the value of patience, but I feel like my deficit wasn't enough and things are getting tight with the exercise calories and accurate logging
  • lorrpb
    lorrpb Posts: 11,464 Member
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    WholeFoods4Lyfe wrote: »
    FitBit is calculating your entire calorie expenditure for that 17 minutes while other sites are only estimating the calorie burn in excess of your TDEE.

    No, not your TDEE, your NEAT.
  • yirara
    yirara Posts: 9,420 Member
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    gebeziseva wrote: »
    My firbit overestimated my burns by about 300-400cals per day which is more than my deficit. And that was with me only walking. I think the reason was that my heart rate is higher. I was slowly gaining so I dumped it after several months.

    For some reason I get fairly good calorie estimates for bodyweight/interval type workouts and for running and walking if I delete the logged workout and relog it on fitbit :o Maybe because the fitbit uses HR measurements for the original activities, and not anymore for manually logged exercises. So maybe it uses 0.3*weight*distance for walking instead of taking my higher heartrate into the equation somehow. Who knows...

    But other than that my calories tend to be too high for days I don't workout as well.
  • New_Heavens_Earth
    New_Heavens_Earth Posts: 610 Member
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    Well I did do a half hour jog later on yesterday and got an over 400 calorie burn. Something isn't right. Time to reevaluate.
  • yirara
    yirara Posts: 9,420 Member
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    New_Heavens_Earth wrote: »
    Well I did do a half hour jog later on yesterday and got an over 400 calorie burn. Something isn't right. Time to reevaluate.

    If it was mostly on flat terrain then you could try using approximately 0.67 * distance in miles * weight in lbs and compare. If you were really running fast and covered a lot of distance then it might be true. But more likely it's overstating :(
  • heybales
    heybales Posts: 18,842 Member
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    Also be aware if all you are looking at is the MFP created Fitbit adjustment - that is NOT the calorie burn of the workout at all.

    That adjustment is merely MFP correcting itself to match what Fitbit reported for daily burn, so literally:
    Fitbit daily burn - MFP estimated daily = adjustment.

    That adjustment is added to your eating goal. Extra math is done during the day.

    That could be huge workout but very lazy and no adjustment.
    Or no workout and very active daily and big adjustment.
    Or combo of workout and active.

    Or are you saying Fitbit, in their stats for that workout, reported a 400 cal burn for 30 min?

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