Fitbit says I burn less than MFP

jquedal
jquedal Posts: 18 Member
in Health and Weight Loss
I am sure that Fitbit it probably more accurate, since it has my heartrate and steps etc, but has anyone else noticed, or know why a workout logged on MFP tells me I burned way more calories than Fitbit tells me I did during that time? They both know my correct weight/age/gender etc...

Replies

  • janejellyroll
    janejellyroll Posts: 25,763 Member
    Fitbit is monitoring your heartrate and is basing its estimate on that. MFP has no idea what your heartrate is for that exercise session, it has less data.
  • jquedal
    jquedal Posts: 18 Member
    I totally agree, but a difference of hundreds of calories? Seems kind of crazy to me. I do trust my Fitbit more though because of the hr monitoring.
  • nanastaci2020
    nanastaci2020 Posts: 1,072 Member
    edited November 2020
    I've heard many here comment that the database of exercise in MFP: is high on calorie estimates. I've rarely relied on it, so I don't know first hand.

    What are you doing in your workout and for how long? If you're doing a 20 minute workout vs a 2 hour workout: longer workouts have a greater room for error. What are you logging it as in MFP? That could be part of the issue. Some things have much variance. Like bike riding. You will burn a different # if its an exercise bike going casually, vs a spin bike going all out, vs a real bike riding in the real world with hills and such. So it could even be a scenario where the activity you selected in MFP is not the best one for what you're doing.
  • kshama2001
    kshama2001 Posts: 28,052 Member
    What is the exact exercise entry you are using on MFP?

    For example, I stopped using "Weight training, free weights" as it gives WAY more calories that "Strength training (weight lifting, weight training)"
  • heybales
    heybales Posts: 18,842 Member
    Are you comparing a manually entered workout using database entry to the Fitbit Adjustment that happens to appear in the Exercise Diary?
    Or to the actual workout as shown on the Fitbit app?

    Just wanting to confirm because I can't discern from your comments that you for sure know how the system works, and most don't when the see the Fitbit Adjustment line.

    As to why the difference - yes to everything already said.
    There's actually easier potential to have Fitbit inflated calorie burn.
  • GazelleLady
    GazelleLady Posts: 131 Member
    edited November 2020
    I use Garmin and I notice a similar phenomenon. Garmin uses my heart rate to calculate calorie burn, but sometimes I think it underestimates my heart rate (making it underestimate my calorie burn). Once, I ran 9 miles and Garmin said I only burned 400 calories. Fitbit may be doing something similar for you. If you want to test the accuracy, you might manually check your heart rate after/during a workout and see how it compares to the Fitbit reading.
  • AnnPT77
    AnnPT77 Posts: 34,168 Member
    GazelleLady wrote: »
    I use Garmin and I notice a similar phenomenon. Garmin uses my heart rate to calculate calorie burn, but sometimes I think it underestimates my heart rate (making it underestimate my calorie burn). Once, I ran 9 miles and Garmin said I only burned 400 calories. Fitbit may be doing something similar for you. If you want to test the accuracy, you might manually check your heart rate after/during a workout and see how it compares to the Fitbit reading.

    Heart rate only loosely correlates with calorie burn. Heart rate correlates with oxygen needs/consumption. The fitter you get, the fewer beats it takes to deliver the same blood volume or oxygen to the muscles. Running the same-terrain X miles at the same bodyweight requires roughly the same number of calories, no matter your heart rate, because what matters for calories is the amount of work (in the physics sense of "work"). As you get fitter, it take fewer heartbeats per minute to service the same amount of work, because there's more blood volume per heartbeat.

    Distance and body weight is a better correlate of calorie burn. Heart rate monitors can deceive, for sure aren't gospel.
  • heybales
    heybales Posts: 18,842 Member
    GazelleLady wrote: »
    I use Garmin and I notice a similar phenomenon. Garmin uses my heart rate to calculate calorie burn, but sometimes I think it underestimates my heart rate (making it underestimate my calorie burn). Once, I ran 9 miles and Garmin said I only burned 400 calories. Fitbit may be doing something similar for you. If you want to test the accuracy, you might manually check your heart rate after/during a workout and see how it compares to the Fitbit reading.

    This is excellent point especially for Fitbit.

    Some find the HR maxes out for Fitbit reading it and won't show higher, or it cuts out when it does go higher, so no value at all.

    One of the caveats of optical HR sensor. Moving it on wrist may help improve things. Or your arm is just a bad read.

    Whereas I'm getting static electricity spikes and elevated readings from an electrical Garmin chest strap as it gets cooler and drier while wearing poly.
  • slw37
    slw37 Posts: 89 Member
    My Fitbit calculates more calories burned than MFP. This is another reason why I don't "eat my exercise calories" back; I know they are not accurate.
  • heybales
    heybales Posts: 18,842 Member
    slw37 wrote: »
    My Fitbit calculates more calories burned than MFP. This is another reason why I don't "eat my exercise calories" back; I know they are not accurate.

    So a device that literally sees what you do each day is not as accurate as a calculation where you picked from 4 rough activity levels and no exercise is included?

    Because 1 value is higher than the other it must be the wrong value?
    The lower is the correct value?
    Based on......?
  • slw37
    slw37 Posts: 89 Member
    edited November 2020
    heybales wrote: »
    slw37 wrote: »
    My Fitbit calculates more calories burned than MFP. This is another reason why I don't "eat my exercise calories" back; I know they are not accurate.

    So a device that literally sees what you do each day is not as accurate as a calculation where you picked from 4 rough activity levels and no exercise is included?

    Because 1 value is higher than the other it must be the wrong value?
    The lower is the correct value?
    Based on......?

    I don't pick from any "activity levels". I look at what MFP imports from Fitbit and compare it to what the Fitbit app shows as far as calories burned. They don't match.

    I did not ask for anyone's opinion or advice, but thanks for playing.
  • SCoil123
    SCoil123 Posts: 2,110 Member
    jquedal wrote: »
    I totally agree, but a difference of hundreds of calories? Seems kind of crazy to me. I do trust my Fitbit more though because of the hr monitoring.

    MFP was giving me near double for workout burns than what FitBit said so I stopped logging workouts here. I have FitBit synced and use that instead. It’s worked well

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