Fitbit...do you trust the numbers?

thanos5
thanos5 Posts: 513 Member
in Fitness and Exercise
i have my mfp account linked with fitbit.

do you trust the numbers that show up for mfp exercise from fitbit?

i keep a spreadsheet with my daily weight, calories in, and calories out. when i do the math for the past 2 months, i should have lost 8 lbs (says i burned approx 28,000 calories). i lost 4. i'm meticulous about my logging, i do not believe it is a logging error. especially to be that far off.

according to my math, fitbit is giving me 43% more calories burned than i am actually burning.

i'm thinking about unlinking my fitbit account and changing from sedentary to lightly active, then just entering my exercises into mfp directly but was wondering if you all had any thoughts or suggestions?

example, today:
4.5 on the treadmill for 24 minutes
5.0 on the treadmill for 16 minutes
casual walking, about 1/2 hour (walked some laps, went to charbucks)

mfp gives me about 381 calories burned for the 2 exercises, and obviously, zero for the casual walking
fitbit has given me 817 total burned for the 2 exercises plus my casual walking

Replies

  • NorthCascades
    NorthCascades Posts: 10,968 Member
    O fine have a Fitbit and can't say anything on that front, but the math you did and the thinking behind it are both correct.
  • Justin_7272
    Justin_7272 Posts: 341 Member
    Does your FitBit have a heart rate monitor? Does your treadmill have a heart rate monitor? HRM is by no means a 100% gauge of calories burned, but can be a useful tool.

    FWIW you'd have to be at extremely high intensity to burn 800+ calories with 40 min. treadmill + 30 min walk.
  • heybales
    heybales Posts: 18,842 Member
    Have you made any of the tweaks to Fitbit to improve it's chances of being more accurate?

    If you get a lot of daily steps - have you ever walked a known 1/2 to 1 mile distance at avg daily pace (like 2mph) and confirmed Fitbit saw the distance right?

    Does it seem like your HR heads up above 90 for just some normal daily walking levels?
    That likely means Fitbit is switching to HR-based calorie burn - which is going to be inflated for that level of effort.
    Because even that 4.5 & 5 mph walking or running would be more accurate from pace calculation than HR-based.
    You could use the Activity Record that Fitbit creates to get the start/duration time, and go in and create a Workout Record that matches for time/duration - but then enter distance done and it'll give you calculated calories instead.
    And since Fitbit is replace only system, your last manual Workout replaces the prior Activity for calories in the daily total - which will be sent to MFP to do math with.

    If you have medicine induced elevated HR that may benefit from disabling the HR-monitoring except during checks you want to do, but not all day on.

    Those are just a couple of simple things to try to get more accuracy.

    But indeed may need to tweak some things with a known offset if it looks that way.
  • thanos5
    thanos5 Posts: 513 Member
    thanks for the insight. yeah, it has a HRM, but i'm prone to panic attacks...i once woke up with 500 exercise calories burned...so i think it's considering things exercise that are not.

    some good advice, @heybales, thanks. i know these things aren't 100% accurate, i expected the numbers to be off...just didn't expect them to be off by 43%.
  • kmfeig87
    kmfeig87 Posts: 1,990 Member
    I'm assuming
    thanos5 wrote: »
    i have my mfp account linked with fitbit.

    do you trust the numbers that show up for mfp exercise from fitbit?

    i keep a spreadsheet with my daily weight, calories in, and calories out. when i do the math for the past 2 months, i should have lost 8 lbs (says i burned approx 28,000 calories). i lost 4. i'm meticulous about my logging, i do not believe it is a logging error. especially to be that far off.

    according to my math, fitbit is giving me 43% more calories burned than i am actually burning.

    i'm thinking about unlinking my fitbit account and changing from sedentary to lightly active, then just entering my exercises into mfp directly but was wondering if you all had any thoughts or suggestions?

    example, today:
    4.5 on the treadmill for 24 minutes
    5.0 on the treadmill for 16 minutes
    casual walking, about 1/2 hour (walked some laps, went to charbucks)

    mfp gives me about 381 calories burned for the 2 exercises, and obviously, zero for the casual walking
    fitbit has given me 817 total burned for the 2 exercises plus my casual walking

    I'm assuming the 28,000 calories burned is difference between total you burned and what you ate?
  • thanos5
    thanos5 Posts: 513 Member
    yeah, i should have stated that the 28000 is a deficit.
  • hesn92
    hesn92 Posts: 5,966 Member
    When I sync it to mfp I trust the calories it's tell me to eat. I have gone off of those numbers in the past and everything worked out just fine. My fitbit has a HR monitor on it. I don't pay attention to how many calories it's telling me I burn from any specific activity. The total # of calorie would include the number of calories I would have burned doing nothing as well, which is why it's a higher number than what MFP would give. But I don't log exercises into MFP at all, I just let it sync and add/subtract to my overall calorie goal.
  • NorthCascades
    NorthCascades Posts: 10,968 Member
    Justin_7272 wrote: »
    Does your FitBit have a heart rate monitor? Does your treadmill have a heart rate monitor? HRM is by no means a 100% gauge of calories burned, but can be a useful tool.

    FWIW you'd have to be at extremely high intensity to burn 800+ calories with 40 min. treadmill + 30 min walk.

    More specifically, you'd have to be at a very high speed to burn that many calories that quickly. You can calculate walking and running calorie with good accuracy by doing a mass over distance calculation. Fitbit knows your mass and stride length. Heart rate not required or very useful here, honestly.

Categories