question: Machines that calculate calories burned (FitBit)

snargaluff
snargaluff Posts: 6 Member
in Health and Weight Loss
I've tried to research my question but was unsuccessful, so apologies if this has already been answered somewhere...

I was wondering that even if pedometer like devices (I have a fitbit) calculate calories burned using the BMR, isn't BMR different for everyone, so how would they know (roughly estimating) that that is the amount of calories I burn?

I know they also ask for like weight, age, height etc. so maybe my question is still unclear.
I am a 22 year old female, 5 ft. 4 inches tall, 145 lbs currently, sedentary throughout the day except when exercising.
does that mean my BMR and metabolism is pretty much the same as another sedentary 22 yr old female of the same weight and height? Is it possible that there could be a significant difference depending on other circumstances?

Like if I was a type 1 diabetic (which I am) could my metabolism be lower than a normal person and therefore my calories burned is lower, aka my fitbit is wrong for me personally? or can I trust the numbers on my fitbit device?

I'vee just been paranoid a lot lately, and want to use MFP and my fitbit to the best of their abilities so I wanted to clear my confusion up.
Thanks for any help!

Replies

  • levitateme
    levitateme Posts: 999 Member
    Personally, I don't trust calorie burn estimates that are not measured through heart rate. Even then it is only really accurate for steady state cardio. If you have a fit bit that calculate burns using your height, weight and age, expect them to be grossly inflated.
  • itsbasschick
    itsbasschick Posts: 1,584 Member
    i believe the fitbit uses BMI. when i first got my fitbit, i was over 40% body fat, and BMI uses an average - it figured me 10% lower, which meant i was a full 25% more body fat than it figured... which meant it under-calculated my burn. but hey, it tracks steps and is cute ;-) keep in mind that if you have a flex, it's going to count your arm gestures, which will inflate your daily steps, sometimes quite a bit.

    the fitbit does its best, but without a heart rate AND a good algorithm, it can only be general. a device that asks for body fat (if one even knows it) or does a fitness test (like the polar FT60) would probably be more accurate, and there are a couple activity trackers that do read heart rate.

    but ultimately to a degree, most devices are only going to give general numbers, which can still be useful.
  • missomgitsica
    missomgitsica Posts: 496 Member
    I wouldn't trust the accuracy of calories burned unless the device is monitoring your heart rate. I have a Polar FT4 heart rate monitor and I aboslutely love it.
  • trackercasey76
    trackercasey76 Posts: 781 Member
    Most people find that while wearing both a fit bit and a HRM the burn is usually pretty close.
  • snargaluff
    snargaluff Posts: 6 Member
    OH I actually have Polar FT60 but do you guys where it constantly? am i supposed to wear it the entire day?

    I use it for cardio, and the HRMand fitbit are roughly the same, but my HRM reads a littttttle bit more.
  • WalkingAlong
    WalkingAlong Posts: 4,926 Member
    I am a 22 year old female, 5 ft. 4 inches tall, 145 lbs currently, sedentary throughout the day except when exercising.
    does that mean my BMR and metabolism is pretty much the same as another sedentary 22 yr old female of the same weight and height? Is it possible that there could be a significant difference depending on other circumstances?

    Like if I was a type 1 diabetic (which I am) could my metabolism be lower than a normal person and therefore my calories burned is lower, aka my fitbit is wrong for me personally? or can I trust the numbers on my fitbit device?

    I'vee just been paranoid a lot lately, and want to use MFP and my fitbit to the best of their abilities so I wanted to clear my confusion up.
    Thanks for any help!
    Yes, it uses average BMR for someone your gender, age, height and weight. You could be different than average though I don't know if diabetes would cause that.

    I trusted the numbers on my Fitbit and lost about 35 lbs. All you can do is try it and see what happens. The good thing is you don't need to know how much you burn or even estimate it. Pick a calorie level to eat at. If you lose on average .5-2 lbs/week, keep going. If not, eat more or less or move or less, depending on if you want faster or slower losses.
  • amusedmonkey
    amusedmonkey Posts: 10,330 Member
    Personally, I don't trust calorie burn estimates that are not measured through heart rate. Even then it is only really accurate for steady state cardio. If you have a fit bit that calculate burns using your height, weight and age, expect them to be grossly inflated.

    I didn't find Fitbit to be inflated. I suspect Fitbit uses basal metabolic rate as a base, not TDEE. They then calculate your TDEE from steps taken and activities logged. They don't assume sedentary then build on it, you can actually do quite a few things and still not go above sedentary level of calorie burn and would have negative calorie adjustments on MFP. I've been using it for about a week and found my weight loss pretty consistent with their predictions.
  • StaciMarie1974
    StaciMarie1974 Posts: 4,138 Member
    BMR is an estimate and based on a standard formula derived from gender, height, weight, age. So Fitbit, MFP, etc. all use the same formulas.

    Your assumed BMR is based on the expected BMR for someone w/ average metabolism and your stats. I believe that without a lot of complicated testing, there is no way to know precisely how your BMR compares to the average. If you know you have a medical condition that affects your metabolism, then you can adjust your goals accordingly.
  • cruecu
    cruecu Posts: 1 Member
    old topic but a medgem test is the cheapest and most accurate way to quickly get your bmr. Once you have that, it somewhat eliminates the need for these all-day, try to do everything trackers. Not that to hard to figure out calories burned above your bmr

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