Fitbit overestimating daily calories?

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  • DianeinCA
    DianeinCA Posts: 307 Member
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    TL/DR - trust the FitBit, eat more food.

    ^^^^^ THIS

    When I switched from trying to figure out net calories vs TDEE - 20% vs less 500 a day to "eat what the Fitbit tells me to for this day," I started losing regularly.
  • WalkingAlong
    WalkingAlong Posts: 4,926 Member
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    For me, and we may have dissimilar BMR, I would 'sanity check' it like this: 32000 steps minus say 2000 for sedentary = 30,000. Divide by around 2000 steps/mile = around 15 miles of 'activity'. Times 100 calories/mile = 1500 calories above BMR * sedentary rate. For me that would be around 3000, I think. So it sounds feasible. But my BMR is only in the 1300s, so 1500 for a sedentary day isn't crazy. :smile:
  • Losingthedamnweight
    Losingthedamnweight Posts: 535 Member
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    Dude...DUDE! You do about as many steps in 1 day as i do in 3-4! And you think you're lightly active? That right there shows a real lack of understanding about how all this works. "lightly" active is, at the very least, under 5,000 steps. You're what...6 times that? Uhhhhh yeahhhhhhh

    So you're a mega-stepper. And mega steppers burn tons of calories so if fitbit is telling you you're burning a few thousand calories, believe it. I've spent the past year experimenting with my fitbits questioning "is it giving me the right numbers? Does this make sense?" out of my OCD paranoia and need to have everything be just right. I've had the ONE and now the flex and my conclusion: Fitbit is ridiculously accurate for step related activities, so save yourself the trouble and just trust it.

    And now i have a goal. To beat you in steps! I think the most i've ever gotten in a single day was something like 17,000. Now i feel like a wimp
  • willrun4bagels
    willrun4bagels Posts: 838 Member
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    The Fitbit calculates the total calories you'd burn in a day, including those just for existing. If you calculate your TDEE, the numbers should be similar.

    I know that part (unlike apparently everyone on the Fitbit forums, which is why I posted here instead :smile: ) But I'm pretty sure my TDEE is closer to the low 2,000s (1,900 for lightly active, plus about 300-400/day average for running).
    You aren't lightly active. I would use very active or even extra active on the day you had two runs!

    I'm wondering about this. I add my runs separately because they vary from day to day and figure I'm lightly active when you don't count those, but I've definitely been walking more since I got the Fitbit (yay!). My (unfortunately extensive) experience counting calories and losing weight puts me at 1,900-2,000 to maintain without exercise, but maybe I've just been that much more active than usual the past few days? I'll gladly eat 3,000 Cals if I can! :love:

    OP, I haven't read through all of the rest of the comments yet, and maybe I have misread something, but this is what I have understood so far:

    -Your BMR has been calculated by you using a website to be around 1900 calories a day.
    -You have calculated your TDEE on a website to be in the low 2,000s (TDEE being BMR plus all of the movement you do aside from just existing).
    -Your Fitbit is telling you that you have burned 2200-3000 cals, depending on your exercise for that particular day (running vs. not running as much, etc.).

    From those 3 points, the Fitbit seems to be calculating your caloric burn for the day pretty accurately. I think perhaps you have underestimated your activity or workout level on the TDEE calculator. I would say you are definitely more than lightly active.

    Try recalculating your TDEE on iifym.com (I find this to be more accurate based on my numbers), and select a higher activity level.
  • Kevalicious99
    Kevalicious99 Posts: 1,131 Member
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    You have to understand ... that "These things are just estimations".

    Same with those online calculators. They are math calculations bases on the typical person of your stats. They will not always be accurate.

    The Fitbit ... which sits on my desk due to the dreaded Fitbit rash, is just that .. a toy that tried to figure out your burns based on your stats.

    BMR * 1.2 = sedentary TDEE. This increases up to 1.9x for very active.

    But they are still just estimates ... unless you are in a lab you are just guessing.

    So .. do what I do, ignore it but my Fitbit I think is pretty close for me.
  • D_squareG
    D_squareG Posts: 361 Member
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    The Fitbit calculates the total calories you'd burn in a day, including those just for existing. If you calculate your TDEE, the numbers should be similar.

    I've found this to be true. It is fairly accurate for me.
  • Losingthedamnweight
    Losingthedamnweight Posts: 535 Member
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    The Fitbit ... which sits on my desk due to the dreaded Fitbit rash, is just that .. a toy that tried to figure out your burns based on your stats.


    Then why didn't you return it and get the flex or something? Fitbit offered refunds to everyone that wanted to return their force
  • Francl27
    Francl27 Posts: 26,371 Member
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    Lightly active... seriously? Lightly active is 8000 steps a day, probably less...
  • WalkingAlong
    WalkingAlong Posts: 4,926 Member
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    I think she figured 1900ish was 'lightly active' so with her running maybe 2400 (not 3000).
  • ekat120
    ekat120 Posts: 407 Member
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    For me, and we may have dissimilar BMR, I would 'sanity check' it like this: 32000 steps minus say 2000 for sedentary = 30,000. Divide by around 2000 steps/mile = around 15 miles of 'activity'. Times 100 calories/mile = 1500 calories above BMR * sedentary rate. For me that would be around 3000, I think. So it sounds feasible. But my BMR is only in the 1300s, so 1500 for a sedentary day isn't crazy. :smile:

    That makes sense.
    So you're a mega-stepper. And mega steppers burn tons of calories so if fitbit is telling you you're burning a few thousand calories, believe it. I've spent the past year experimenting with my fitbits questioning "is it giving me the right numbers? Does this make sense?" out of my OCD paranoia and need to have everything be just right. I've had the ONE and now the flex and my conclusion: Fitbit is ridiculously accurate for step related activities, so save yourself the trouble and just trust it.

    This is me--OCD and wanting everything calculated out just right! And a mega data junkie.
    OP, I haven't read through all of the rest of the comments yet, and maybe I have misread something, but this is what I have understood so far:

    -Your BMR has been calculated by you using a website to be around 1900 calories a day.
    -You have calculated your TDEE on a website to be in the low 2,000s (TDEE being BMR plus all of the movement you do aside from just existing).
    -Your Fitbit is telling you that you have burned 2200-3000 cals, depending on your exercise for that particular day (running vs. not running as much, etc.).

    From those 3 points, the Fitbit seems to be calculating your caloric burn for the day pretty accurately. I think perhaps you have underestimated your activity or workout level on the TDEE calculator. I would say you are definitely more than lightly active.

    Try recalculating your TDEE on iifym.com (I find this to be more accurate based on my numbers), and select a higher activity level.

    I meant my BMR+NEAT(+maybe something else I'm forgetting that plays into TDEE?) was about 1900. Then a few hundred for exercise for a TDEE in the low 2,000s. The Fitbit is giving me closer to 2,500 for a "typical" day (2,200 without formal exercise). I think it's pretty accurate for BMR, but it's the NEAT (non-exercise activity thermogenesis) that seemed high.

    I'm glad to hear that it's been accurate for others. I don't consider myself to have a low metabolism, so if it's accurate for others I'd imagine it is for me, too. I guess I'm just more active than I thought (and have been making a somewhat concerted effort to walk more consistently since I've been wearing it, though I've always walked quite a bit). I guess if I'm delusional at least it's in the "right" direction :laugh:
  • WaynesGurl
    WaynesGurl Posts: 44 Member
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    32,000 steps would put me at about 18 miles.

    11000 steps gave me just over 5 miles...?
  • shadow2soul
    shadow2soul Posts: 7,692 Member
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    I've seen this guideline tossed around (and, comparing my Fitbit TDEEs to the various charts, it seems dead on for me)

    Sedentary = <5000 step

    Low Active = 5000-7499 steps

    Somewhat Active = 7500-9999 step

    Active = 10000-12499 steps

    Highly Active = 12500+ steps

    And you think 32,000 steps is lightly active? :huh: Even if you back out 6 miles of running, that's maybe only 12,000 or so (give or take) of your steps, leaving you 20,000 of general activity....

    ^ Seriously this.

    I've been using fitbit since last year. It definitely underestimates calorie burns for me and as such I trust it 100%.
  • MomTo3Lovez
    MomTo3Lovez Posts: 800 Member
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    Well I am glad I decided to read this thread as I have a fitbit flex as well and according to fitbit I have been under eating which I have been using calories based off of my TDEE - 20% and gave me 1650 and even when I got close to that at the end of the day it still had me at being under my calories. So I will try going by fitbit and see what happens.
  • DianeinCA
    DianeinCA Posts: 307 Member
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    32,000 steps would put me at about 18 miles.

    11000 steps gave me just over 5 miles...?

    Yesterday I did 40k steps and Fitbit said that was about 18.41 miles.

    I find that walking a mile is about 2300 steps and running a mile is about 2100 steps. For me and my stride. Obviously, everyone differs!
  • ekat120
    ekat120 Posts: 407 Member
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    40k! Super impressive!!!
  • WBB55
    WBB55 Posts: 4,131 Member
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    The Fitbit is giving me closer to 2,500 for a "typical" day (2,200 without formal exercise). I think it's pretty accurate for BMR, but it's the NEAT (non-exercise activity thermogenesis) that seemed high.

    Did you mention? Is this the One or the Flex? And wear do you wear it? If it's kinda giving you too much burn during your non-structured exercise time, you could wear it in a different spot when you're not exercising. Like if it's the one, try moving it from your bra to your waist. Or if it's the Flex, switch to the other arm or change the setting where it says non-dominant to dominant. Just something to try.
  • willrun4bagels
    willrun4bagels Posts: 838 Member
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    32,000 steps would put me at about 18 miles.

    11000 steps gave me just over 5 miles...?

    Yesterday I did 40k steps and Fitbit said that was about 18.41 miles.

    I find that walking a mile is about 2300 steps and running a mile is about 2100 steps. For me and my stride. Obviously, everyone differs!

    40k steps?!?! You need some sort of medal.
  • WinoGelato
    WinoGelato Posts: 13,454 Member
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    Also OP, just thought of this since you said you are pretty OCD when it comes to the numbers...

    Do you have negative adjustments enabled? I find that to be helpful also, for days I am less active, so if I really don't achieve the expected TDEE goal, MFP takes away some calories too. I think that helps ensure accuracy on more sedentary days.
  • RHachicho
    RHachicho Posts: 1,115 Member
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    They are just estimations. There is so much a titbit doesn't know about what you are doing. That said So far mine doesn't seem too far off the mark. Though I have had it less than a week. I am recording my daily deficit according to it though and I am going to compare it to my weight loss over a period. That's definitely the best way to gauge how accurate it is for you.

    Honestly though it doesn't sound like you actually eat as much as you could or should for your level of activity. I am just getting into running myself and as someone who isn't used to it it's hard! It sounds like you are very used to it though so it may feel like you aren't really burning that much when really your body has been working hard.
  • ekat120
    ekat120 Posts: 407 Member
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    Also OP, just thought of this since you said you are pretty OCD when it comes to the numbers...

    Do you have negative adjustments enabled? I find that to be helpful also, for days I am less active, so if I really don't achieve the expected TDEE goal, MFP takes away some calories too. I think that helps ensure accuracy on more sedentary days.

    I'm just tracking on their website (not really a fan of the MFP food diary). It's definitely motivating to see how much less it gives me when I'm less active!
    Honestly though it doesn't sound like you actually eat as much as you could or should for your level of activity. I am just getting into running myself and as someone who isn't used to it it's hard! It sounds like you are very used to it though so it may feel like you aren't really burning that much when really your body has been working hard.

    I feel like I eat a lot (been netting around 1,800, which I guess isn't *that* much), but I think you might be right. I never thought of myself as someone who wasn't eating enough! I will happily eat more and see what happens.

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