Fit bit calories Do I trust it????



  • marilyndawn77
    marilyndawn77 Posts: 3 Member
    I agree & trust my FitBit for all activity calories. Don't log any from the MFP.
  • auddii
    auddii Posts: 15,357 Member
    I use a fitbit (the flex) because it motivates me to move more (I like getting lots of steps and beating either friends or myself).

    I also have spent several months very accurately tracking intake and how much I lost. I do exercise that the fitbit doesn't log well like weight lifting; I also do exercise that it does log the steps right like using the elliptical. I also have had it hit 10,000 steps when driving and when washing my face in the shower.

    However, it appears that what it under counts and what it over counts is pretty much a wash. Accurately tracking, I found my TDEE is about 2800 calories. A 30 day average of my fitbit says I burn about 2800 calories per day. So...
  • PAV8888
    PAV8888 Posts: 11,433 Member
    edited May 2015
    Does the Fitbit Charge HR add random steps or subtract random steps... randomly? Absolutely.

    Does it still manage to accurately calculate most people's TDEE? Based on posts and my own experience. YES.

    Do you still have to evaluate over time how well it works/continuous to work for you? Absolutely.

    After using the Charge HR for a few months now, I have decided to introduce a 5% adjustment to the TDEE it indicates.

    In other words I will be subtracting my deficit from 95% of my Fitbit TDEE as opposed to the 100% I previously used. This could be because of Fitbit's calculations, or my own adaptation, or my own logging. Regardless, the results argue that I am expending about 95% of what Fitbit thinks I am.

    To the OP. You probably got an exercise adjustment and are wondering what % to eat.

    Click on the info icon of the adjustment and look at the Fitbit TDEE used in the calculation.

    Check the time.

    The calculation is based on you continuing to be active at the same rate you've been so far till midnight.

    If you don't continue to be so, the Fitbit TDEE will reduce as time goes on.

    Then go ahead and assume that the TDEE number is mostly correct (subject to the time adjustment and maybe an extra 10% factor to be conservative---i am only using 5%/personally) and decide what % of the remaining you feel comfortable eating.

    BTW. If all this "burn" was generated by extra or new exercise, regardless of whether you eat more or not, you will probably weight more over the next few days due to your muscles retaining water to repair themselves. So on a one time basis you will not be able to know if your Fitbit was accurate.

    But if you have your Fitbit for a month, comparing your actual results to what it says should allow you to form your own opinion as to its accuracy.

    (and use something like to average out the noise that is introduced by daily scale fluctuations)
  • shadow2soul
    shadow2soul Posts: 7,693 Member
    Yes I trust mine. I've had mine for awhile. The Zip and Flex models were under by about 200 calories on average (I had each for approx 10 months). I am currently using the Surge and it seems to be spot on.

    I'm a little shorter at 5'4.5". I'm approximately 140lbs right now. I average just under 10,000 steps a day.
    Current 30 Day average Burn: 2548
    Current 30 Day average Intake: 1936
    Expected 30 Day loss: 5.2xxxx lbs
    Actual 30 Day Scale loss: 5.4 lbs
    ^That works out to be pretty darn accurate for me. However, I can't guarantee that everyone will have the same results. Some people have discovered after 4-6 weeks careful logging (weigh food when possible/ect) that Fitbit was up to 10% to high. Even if you discover it estimates too high, you can use that information to your advantage to find what is actually a safe number to eat.

  • PAV8888
    PAV8888 Posts: 11,433 Member
    edited May 2015
    shell1005 wrote: »
    I use my fitbit and use my brain! GO ME!
    I also don't assume the calorie burn they state is accurate. I agree with the rough estimate of counting about half of what they say. The other thing I have been doing since I synced my fitbit with MFP...when I add in either running or treadmill or elliptical, etc....I take the calorie counter out since fitbit is already counting it, etc.

    So you count half of the Fitbit's TDEE?
    Or you count half of the exercise adjustment?
    And is your activity setting setup correctly in MFP?
    Because the concept of exercise adjustment if your activity setting is incorrect...

    In reality there is no exercise adjustment.
    Fitbit is making a guess as to your TDEE.
    It is called exercise adjustment for convenience; but it doesn't really represent exercise.

    Exercise "eat back" rules don't quite apply to TDEE
  • WaterBunnie
    WaterBunnie Posts: 1,372 Member
    I have the FitBit One and generally eat back all my exercise and still lose but a friend of mine (of similar weight) has the Charge HR and sometimes gets 3 times as many exercise calories for a lower mileage. This has put me off upgrading because it's the adjustment here I bought it for.
  • jeanners98
    jeanners98 Posts: 74 Member
    Hey this seems right... It basically means you burned all your calories the body usually burns by resting (for me that's usually 2200ish (and I'm 5'5 160) THEN you earned an additional 1000+ calories from working out. If you did take 23000 steps then yes, this seems perfectly right. I've had days where I run and go for a long walk, get to that amount of steps, and get about 1000 calories added. I don't usually eat them all because that's a lot of food, but no judgement and eat what you want! I find the fitbit super accurate,
  • FoxyLifter
    FoxyLifter Posts: 965 Member
    edited May 2015
    1) Trial and error is your friend. See what happens after a month or so to your weight and inches.

    2) I wouldn't rely too heavily on calorie burn trackers. I used to use one, but my calories burned were pretty from week to week so I saw no need for it.

    3) Make sure your calories IN are in check. Be sure to weigh all of your solids with a food scale and choose the correct database entries. If these measurements are off, you won't be able to tell if your Fitbit is close or way off.

    ETA: when I entered in my calories burned from my HRM, I would add back in 75-80% of the calories just to be safe (I like to eat as close to goal as I can). When I entered in an activity using the MFP database, I would add it in with half the time. For example, If I walked around the park for an hour, I would log 30min. One hour of walking would give me 400 calories and a half hour would give me 200. I would add the 30min/200 calories and add that to my normal "no exercise" calorie goal (1700) for a total of 1900 calories to eat for the day (I prefer to have less than 50 calories remaining when I close my diary for the day).
  • joelschneider45066
    joelschneider45066 Posts: 76 Member
    edited May 2015
    I have had a Fitbit Charge HR since Jan and for a long time I did double measurements. That is I wore a Polar HR chest band/watch monitor while I wore my Charge HR and did both vigorous workouts and less vigorous workouts. For me they were very close together, meaning the Charge was pretty darn close to the Polar HR. This relates to Heart Rate and the Calories Fitbit gives me back each day. Where I have found the Fitbit Charge HR not so good is when I am on the elliptical it doesn't measure steps or distance accurately. I get maybe 20-30% of actual there. I tend to get lots of calories "back" from Fitbit each day, but I am marked as "Sedentary" since I have a desk job. Most days I get between 1200 & 1500 extra calories from FitBit of which I eat most back, and I have been pretty much consistently losing 2 lbs per week. The last couple of weeks I have been mostly relying on long daily walks for my calories, averaging about 18-20K steps per day but on Monday May 11th I had a pretty active day and burned a total of 5K calories that day (according to my Charge HR) which gave me back in MFP about 2500 calories. But this was a day I had over 10 miles in steps and lots of other general activity.


  • joelschneider45066
    joelschneider45066 Posts: 76 Member
    edited May 2015
  • PAV8888
    PAV8888 Posts: 11,433 Member
    shell1005 wrote: »
    I use my fitbit and use my brain! GO ME!
    I also don't assume the calorie burn they state is accurate. I agree with the rough estimate of counting about half of what they say. The other thing I have been doing since I synced my fitbit with MFP...when I add in either running or treadmill or elliptical, etc....I take the calorie counter out since fitbit is already counting it, etc.

    So based on this post you have connected your Fitbit to MFP and are using it to calculate your burn.
    This means that you are using Fitbit's TDEE calculation and having MFP compare it to MFP's own TDEE calculation.
    MFP then shows the results of this comparison to you as a positive or negative "exercise adjustment".

    Which you then, as per the above, treat as an exercise as opposed to a TDEE adjustment, and you eat back half of your "exercise" calories (which they aren't) as opposed to eating to your chosen deficit from TDEE (or 95% or 90% adjusted TDEE if you don't feel, like I don't, that the Fitbit TDEE is 100% accurate FOR YOURSELF)

    Then you post and say:
    shell1005 wrote: »
    It's great those who use the TDEE assessment. I use the MFP calculations and exercise adjustments. I choose to eat back at most half my calories since almost all of those indicators overestimate the calorie burn IMO. Using the app as it is designed works for me. Nothing wrong with that. Thanks for your concern.

    OK. Let me know when you decide which method you're using!

    Because even though it is called an exercise adjustment, it is actually a TDEE adjustment. Therefore the "rules" of exercise being overestimated don't quite apply. And you only get the exercise adjustment IF your MFP activity level is under-estimated in the first place. Which would be pointing to a potential error in choosing your MFP activity level.

    In the meanwhile, glad it is working out for you.
  • editorgrrl
    editorgrrl Posts: 7,062 Member
    edited May 2015
    i am afraid to trust my Fitbit calorie allowance. I have a charge hr so it monitors heartrate and steps. I was very active yesterday and worked out. It says I burned 3143 calories and gave me 2100 calories to eat. I have it set at 2 lb weightloss. I am a female 5 5' 165 lbs.
    It just seems like a lot of food! Do I trust it??

    MFP has a Fitbit Users group:

    Your Fitbit burn is your TDEE (aka your maintenance calories). If you eat at a reasonable deficit from that, you will lose weight. The only way to gauge the accuracy is to trust your Fitbit for several weeks, then reevaluate your progress.

    I, too, was shocked how many calories Fitbit gave me. But I lost the weight & have maintained for ten months. Trust your Fitbit!