Fitbit adjustments seem arbitrary

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jenneefur
jenneefur Posts: 3 Member
in Fitness and Exercise
Hi! I've been using both MFP and Fitbit for a while now and have seen good results (when I'm consistent!). I usually eat 12-1500 calories a day, but I've noticed that my fitbit adjustments seem a little all over the map. For example, yesterday I ended the day at 12,669 steps but only got 88 calories back. Today, as of 8:50 AMI've done 3,559 steps but got 181 calories back. Does this make sense to anyone?

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  • shadow2soul
    shadow2soul Posts: 7,692 Member
    edited June 2015
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    It has nothing to do with steps.
    Fitbit sends over the current calorie burn at whatever time you synced it last. We can use my numbers for an example. 599 @ 8:14 am
    MFP expects that I should burn 1907 by the end of the day. That's equal to 79.458 calories per hour or 1.3243 per minute.
    MFP then calculates a new expected burn from what I've burned already from my Fitbit.
    My day (as of last sync) has 15 hours 46 mins left.
    15 * 79.458 = 1191.87
    46 * 1.3243 = 60.9178
    599 + 1191.87 + 60.9178 = 1851.7878
    So MFP is expecting that based on my last sync, my Fitbit will report a burn of 1851 at 11:59 pm tonight. I'm currently losing calories, but I will get more as the day goes on.

    These numbers are recalculated every time you sync your Fitbit (or shortly after at least). So say you get up in the morning and go workout; your calorie burn for that time frame is probably higher per min/hour than it will be at other times during the day and you end up with a large adjustment at first. Then you go to work and sit at a desk for several hours; thus lowering your calorie burn per min/hour to lower than MFP's expectation and you lose some of the adjustment you were originally given.

    I hope that's not too confusing of an explanation. The simple explanation is your adjustment is a comparison of your Fitbit calorie burn and your MFP calorie burn.
  • jenneefur
    jenneefur Posts: 3 Member
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    No that makes perfect sense! Thank you!
  • editorgrrl
    editorgrrl Posts: 7,060 Member
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    jenneefur wrote: »
    Hi! I've been using both MFP and Fitbit for a while now and have seen good results (when I'm consistent!). I usually eat 12-1500 calories a day, but I've noticed that my fitbit adjustments seem a little all over the map. For example, yesterday I ended the day at 12,669 steps but only got 88 calories back. Today, as of 8:50 AMI've done 3,559 steps but got 181 calories back. Does this make sense to anyone?

    Click on any adjustment to see the math MFP used to calculate it.

    Your Fitbit burn is TDEE (total daily energy expenditure), the number of calories necessary to maintain your current weight. Your default MFP calorie goal is activity level minus deficit. Adjustments are the difference between your Fitbit burn and your MFP activity level.

    If (and only if) you enable negative calories adjustments in your diary settings, eating back your adjustments means you're eating TDEE minus deficit.

    You can learn more in the Fitbit Users group: http://community.myfitnesspal.com/en/group/1290-fitbit-users

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