Negative calorie adjustments.

What is the consensus ..for or against enabling this feature? I'm using a Fitbit.

Replies

  • kathrynjean_
    kathrynjean_ Posts: 428 Member
    If you're using Fitbit and have your accounts synced, you should definitely have this feature enabled.
  • editorgrrl
    editorgrrl Posts: 7,060 Member
    With negative calorie adjustments disabled, you'll never eat at a true deficit on days you burn fewer calories than your MFP activity level. (But they'll never put your calories below 1,200.)

    You can learn more in the Fitbit Users group: http://community.myfitnesspal.com/en/group/1290-fitbit-users
  • LAT1963
    LAT1963 Posts: 1,375 Member
    edited September 2015
    Here's what I've only recently figured out from using my Polar A300 (which includes activity monitor).

    When you exercise, mfp time-based estimates and exercise trackers like runkeeper and endomondo give you the total calories expended during your exercise. Lets say you do 2 hours for a total of 600 calories of an activity. This total for the 2 hours of activity is a measurement of your baseline metabolic rate (BMR) + calories burned from moving around.

    The MFP daily target is your BMR + estimate of calories burned from moving around as based on the category you gave yourself to describe your activity level - target deficit to lose weight at the desired weekly rate. Lets say your BMR + estimate of baseline calories is 2000 calories, and your target deficit is 500 calories, so you daily calorie target estimate is 1500 calories.

    Since MFP estimates BMR + baseline = 2000 calories as maintenance, that means during your normal day with typical activities, you burn the MFP estimate/24 hours = 83.3 calories/hour. This is how much MFP thinks you burn per hour when there are no deliberate deficits going on. This is how fast you are burning calories as you do your normal daily activities without a concerted effort to exercise more.


    If you take your MFP target and add additional exercise calories reported by mfp or runkeeper, you get:

    From MFP baseline estimate for 24 hours:

    BMR(24 hr) + reported baseline activity level(24 hr) - target deficit(24 hr)
    =1500 calories


    From runkeeper (endomondo, etc) for duration of exercise:

    BMR(2 hr) + actual activity level(2 hr)
    =600 calories


    Adding those together you get:

    BMR(24 hr) + reported baseline activity level(24 hr) - target deficit (24 hr)
    + BMR(2 hr)+ actual activity level(2 hr)
    =2100 calories


    So you would think that you should be able to eat 2100 calories that day--but you can't.

    The problem here is that when you add the measured activity calories (which already includes BMR) you double-count your BMR and baseline activity level for the duration of the exercise. Rather than add the activity calories, you need to substitute the measured activity calories for the MFP baseline estimate for the same length of time.


    What you need is:

    BMR(24 hr) + reported baseline activity level(24 hr) - target deficit (24 hr) (MFP daily estimate)

    + BMR(2 hr)+ actual activity level(2 hr) (calories measured from activity including BMR & baseline activity)

    -BMR(2 hr) -reported baseline activity level(2hr)
    (because you are replacing these 2 hours of estimated calories with the ones included in your measured 2-hour "actual activity")


    Plugging in my example numbers:

    1500 calories (MFP target including deficit)
    +600 calories (from runkeeper, endomondo, MFP lookup-table, activity monitor)
    -2hrs * 83.3 calories/hour ("negative calorie adjustment" to correct for double-counting)

    = 1934 calories target.


    You can also get a negative calorie adjustment if your measured actual activity for the day is less than the MFP expected estimate based on the typical-day activity category you gave yourself. So, if MFP expected you to burn 2000 calories, but your activity monitor measured your activity all day as 1900 calories (100 calories less than expected), then your MFP target estimate with deficit was 1500, but gets a -100 calorie adjustment to 1400 calories based on the real data. This can give you a nasty surprise at the end of the day when you think you have 40 calories left, sync your monitor, and suddenly wind up 60 calories over your newly-adjusted target!
  • alfonsinarosinsky
    alfonsinarosinsky Posts: 198 Member
    editorgrrl wrote: »
    With negative calorie adjustments disabled, you'll never eat at a true deficit on days you burn fewer calories than your MFP activity level. (But they'll never put your calories below 1,200.)

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

    Thank you so much. I don't completely understand it. They should have a Fitbit/Mfp handbook for dummies lol
  • alfonsinarosinsky
    alfonsinarosinsky Posts: 198 Member
    LAT1963 wrote: »
    Here's what I've only recently figured out from using my Polar A300 (which includes activity monitor).

    When you exercise, mfp time-based estimates and exercise trackers like runkeeper and endomondo give you the total calories expended during your exercise. Lets say you do 2 hours for a total of 600 calories of an activity. This total for the 2 hours of activity is a measurement of your baseline metabolic rate (BMR) + calories burned from moving around.

    The MFP daily target is your BMR + estimate of calories burned from moving around as based on the category you gave yourself to describe your activity level - target deficit to lose weight at the desired weekly rate. Lets say your BMR + estimate of baseline calories is 2000 calories, and your target deficit is 500 calories, so you daily calorie target estimate is 1500 calories.

    Since MFP estimates BMR + baseline = 2000 calories as maintenance, that means during your normal day with typical activities, you burn the MFP estimate/24 hours = 83.3 calories/hour. This is how much MFP thinks you burn per hour when there are no deliberate deficits going on. This is how fast you are burning calories as you do your normal daily activities without a concerted effort to exercise more.


    If you take your MFP target and add additional exercise calories reported by mfp or runkeeper, you get:

    From MFP baseline estimate for 24 hours:

    BMR(24 hr) + reported baseline activity level(24 hr) - target deficit(24 hr)
    =1500 calories


    From runkeeper (endomondo, etc) for duration of exercise:

    BMR(2 hr) + actual activity level(2 hr)
    =600 calories


    Adding those together you get:

    BMR(24 hr) + reported baseline activity level(24 hr) - target deficit (24 hr)
    + BMR(2 hr)+ actual activity level(2 hr)
    =2100 calories


    So you would think that you should be able to eat 2100 calories that day--but you can't.

    The problem here is that when you add the measured activity calories (which already includes BMR) you double-count your BMR and baseline activity level for the duration of the exercise. Rather than add the activity calories, you need to substitute the measured activity calories for the MFP baseline estimate for the same length of time.


    What you need is:

    BMR(24 hr) + reported baseline activity level(24 hr) - target deficit (24 hr) (MFP daily estimate)

    + BMR(2 hr)+ actual activity level(2 hr) (calories measured from activity including BMR & baseline activity)

    -BMR(2 hr) -reported baseline activity level(2hr)
    (because you are replacing these 2 hours of estimated calories with the ones included in your measured 2-hour "actual activity")


    Plugging in my example numbers:

    1500 calories (MFP target including deficit)
    +600 calories (from runkeeper, endomondo, MFP lookup-table, activity monitor)
    -2hrs * 83.3 calories/hour ("negative calorie adjustment" to correct for double-counting)

    = 1934 calories target.


    You can also get a negative calorie adjustment if your measured actual activity for the day is less than the MFP expected estimate based on the typical-day activity category you gave yourself. So, if MFP expected you to burn 2000 calories, but your activity monitor measured your activity all day as 1900 calories (100 calories less than expected), then your MFP target estimate with deficit was 1500, but gets a -100 calorie adjustment to 1400 calories based on the real data. This can give you a nasty surprise at the end of the day when you think you have 40 calories left, sync your monitor, and suddenly wind up 60 calories over your newly-adjusted target!

    Thank you so much. I'm going to read this very carefully in order to wrap my brain around it.

  • editorgrrl
    editorgrrl Posts: 7,060 Member
    I learned so much from the Fitbit Users group—that's why I tell everybody about it. And keep asking questions!
  • alfonsinarosinsky
    alfonsinarosinsky Posts: 198 Member
    editorgrrl wrote: »
    I learned so much from the Fitbit Users group—that's why I tell everybody about it. And keep asking questions!

    Thanks!!!
  • LAT1963
    LAT1963 Posts: 1,375 Member
    edited September 2015
    Another way to put my long post:

    Based on what you said about your activity, MFP estimates how many calories your metabolism burns in 24 hours.

    If you measure what you burned for 2 of those 24 hours, you have to replace the MFP-estimated burn for those 2 hours with the measured burn for those 2 hours, not just add the measured burn on.

    If you don't subtract the 2 hours of MFP estimate with a 'negative adjustment', its like saying you had a 26 hour day--the 24 hours of burn estimated by MFP plus the 2 hours of measured burn.

  • robertw486
    robertw486 Posts: 2,379 Member
    LAT1963 wrote: »
    Another way to put my long post:

    Based on what you said about your activity, MFP estimates how many calories your metabolism burns in 24 hours.

    If you measure what you burned for 2 of those 24 hours, you have to replace the MFP-estimated burn for those 2 hours with the measured burn for those 2 hours, not just add the measured burn on.

    If you don't subtract the 2 hours of MFP estimate with a 'negative adjustment', its like saying you had a 26 hour day--the 24 hours of burn estimated by MFP plus the 2 hours of measured burn.

    I'm trying to come to grips with the deficiencies in the various apps, methods, calculators, etc as far as exercise goes. It sure would be a lot easier if someone made an app with more features that could be user altered.

  • redperphexion
    redperphexion Posts: 193 Member
    But if you log a timed exercise in MFP, it automatically takes your MFP burn + BMR and replaces the FitBit data.... right?
  • StaciMarie1974
    StaciMarie1974 Posts: 4,138 Member
    If you normally get extra calories from your Fitbit activity: negative calories is not really an issue.
    If you normally see a 0 calorie adjustment from Fitbit, then you may be eating too much.

    MFP estimates your daily burn based on your stated activity level. If you say you're lightly active, then MFP thinks you should burn X calories per day. Fitbit estimates your daily burn based on your actual activity. If Fitbit's actual # is lower than X you would see a negative adjustment (if enabled) or 0. Using the negative adjustment means MFP would lower your daily calorie intake goal if you are having a lower activity day.