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Active calories

topcaser
over 4 years ago

Hi,

the watchface infoCal can show active calories. Active calories are not given directly in the activity.info class. It (the feature) is titled in the settings as experimental so the developer found probably a way to reverse calculate it from some other fields.

Any hints how? 

I tried to use active daily minutes to get a ratio of minutes gone on a day to that active daily minutes and apply this ratio to the calories. But it don't currently works. The reverse formula was:

active calories = calories * active daily minutes / minutes of the day

Today I have at 9:30 am 9 active calories yet, but active daily minutes is 0. But my step count is at 436. By observation the active daily minutes is obviously not the only factor for active calories.

Another formula try could be:

active calories = calories * active daily minutes / minutes of the day + step count / 50

What do you think?

  • over 4 years ago

    Hi

    search on google

    Mifflin-St.Jeor Formula (1990)
    It's a formula for BMR on 24hours
    After you can calculate difference between calories and this formula for the time of the day.
    Didier
  • over 4 years ago in reply to riedid74

    Hm, thanks for this. I used this equation:

    BMR = 66.47 + ( 6.24 × weight in pounds ) + ( 12.7 × height in inches ) − ( 6.755 × age in years )

    and calculated the BMR to be 1563 kCal for myself. At 9:30 today we have a ratio to the entire day of 0,3958.

    0,3958 * 1563 kCal is 619 kcal for the base calories consumption. At this time my watch showed 760 rest calories and 9 active calories.

  • over 4 years ago in reply to topcaser

    Yep none of the standard BMR formulae seem to match what Garmin uses, but I believe it does fit the form: k + x*age + y*height + z*weight = cal (forums.garmin.com/.../active-calories-available-yet)

    I plan to calculate the constants soon* - but it's not risen to the top of my "to do" list yet Slight smile

  • over 4 years ago in reply to markdotai

    I seem to recall that Garmin adds to basic BMR cals, with something like adding on a percent.

    The reason being is you burn more calories if you're standing vs lying down, even if you're doing nothing more.

  • over 4 years ago in reply to jim_m_58

    Ahh yep, there is a standard factor of 1.2 as well for that - but still seems different from any standard BMR formula I can find.

    's example of 619 would go to 743 (instead of 760)

  • over 4 years ago in reply to markdotai

    Ok I had to go and do some further proper calculations Slight smile This is the formula I've come up with so far (for a male):

    Garmin 24 hour resting calories = 5.0 - 6.12*age + 7.63*height + 12.2*weight

    Age in whole years, height in cm, weight in kg

    From my tests if you round that value to the nearest integer then it is within +-1 of the resting calories displayed on my watch (Fenix 5X+) - it's possible it could be different on different devices … or that the formula could be changed in the future etc ...

    Would be nice to improve it so it's exactly the same integer value.

    And I'll work out the female formula too later.

  • over 4 years ago in reply to markdotai

    Actually that formula above is really close to the versions of Mifflin-St.Jeor when multiplied by the 1.2:

    (5 - 4.92*age + 6.25*height + 9.99*weight) * 1.2 == 6 - 5.9*age + 7.5*height + 11.99*weight

    or

    (5 - 5*age + 6.25*height + 10*weight) * 1.2 == 6 - 6*age + 7.5*height + 12*weight

  • over 4 years ago in reply to markdotai

    Hi,

    I put my values in your formula and the result is way off e. g. for @15:53 -> the watch showed: 1255 kCal, your formula evaluates to 1895 kCal :-(

  • over 4 years ago in reply to topcaser

    Ah, but you need to multiply by the percentage of the day like in your previous post.

    So 15:53 is 15*60+53 = 953 minutes into the day and 24 hours is 1440 minutes.

    So 1895 * 953 / 1440 = 1254.12

    Rounded to the nearest integer gives 1254

    Close to 1255, but still 1 out Slight smile

    Would be nice to get it perfect ...

  • over 4 years ago in reply to markdotai

    Arrrgh, this was my mistake. Sorry, you are right, if fits almost perfectly. I think, it's good enough. Saying this, which formula do you recommend now? You posted 3, although the last two are very similar.