Please help me understand

[Virgoddess]

Hi. I can't seem to wrap my brain around this, and I need help.

I have two days that I'm comparing, and the numbers don't make sense to me.

Wednesday:

4.486 steps

1,965 calories burned

3 "very active" minutes (with a burn of 70)

1 floor

Thursday:

10,168 steps

2,081 calories burned

2 "very active" minutes (with a burn of 55)

1 floor

Both days all steps were slow/casual steps. The intensity on day 2 was slightly higher, but overall still in the low category.

Please explain to me why there is only a calorie burn difference of 116 between these two days? I really don't understand.

[SunsetRunner]

My best guess would be that the difference is so small because of the lack of very active minutes in your day.

For example, just for being alive and breathing you are "burning" x amount of calories.  For myself, in a sedentary position at work for much of my day, my estimated calorie expenditure is 1,991 calories a day.  Of course that is affected by many things, but that is just an estimate.

I would find out what your normal calorie expenditure is for a typical day, because that is probably the bulk of your number of calories listed below, then it is tweaked based on your actual steps and activity for the day.

Here is a website you can go to that has a calculator for determing:

http://nutritiondata.self.com/tools/calories-burned

Good luck!

[Dominique]

One thing you may want to check is the setting for calorie estimation (enabled or disabled), under Preferences in your profile. If you are wearing your Fitbit all the time, then you would want to disable calorie estimation (I believe it is enabled by default).

[Heybales]

Do you have another app or site linked in to Fitbit, and you logged some official exercise beyond your daily steps?

That would effect the calorie count but not the steps.

Did you record a weight change between those days?

That would effect the daily BMR burn referenced in above reply.

Where was the miles seen for those steps, because that is what actually causes the calorie burn estimate?

That could be the difference between little side steps moving around but not much, and actually striding out (but still not fast enough for VAM time).

[Virgoddess]

I do know my BMR and TDEE.

Calorie estimation is disabled.

Wednesday I walked 1.87 miles. Thursday I walked 4.25 miles.

I have MyFitnessPal linked, but I didn't log any exercises on there yesterday. I wasn't really striding at all, it was a casual walk around an amusement park, and the day before was just hanging out at home, cleaning and stuff.

I wonder if I just don't understand the caloric burn of walking. It could be that MFP has given me unrealistic expectations (which is why I always cut their estimations in half).

[Rich_Laue]

For a good explanation on BMI along with a calculater lets go to Myfitnesspall

[Virgoddess]

Yes, I know what my BMI is, as well as my TDEE. I've been at this for 6 months now, and I'm 55 pounds down. I just want to understand how walking calorie burns are figured. My two example days don't make sense to me.

[Heybales]

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@Rich_Laue wrote:

For a good explanation on BMI along with a calculater lets go to Myfitnesspall

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May be typo, but some do have concepts intertwined that are different.

That is a link to BMR, not the BMI calculator - very different things.

Just in case others could get confused.

[Heybales · Accepted solution]

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@Virgoddess wrote:

Wednesday I walked 1.87 miles. Thursday I walked 4.25 miles.

I have MyFitnessPal linked, but I didn't log any exercises on there yesterday. I wasn't really striding at all, it was a casual walk around an amusement park, and the day before was just hanging out at home, cleaning and stuff.

I wonder if I just don't understand the caloric burn of walking. It could be that MFP has given me unrealistic expectations (which is why I always cut their estimations in half).

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Fitbit and MFP database both use the same study based formula for calorie burn walking and running, that's the most accurate (more than HRM in fact) entries in MFP database, and for Fitbit - if you actually did the pace specified for the time.

http://www.exrx.net/Calculators/WalkRunMETs.html

But you must know the distance you walked (steps) and the time to do it in, to pick the correct pace. Of course Fitbit can go for between paces, MFP you'd round down, unless you did inclines, in which case you'd round up.

Walking calorie burn is based on pace (so you need distance and time) and mass, and incline (which Fitbit can't do, and MFP database doesn't really have).

So Fitbit's default stride length, or your manually entered corrected one, tells Fitbit what expected impact force and hang-time/direction of change is for your mass and a step. From that it can decide if strides were longer or shorter than expected.

So revised stride length is distance, time of the strides, and there's pace. Pace and mass - calorie burn.

So if stride length isn't correct, or you walk in such a way to confuse the device (ever seen the up and down toe walkers with short stride - more impact than expected for heel to toe walkers), length is wrong and calorie burn is wrong. Or a super smooth long strider, other extreme.

So your stats for those days with distance.

Wednesday:

4.486 steps - 1.87 miles

1,965 calories burned

Thursday:

10,168 steps - 4.25 miles

2,081 calories burned

So the steps and miles seems about right, gentle slow steps at home, maybe some false steps from cleaning, more walking steps from the park.

The calorie count does seem odd, unless it saw those harder impacts on Wed and gave bigger calorie burn for it, like jumping would give. Since it is a 3-axis accelerometer, it can tell forward or up and down motion and adjust accordingly for calorie burn.

I'm betting you got bigger calorie burn on Wed than true, probably less on Thu than true.

[Rich_Laue]

Go to your activity log to see exactly when your active minutes were counted.

Have a look at the Online Help article on this subject.

It boils down to Gender / Weight / Speed, the heavier the person is the more calories they will burn, or the faster they walk the more calories they will burn.

I don't know any other way of explainning this.

Your two examples tell me:

• You are not walking very fast
• You are walking just a little below your active minute threshold

For a minute to be active you have to have XX steps per minute.

Remember as far as Fitbit is concerned that minute starts at the 0 second count. If your step count is good from 2:15 to 3:20 seconds then you slowed down at 3:30 seconds you did not get an active minute.

[Virgoddess]

Thank you. This was very helpful.

[LewWagner]

Dominique and Heybales,

If I disable estimation of calories in settings, will I have to manually log all  my activity and somehow guess what the calories are for each activity?

What exactly is the impact of disabling calorie estimation?

[LewWagner]

D & H,

Disregard.

Checked the help info about calorie estimation and will try it for a week with the feature disabled and see what difference there is.  I don't do anything but sync my Zip several times a day.  I don't manually enter in any activities (unless on those very rare occasions where my Zip battery dies or I forget to carry it).

[Heybales]

Well, still useful info.

If everyday was about exactly the same, and you wanted a decent estimate of how your eating goal would look for the day right at breakfast, and you don't sync until late at night, or you were prone to forgetting to wear the device - then calorie estimate might be useful.

So with it enabled, look at historical data for your average daily burn, assume today will be the same, and divide that in to each hour. Say 2880. And you have 500 cal deficit.

So you wake up at 6 am, you have an estimated burn already of 720, and eating goal of 2380.

But if near end of day you finally sync and you burned only 2500, and you already ate 2380, your new goal would be 2000, and you just overate by 380 cal.

With it disabled, assume the day will be sedentary (BMR x 1.2 about) say 2200, and base eating goal on that. Say 1700. Then as day progress and you sync more activity from reality, daily burn and eating goal go up correctly.

But if near end of day you finally sync and you burned 2500, and you are done eating 1700 and bed time and now goal would really be 2000, so underate by 300 cal.

So depends on how frequently you sync, how close are your days, how tied are you to the calorie goal to change your planned eating (300 cal lunch or 400 cal?).

Until I type it out here, I never thought about all the folks that could indeed fit in one of those boxes of never syncing until night, and I'm thinking it would be easier to undereat than overeat.