Why is my fitbit showing 300-400 calories during my 30m walk on the treadmill

[w7psk]

But the treadmill says 100.   I walk at 2.0 - 2.2mph 30 to 35 minutes a day. Im trying to guage my intake  vs burn but if fit but is calculating too high then Im not doing what I need.  I avg 1500-1800 cal in.

[LeahPope]

Mine starts counting calories burned at midnight everyday, so there is definitely something wrong with the tracker.  I am researching more now.  Let me know if you find anything!

[Heybales]

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@LeahPope wrote:

Mine starts counting calories burned at midnight everyday, so there is definitely something wrong with the tracker.  I am researching more now.  Let me know if you find anything!

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That would be correct - because you are burning calories every second if you are alive.

That's not an issue.

[Heybales]

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@w7psk wrote:

But the treadmill says 100.   I walk at 2.0 - 2.2mph 30 to 35 minutes a day. Im trying to guage my intake  vs burn but if fit but is calculating too high then Im not doing what I need.  I avg 1500-1800 cal in.

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So calorie burn for walking & running is most accurate using formula based on mass, distance, and time (pace).

Treadmill used that if you input your weight - did you?

Some don't and use the default weight, sometimes that is 150 lbs.

Fitbit uses that distance-based calorie burn for daily activities, until the steps and HR goes high enough it thinks you are doing a workout.

Then it switches to HR-based formula.

That formula is ONLY potentially valid during steady-state aerobic exercise, same HR, so not intervals, not anaerobic, not lifting, ect.

The farther the workout was from the best case scenario, the worse the calorie burn is inflated. And even in best case several reasons it'll lose whatever level of accuracy it even had.

The bottom and top of that aerobic range - right above daily activity, and right below going anaerobic - calculations cause inflated calorie burn.

So 3 potentials in your attempt to compare.

Treadmill was way off because you didn't input a weight.

Fitbit was off because it has bad stride-length for you, and therefore it's distance is off using same formula. (compare it's distance with treadmill sometime)

Fitbit was off because it used HR-based formula and inflated the calorie burn.

Most of those can be tweaked, or disabled (HR while walking) - to give better calorie burn estimate.

[w7psk]

Ok, I never input weight on Treadmill ... I use Planet Fitness and dont want to mess around, I just hit fast start and Go :).  I do have weight in the fit bit.  So like today I did a mix of 2.2 and 2.5 about 1/2 and 1/2.  Being 66 and way over weight ... Im trying to get cardio up as the Dr would like it I ran 28 minutes of cardio with an avg of 117 :). The treadmill said 104 and the fitbit 400 

 I've lost close to 30 pounds so far, so something is working. Although Im at a plateau right now.   

Long way to go on the weight loss.

Oh and I measured and input stride length.   Even when I walk on the waterfront for 30m the fitbit says 300 - 400 cal out.  Plus I have the Impulse HR and it uses the phone GPS to measure stride length when I walk on the waterfront so I hope its keeping that.

[Heybales · Accepted solution]

So again - you'll have to forget the treadmill if you didn't input weight.

Would you log your weight on scale if you left 1 foot on the ground and 1 on the scale?

Now - hopefully the treadmill is calibrated and pretty correct for mileage.

If you start a workout on the Fitbit when you start the treadmill, and just do 1/2 mile at start, and about 1/2 your exercise pace so you are between grocery store shuffle and exercise level pace, maybe 1.4 mph. Stop that workout when done with 1/2 on the dot. It will feel slow, but you really want a pace right in the middle.

Then do your regular workout to finish it up.

You can look later at that Activity Record and see what distance the Fitbit thought you did, compared to the 1/2 mile you know you did.

That will tell you if a tweak is needed for your stride length, that will help improve accuracy for mainly your daily walking.

Because GPS is just not that accurate, it can bounce within a 3m accuracy range IF it's at best accuracy which it may not be. Since that tends to overestimate the distance and stride length based on that - it means it thinks you are getting longer distance than reality - most likely.

And then take the results of your 1/2 mile test and used with this calculator and Gross option, will tell you if the Fitbit estimate of calories was good or not.

https://exrx.net/Calculators/WalkRunMETs

Because 300-400 for 30 min is actually pretty high intensity effort, and stroll on boardwalk doesn't sound like it. So that does sound inflated.

And to your point - if the burn side isn't correct, the eating side isn't correct.

[LeahPope]

Even so, it is difficult for me to believe that I burned 697 calories during 5 hours of sleep last night!  While I appreciate your input (and your elaborate post for the original poster), I must believe there is a legit issue.

[w7psk]

Thanks Heybales, 

Im going to adjust stride length because its off on distance. And its not a stroll on the boardwalk, I go at t brisk pace, but your right 400 is too much.  So Ill let you know how it goes after I do the test tomorrow at the gym :). 

I still keep cal down to 1500 - 1900 if I can and watch what I eat.  Hopefully I can get this adjusted to the point I can make it fit closer and keep the loss going 

[Heybales]

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@LeahPope wrote:

Even so, it is difficult for me to believe that I burned 697 calories during 5 hours of sleep last night!  While I appreciate your input (and your elaborate post for the original poster), I must believe there is a legit issue.

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Only commented because your statement sounded like a common misunderstanding of the fact we burn calories 24 hrs a day, and you provided no figures.

Many people don't realize that.

That is called your BMR when sleeping. Fitbit and other trackers use that value for ALL time they see no steps - so under-estimated calorie burn actually when awake or standing.

Fitbit uses a BMR calculation very close to Mifflin BMR, a more recent formula vast majority are within 5% of, even with thyroid issues.

Is the time on your device correct, really only 5 hrs from midnight?

697 / 5 = 139.4 cal/hr

That is rather high and very unlikely for a female.

Hence wondering if device synced at what it thought was 6 hrs (116 BMR/hr) which is still high but closer to possible. (phone syncing with device can be on 1 time zone, Fitbit account and device can be set for another).

Another thing to check because I'm guessing this is first use - is the body stats correct for age, gender, weight, height, Metric or US correct?

Fitbit had an issue awhile back where despite people looking at a figure for weight that said lbs, you could do the math and see that Fitbit failed to convert to metric for the math and just used the lbs figure as kg figure. Rather inflated values.

You had to say you were using kg, input a correct kg figure. Then say you were using imperial and put the lbs back in. Then it saved and converted it correctly for math.

Very odd bug but it got many.

For instance with that bug a 40 yr old woman @ 266 lbs and 66" tall would be given a BMR of 3349 - or 140 cal/hr.

When it should really be 1893 - or 79 cal/hr.

Might check your stats as first easy step.

[beth2c]

I am having the same issue.  I did a 25 min treadmill going up to 3.2 mph and it showed that I only went .1 mile yet my treadmill registered 1.6 km.  I did approach fitbit but their answer was not right.  I am 71 only 5'1 with a short stride.  Think I will register my treadmill activity manually.

[Heybales]

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@beth2c wrote:

I am having the same issue.  I did a 25 min treadmill going up to 3.2 mph and it showed that I only went .1 mile yet my treadmill registered 1.6 km.  I did approach fitbit but their answer was not right.  I am 71 only 5'1 with a short stride.  Think I will register my treadmill activity manually.

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This may be a result too of it not seeing the impacts of steps good enough.

Which means the distance may be off, which means calorie burn will be off.

Suggest doing an initial workout at about 1.8 mph for 1/2 mile only. Start and stop the Fitbit workout manually for that.

Now you'll have a known distance (if treadmill is accurate), known steps, and can workout your stride length for the pace about in the middle of your daily paces from grocery store shuffle up to exercise pace.

The Fitbit calculations adjust each step distance based on expected impact and seen impact by accelerometer.

[beth2c]

Hi, thanks for the info. I registered my treadmill manually this morning
and ironically fitbit picked it up as 'walking' and gave me a more
reasonable amount of steps which is more acceptable. At 71 it can
sometimes be difficult to maintain 10K daily and after just recovering from
major surgery I found it disheartening to see my restarting workouts on the
treadmill being recognized so poorly with fitbit.
Cheers,
*Beth *