Inaccurate calorie count for walking

[Lena_Amsterdam]

Hi! Does anyone know if Fitbit has any plans to fix the wildly inaccurate calorie counts for walking? 

I have no problem with running, which is pretty spot-on. Same for cycling. But walking is overestimated by a factor of 3. I have seen quite a number of people complaining about it in different posts for the last year or two, but I cannot seem to find any relevant response from Fitbit as to whether this will be fixed sometime soon. 

Thank you!

[Mukluk4]

Which tracker do you use?  Have yo verified that your stride length is correct?

[USAF-Larry]

@Lena_Amsterdam, could you provide some examples of why you believe it is overestimating calories by 3X for walking over running or cycling.  I don't recall seeing "quite a number" of complaints about this over the last year, can you provide links to some of those posts?

[Lena_Amsterdam]

Hi! Thanks for the replies

I'm using Alta. Stride length should not have much of an impact on calories burned. Of course that depends on how the algorithms work, but at most I'd expect a small variation, not such a big difference.

As an example, I went for a slow 20 min walk this morning, about a mile in length, and Fitbit tells me I burned 181 calories. Excluding BMR, it should be around 55-60. Including BMR, let's say max 90. 

If you check the Fitbit community forum for innacurate calories for walking, you'll find several discussions with a number of people saying the same thing. I would have thought this was a known issue and is being corrected. 

By comparison, same exercise in MyFitnessPal is less than 90kcal.

[Mukluk4]

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@Lena_Amsterdam wrote:

Hi! Thanks for the replies

I'm using Alta. Stride length should not have much of an impact on calories burned. Of course that depends on how the algorithms work, but at most I'd expect a small variation, not such a big difference.

By comparison, same exercise in MyFitnessPal is less than 90kcal.

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Depending how far your stride length is off, it can be a huge difference.  You can test it by going for the same distance with various stride lengths.  I would start by calibrating that first and once that's complete then compare.  If it's still an issue, contact support or post in your tracker specific board.

[Lena_Amsterdam]

Thank you, but my stride length is relatively correct (20 min, 1 mile, is pretty accurate given I was walking slowly, maybe 3mph).

The issue is also not tracker related - I believe it's the algorithm that supports the calorie calculation. 

Thanks anyway

[baitedbadger]

I posted the other day at my surprise that running 5k burns less calories than walking 5k ... So the hare burns less calories than the tortoise in a race ... 

But if I walk 5km in an hour, I burn about 5x70cals plus my BMR, in my case that is about 420 Cal's. which seems right to me, I link GPS so know distance is accurate.

Does the calories burned include BMR for the duration of the walk?

[Mukluk4]

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@Lena_Amsterdam wrote:

Thank you, but my stride length is relatively correct (20 min, 1 mile, is pretty accurate given I was walking slowly, maybe 3mph).

The issue is also not tracker related - I believe it's the algorithm that supports the calorie calculation. 

Thanks anyway

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Stride is steps per mile, not time per mile

[Mukluk4]

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@baitedbadger wrote:

Does the calories burned include BMR for the duration of the walk?

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Yes

[Lena_Amsterdam]

And if my stride length was incorrect, would 20 min walk at approximately 3 mph result in 1 mile in distance? 

[Mukluk4]

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@Lena_Amsterdam wrote:

And if my stride length was incorrect, would 20 min walk at approximately 3 mph result in 1 mile in distance? 

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The two are completely unrelated.  

MPH is Distance/Time .  It doesn't matter if you take 30, 12, 200, 20000 steps to get to 1 mile in 20 minutes.

Stride is Steps/Distance.  It doesn't matter how fast you walk, but how many steps to get to that distance.

[Lena_Amsterdam]

Perhaps if I rephrase:

I walked 20 min at approximately 3mph. I know this independently of Fitbit as I can approximate my speed well and I have a watch (plus Fitbit also tracks time. Accurately). So that is 1 mile walked.

Fitbit tells me I walked 1 mile. It calculates distance on stride length times number of steps. Number of steps is reasonably accurate.

Both assessments agree that I walked 1 mile. There is no potential for stride length to be significantly incorrect in that equation 🙂

[Lena_Amsterdam]

Ha! Yeah, under normal circumstances, you definitely burn more calories running 5k than walking it 😄 There are some really cool studies done where this is not the case (such as efficiency/effort-related gains- if you try to walk at 5+mph the effort and calorie expenditure is actually higher than running at the same speed due to the mechanics of both activities, but I'm digressing).

it has been disproven over and over again that walking and running burn the same amount of calories per mile. But I don't think anyone would agree that running burns less than walking over the same distance 🙂 

[baitedbadger]

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@Mukluk4 wrote:

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@baitedbadger wrote:

Does the calories burned include BMR for the duration of the walk?

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Yes

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in that case, my charge2 is reasonably consistant with what I'd expect. 112 cal per mile + BMR which is consistant with google results 🙂

[GershonSurge]

@Mukluk4, @Lena_Amsterdam,

The Alta doesn't have GPS, so if it shows Lena walks about a 20 minute mile, it's probably close enough.

The most efficient speed for most people to walk is 3.5 mph. Wish I had the link handy. Anyway, the point is if a person walks slower, they burn more calories per mile just like the person who walks faster.

180 calories per mile is not out of the ballpark depending on weight and fitness level. 
Many of the charts don't include BMR calories. The Fitbit does.

[Lena_Amsterdam]

@GershonSurge You're right, 180 kcal is probably about right if a person weighs 300 lb. But a person of average weight burns less than half that (very much including BMR) for a 20 min walk. 

Given that I'm not 300 lb, it's counting the calories wrong for my situation 😞

Never mind, I guess there isn't an answer to my question 🙂 

[GershonSurge]

@Lena_Amsterdam,

I used to track calories/mile vs steps/min. I was 6'0 and 175 pounds then.

[Dominique]

FWIW, I currently wear three Fitbits: Surge, Charge 2 and Alta HR. This morning, I did a 5.5 km walk in 54 minutes one way, and (slightly later on) 5.5 km in 53 minutes on the way back (average speed: 6.1 km = 3.8 mph). I recorded both with my Surge. These same walks were autodetected by my Charge 2 and Alta HR.

Here were the calories for each tracker:

Surge: 486 + 446 (avg: 466)

Charge 2: 443 + 415 (avg: 429)

Alta HR: 482 + 479 (avg: 480)

According to the Compendium of Physical activities, "walking at 4.0 mph on level, firm surface" is 5.0 METS. I actually walked on uneven, non-flat terrain, which was probably more demanding. My calculated BMR is 1438, so in 55 minutes I would expend 5.0 x 55 x 1438 / 1440 = 275 calories. Based on that, all three Fitbits would overestimate calories burned, but not by a factor of 3.

[Lena_Amsterdam]

@Dominique Thanks for the reply 🙂 

i personally dont don't agree with BMR kcal being part of exercise calories because I think exercise calories should track what activity I add to my day by choosing to exercise- and I didn't know if they were or were not included on Fitbit - so from that perspective you are indeed correct, it's not by a factor of 3, if taking BMR into account.

i have to be honest, I don't know how mets work and I cannot follow your math 🙂 but I would expect around 250 kcal incl BMR for a workout such as you described (of course this depends heavily on weight and a few other things I won't go into so as not to over complicate the issue) - which is pretty close to your estimation. Still pretty far from what Fitbits recorded.

it's fascinating to see the variation between the trackers, thank you for sharing that! 🙂 

[Lena_Amsterdam]

@GershonSurge Hey! Again, thanks for the reply. I don't mean to start an argument and you're welcome not to believe me, but there is not a snowflake's chance in hell you're burning anywhere near the vicinity of 180 kcal walking one mile at the weight you stated. Don't take my word for it, I'm just some random on the internet :), but by all means do look it up. There is plenty of research and evidence available to support what I'm saying 🙂