Calories burned not as accuate as Strava

[SunsetRunner]

I commuted to work today by bike which is all downhill and used Strava to track it. Strava said I burned 34 Calories, but when it synced to Fitbit my activity log showed 82 calories (which would make sense if I was on a flat surface traveling at the average speed I was). I'm thinking that Strava is probably more accurate because it can take into account the elevation gain and weight of the bike into the calorie count. Is there any way to override Fitbit's calorie counter and use Strava's? I use a Fitbit One.

[TandemWalker]

Hi @SunsetRunner. The Fitbit reports calories burned from activities as the sum of your BMR plus the incremental burn from exercise. I am not familiar with Strava - but do you know if BMR is included in Strava's numbers? What happens if you log cycling manually, keying in the actual duration of the your bike run and distance? If you all you did is sync'd, Fitbit is reporting calories burned from the 'false' steps' it recorded during your bike run, the result of which (calories wise) is somewhat meaningless. I never wear my One for cycling; and if I had to, I would definitely override whatever it gives me with a manual log. When you log cycling manually, Fitbit will calculate the burn; but if you don't like it, you can delete the entry and key it in again with your own caloric burn. Cheers!

TW

[SunsetRunner]

When I do a manual log set at a different time that I wasn't very active, I get the same (I'm assuming incorrect) caloric burn.

It just sucks that since I have my Strava account linked that I'd have to come back in and manually record my burn from it, might as well not have it sync'd.

[TandemWalker]

That's right @SunsetRunner, you will get the exact same burn when logging a bike run, whether you do so when you were active or inactive. Either way, Fitbit overrides whatever burn your Fitbit One recorded with the burn that it calculates. You can check the caloric burn with other web sites and see which of Fitbit or Strava is more accurate. I know that the calculators at https://www.healthstatus.com/perl/calculator.cgi are pretty accurate.

Another suggestion is to avoid using the timer functionality on your One for your bike ride and add the activity record separately, at which time you can key in the burn from Strava is wnat to. To do so, you tap on the small clock and + sign icon at the top right of the "Log Activities" window.

Have a nice day.

TW

[SunsetRunner]

Yeah, I know that's an option. I didn't use timed activity or anything on my One, just carried it with me because it was my morning commute.

Fitbit auto-sync's with Strava when I log something on Strava, and it gets imported into my activity log (which I like) but Fitbit uses it's own calorie calculation based off of limited data (doesn't take into account elevation gain or bike weight).

Like I said, my commute to work is all downhill, so my burn wouldn't be very high at all, like Strava computed.

[TandemWalker]

I would try using the timer next time to segment out your bike run and see what you get. Did you see this help article http://help.fitbit.com/articles/en_US/Help_article/Can-I-connect-my-Strava-and-Fitbit-accounts/?q=st... ?

TW

[SunsetRunner]

Yeah, I'll give that a try for my ride home tonight. But from the article
you linked:

> Note that after linking your accounts you may see some differences in the
> way data is calculated for your exercises on each site. For more
> information, refer to Strava's Calorie Calculation
> article.

And from Strava's support site:

> Calorie calculations are estimates based on power output and a coefficient
> for human efficiency.
>
Their power calculation is pretty in-depth
https://support.strava.com/hc/en-us/articles/216917107-Power-Calculations
This leads me to trust it more than Fitbit's. So I would really like to use
Strava's calorie estimation automatically, instead of having to manually
put it in, which defeats the purpose of having the apps synced.

[TandemWalker]

Well @SunsetRunner, let's see what you get when you use the timer functionality. As for the weight of the bike being a factor, frankly, I don't think this would matter much since you're going downhill. You get roughly a 50 calories delta here over 18 min. - that's an awful lot. Are you absolutely certain that the burn reported by Strava includes BMR calories and not just the incremental burn from cycling?

TW

[SunsetRunner]

EDIT: Picture links didn't work from e-mail, formating

So I did some math this morning. My BMR is around 2cal/min and my ride today was a total of 7:46 (again downhill)

From the Strava website:

My energy expenditure calculated by Strava is 36kJ (8.5cal)

Now from the Strava app It says I've burned 40cal. 40cal-8.5cal = 31.5cal
round up to a 8min ride * 2cal = 16cal BMR during that time period which is 15.5cal off, there might be some other factors in there I''m not aware of that they are factoring in for the incremental bike ride calorie
expenditure.

I did a timed activity in Fitbit and it imported Strava distance and total time I had the app running (9:14) and it gave me the same calorie information for both

at a BMR of 2cal/min*10min = 20cal BMR for a 10min time period that leaves 42cal on the table. Add this to Strava's calculation of 40cal and voila! *Fitbit is double counting my BMR!*

The weight of the bike is also a factor in this because Strava's power calculation takes into account the mass of the bike and rider for determining the power needed to overcome gravity (in the case of downhill
this would be a negative number) and the power needed for acceleration


Now the calorie burn in Strava seems to only be moving time on bike, so if Fitbit where to take total time of the activity subtract out moving time on bike and add BMR to that time, the calories burned report would be more accurate.


TL;DR
Strava calorie counter is moving time on bike + BMR and Fitbit uses that info and adds BMR of the total time to that, double counting BMR while on the bike.

[TandemWalker]

Hi @SunsetRunner. Thank you for the update. Since I'm not familiar with Strava, I am ill-equipped to comment further. I do know that Fitbit does not double BMR on regular acitivities, both tracked and manual logs. So this anomaly is obviously in the interface with Strava. I think your best bet would be to email Support with a link to this thread and see what they say.

http://help.fitbit.com/?l=en_US&cu=1&fs=ContactUs

Take care.

TW