FitBit Accuracy
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trigden1991
Posts: 4,658 Member
Thought I would post a quick summary of my 6 week "study" to evaluate the accuracy of the TDEE figure given by my FitBit Charge:
Total Fitbit Expenditure: 158484 cals
Total Calories Consumed (MFP): 124539 cals
Calorie Deficit: 33945 cals
Assuming 3500cals = 1lb fat lost and no LBM loss:
Calculated Fat loss: 33945/3500 = 9.7lbs
Actual weight loss: 11.3lbs
In the first week I dropped 4lbs so assuming 1.5-2lbs of water weight as I was fully carbed up with full glycogen stores, the Fitbit is relatively accurate.
Nothing scientific and an N=1 study but I see a lot of queries regarding FitBit TDEE values.
Total Fitbit Expenditure: 158484 cals
Total Calories Consumed (MFP): 124539 cals
Calorie Deficit: 33945 cals
Assuming 3500cals = 1lb fat lost and no LBM loss:
Calculated Fat loss: 33945/3500 = 9.7lbs
Actual weight loss: 11.3lbs
In the first week I dropped 4lbs so assuming 1.5-2lbs of water weight as I was fully carbed up with full glycogen stores, the Fitbit is relatively accurate.
Nothing scientific and an N=1 study but I see a lot of queries regarding FitBit TDEE values.
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Replies
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And?0
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Yes, that seems quite accurate. Do you have any advice for how to set the wretched thing up correctly? I see a lot of people struggling with them giving inaccurate numbers.0
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And?
It is what it is; nothing more, nothing less. Just my ramblings and *kitten* packet maths to support the TDEE figures.CattOfTheGarage wrote: »Yes, that seems quite accurate. Do you have any advice for how to set the wretched thing up correctly? I see a lot of people struggling with them giving inaccurate numbers.
I paired it with MFP which has all my stats in and I haven't had to play with any settings at all.0 -
Interesting.
Do you log any exercise using MFP or the Fitbit dashboard? (strength training, etc.)0 -
I love posts like this. Thanks for sharing. Then again, I'm a data geek.
I did a similar experiment on myself and found my Fitbit to be fairly accurate as well. I use it to gauge my TDEE.3 -
Interesting.
Do you log any exercise using MFP or the Fitbit dashboard? (strength training, etc.)
I do not. However my workouts do tend to rack up a number of "steps" (3-4k normally) which at first was an annoyance but 3-4k steps is approximately 250-300 calories for me which reflects an hour of intense weightlifting.0 -
trigden1991 wrote: »And?
It is what it is; nothing more, nothing less. Just my ramblings and *kitten* packet maths to support the TDEE figures.CattOfTheGarage wrote: »Yes, that seems quite accurate. Do you have any advice for how to set the wretched thing up correctly? I see a lot of people struggling with them giving inaccurate numbers.
I paired it with MFP which has all my stats in and I haven't had to play with any settings at all.
Ok, my comment was before you edited and I was wondering how much you actually lost.0 -
Thanks for sharing. I've just been using my blaze and not logging any activity, just using the numbers provided and it's been working out well for me. Nothing is going to be 100% accurate, but my fitbit is doing what I need it to do and I'm happy with it.3
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trigden1991 wrote: »Interesting.
Do you log any exercise using MFP or the Fitbit dashboard? (strength training, etc.)
I do not. However my workouts do tend to rack up a number of "steps" (3-4k normally) which at first was an annoyance but 3-4k steps is approximately 250-300 calories for me which reflects an hour of intense weightlifting.
How do you get so many steps while lifting?0 -
I get a lot of steps while lifting. I walk around during rests between sets. I don't log lifting, I just let my Fitbit track those steps. It's funny, when I lift, my activity log on my Fitbit dashboard usually shows a "Walk" logged for the time I've been lifting. (I have a Charge2 that has an auto-recognize feature for some exercises.)2
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trigden1991 wrote: »Interesting.
Do you log any exercise using MFP or the Fitbit dashboard? (strength training, etc.)
I do not. However my workouts do tend to rack up a number of "steps" (3-4k normally) which at first was an annoyance but 3-4k steps is approximately 250-300 calories for me which reflects an hour of intense weightlifting.
How do you get so many steps while lifting?
Moving my arms counts as steps I assume.trigden1991 wrote: »And?
It is what it is; nothing more, nothing less. Just my ramblings and *kitten* packet maths to support the TDEE figures.CattOfTheGarage wrote: »Yes, that seems quite accurate. Do you have any advice for how to set the wretched thing up correctly? I see a lot of people struggling with them giving inaccurate numbers.
I paired it with MFP which has all my stats in and I haven't had to play with any settings at all.
Ok, my comment was before you edited and I was wondering how much you actually lost.
Apologies, didn't realise anyone was that quick off the mark!0 -
If you're getting so many extra steps for moving your arms, you might consider switching your settings to having your device on your dominant hand, especially if it's giving you a burn for that movement.
I get some arm movement "steps" but not many, and those usually don't give me many calories.
Then again, since you aren't logging weight lifting and the device is working out for you? Since it ain't broke, don't fix it.
Just wanted to put this out there for lurkers.2 -
GottaBurnEmAll wrote: »If you're getting so many extra steps for moving your arms, you might consider switching your settings to having your device on your dominant hand, especially if it's giving you a burn for that movement.
I get some arm movement "steps" but not many, and those usually don't give me many calories.
Then again, since you aren't logging weight lifting and the device is working out for you? Since it ain't broke, don't fix it.
Just wanted to put this out there for lurkers.
Just want to point out though that the dominant hand thing is a bit of a pain for people like me who use both hands for different things. I end up taking my Fitbit off if I have to grate cheese...2 -
GottaBurnEmAll wrote: »If you're getting so many extra steps for moving your arms, you might consider switching your settings to having your device on your dominant hand, especially if it's giving you a burn for that movement.
I get some arm movement "steps" but not many, and those usually don't give me many calories.
Then again, since you aren't logging weight lifting and the device is working out for you? Since it ain't broke, don't fix it.
Just wanted to put this out there for lurkers.
Good addition for anyone reading!
For me; I rack up extra steps but I don't track workouts on MFP which seem to average out nicely.
Back working calories consumed/lbs lost gives my real average TDEE within 5% of the FitBit readings so I'm happy with how its working.0 -
Since we're doing this, here are my numbers (with a Charge 2):
Total Fitbit Expenditure: 366354 cals
Total Calories Consumed (MFP): 300130 cals
Calorie Deficit: 66224 cals
Assuming 3500cals = 1lb fat lost and no LBM loss:
Calculated Fat loss: 66224/3500 = 18.9 lbs
Actual weight loss: 18.5 lbs
This represents about 4.5 months of data.
I don't log any exercise manually at MFP; I let FitBit handle all of it. I only burn about 2x400=800 calories/week "working out" so most of the burn is NEAT (which, I believe, is what FitBit is best at handling). Even when it misses steps (because, for example, I'm pushing a stroller), it seems to get my calorie burn roughly right - so I suspect it uses a slightly elevated heartrate to tell it I'm doing something equivalent to walking. (I've tested this by test-logging the "walk" for the right distance and duration at the FitBit website. Doing that had minimal impact on my daily calorie burn.)
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