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MyFitnessPal Community

Fitbit

hypodonthaveme

I have a Fitbit Inspire HR. What is the percentage one should subtract from the calorie burn the Fitbit says you burned for a more accurate number?
Say Fitbit says cardio burned 260 calories for the 30 minute workout, should I subtract 10,20,30% or that number for a more accurate burn?
Not sure how all this works. Last time I needed to lose weight I didn’t have a Fitbit. And didn’t have my fitness pal until 1/2 way through my journey. Due to things I had no control over in the past couple years I’m needed to lose again.

I know these are tools and won’t do the work. But I’m hoping it will help me as I start fresh.

I know it’s calories in calories out. I also know that everything has a curve to accuracy.

Just curious is the charger 3 better than the inspire?

Thank you in advance for the help.

Replies

hipari

There's no one-size-fits-all answer. For me personally, the Fitbit burn number is pretty accurate, but I know many say it isn't accurate for them. The only way to really know is to eat according to that number for an extended period of time (several weeks), log food precisely for that time period, and then do the math to see how accurate it was.

Simple example: if your Fitbit says you burn 2075 calories every single day and you have a goal of losing 1lb per week, you need a 500 calorie deficit. You would then eat 1575 calories per day (or 500 calories less than the daily burn) every day for a few weeks, and see how your weight changes. Then, adjust accordingly.

260 calories for a 30-minute workout sounds plausible if it was a rigorous workout or you are heavy.

nanastaci2020

Do you have Fitbit linked to MFP? If so, Fitbit sends MFP data on your all day calorie burn. Not just your 'exercise' burn. Here is a summary:

MFP estimates what you should burn in a day based on your stats (height, age, weight, gender) and your stated activity level. It figures out your BMR and how much additional energy you use for normal daily activity. Lets say this # is 2400 calories per day. (Just because the math is easy.) That means MFP predicts you'll use 100 cals per hour. *You're expected to log exercise.

When you use Fitbit, it also calculates your all day burn using your stats and by monitoring your movement.

If you link MFP and Fitbit, then Fitbit sends data to MFP for how many cals you've burned so far. MFP compares that to its own prediction and the result is an adjustment.

Example, assuming your BMR is 1800 per day (75 per hour) you wake up at 6am and sync. Fitbit says your total burned so far is 455 because you're really not done anything yet. MFP thinks you would have burned 600 so you're behind. You'll see 0 or -145 depending on your settings.

But then your day unfolds. You do normal daily activity stuff AND run for an hour. At 6pm you sync, and Fitbit says your total burn so far is 2000. MFP @ 6pm would have expected it to be 1800 so you see +200 adjustment.

Each time you Sync, Fitbit sends data and MFP compares and adjusts.

SO whether or not you trust that adjustment? Only time will tell. I find my Fitbit to be accurate (maybe even a tiny bit low) in calculating my calorie burn. Based on weight loss/logging results over the years. Others find theirs to be high.

hypodonthaveme

Well isn’t that something. That is pretty neat. Thank you. I will have the hubby help me link it tonight when he gets home. 😁

nanastaci2020

One thing I like about the Fitbit app:

It does not assume you will burn calories, like MFP does, other than BMR. Instead it awards them as you earn them. I do not log food in Fitbit but I do have my weight loss goal set there. So the 'food calories' value that the Fitbit app says I can will increase as I move during the day. I use this to judge how much more I need to do.

Example: my current total daily burn is around 1650-1700 with 5000+ steps. Some of those are 'normal activity' and some are intentional cardio walking. My food intake goal is 1400 (for a 250 deficit based on 1650). I try to get a walk in early morning. Right now, Fitbit says I have a total of 1258 calories to consume for the day. Which means if I did nothing more today I would burn a total of about 1508. Not enough, so I will move more. Granted it is only 9:35am so I'll move more no matter what. But my mental note of when I can be 'done' for the day: I want to see the Fitbit calories in available # to be 1400++.

hypodonthaveme

Thank you. This is all informative and I truly appreciate it.

nanastaci2020

The data, and how Fitbit & MFP work together confuses a lot of people. Feel free to ask if you come across any questions. I've used Fitbit for 6 1/2 years and found it a great tool to measure my movement. And at many times, identify my lack of movement as being a habit I needed to change lol.

General recommendations:
*Log food in MFP
*No need to 'log' step based activity as the Fitbit will track it
*If you have non-step based activity like swimming, biking: log in Fitbit so its included in the calorie data that Fitbit sends over to MFP. Though some types of Fitbit devices can track these thru an exercise function.

hypodonthaveme

Thank you and I sure will ask as the questions pop up. 😁

Jacq_qui

Sorry to hijack your thread but I'm really struggling to understand whether my fitbit is accurate! Mine is also linked to MFP. At the end of every day I have a tonne of extra calories to eat and not only am I anxious about eating them, I'm anxious about not eating them too as I want to gain some muscle this year.

For example today: My goal is 1460. I've eaten: 1711 calories, which I'm happy with, it's seems sensible. But Fitbit has said that I've burnt 1302 calories, giving me a net of 409 calories. I'm seriously wondering how I'm supposed to find another 1000 calories? I've been pretty active today: HIIT with some weights on the bodyweight moves, I scooted with my daughter with her on on my scooter (she's 22kg! and has a special stand so she can ride with me) and I've done a 6km walk. But 1000 extra calories is crazy. Usually I have 500-600 left at the end of the day. I just find it hard to believe I eat plenty but still have to find something else that's healthy and calorie dense. I'm not far from my target so I know getting it wrong is easy. And I know some people don't eat exercise calories back, and others don't trust their fitbit calcs. It all feels like guesswork!

janejellyroll

jacqQ2017 wrote: »

Sorry to hijack your thread but I'm really struggling to understand whether my fitbit is accurate! Mine is also linked to MFP. At the end of every day I have a tonne of extra calories to eat and not only am I anxious about eating them, I'm anxious about not eating them too as I want to gain some muscle this year.

For example today: My goal is 1460. I've eaten: 1711 calories, which I'm happy with, it's seems sensible. But Fitbit has said that I've burnt 1302 calories, giving me a net of 409 calories. I'm seriously wondering how I'm supposed to find another 1000 calories? I've been pretty active today: HIIT with some weights on the bodyweight moves, I scooted with my daughter with her on on my scooter (she's 22kg! and has a special stand so she can ride with me) and I've done a 6km walk. But 1000 extra calories is crazy. Usually I have 500-600 left at the end of the day. I just find it hard to believe I eat plenty but still have to find something else that's healthy and calorie dense. I'm not far from my target so I know getting it wrong is easy. And I know some people don't eat exercise calories back, and others don't trust their fitbit calcs. It all feels like guesswork!

Is the 1,302 your total burn for the DAY? If so, it's already included in the amount that MFP has given you.

Jacq_qui

my burn for the day is 2,969 according to my fitbit watch.
The 1,302 is the number that fitbit has sent to MFP.

My homescreen says I've netted 409 cals.

janejellyroll

jacqQ2017 wrote: »

my burn for the day is 2,969 according to my fitbit watch.
The 1,302 is the number that fitbit has sent to MFP.

That's a pretty big adjustment! Some people start with eating back a set portion of the calories (like 50 to 75%), give it a few weeks, and then adjust based on real life results. I began by eating back 100% of my adjustments and after a month I found I was losing as expected so I kept eating them.

Jacq_qui

It's a massive number. I find it hard to believe. It's a lot of calories to consume if fitbit is wrong. It's a lot to be under if it's not! I don't think I could find another 1000 calories if I tried. Two shredded wheat and some milk might have to do.....

nanastaci2020

What are your stats?

hypodonthaveme

No worries about high jacking a thread glad you asked.

PAV8888

Connect Trendweight.com with Fitbit.com
Log daily weight in Fitbit; it will auto-transfer the info to trendweight (and MFP)
Make sure sync between MFP and Fitbit is working.
Fill spreadsheet I will link to.
Adjust as needed.

Yes its a lot of work to do all this on a daily basis; and yes, shortcuts to the same results exist by using bulk information from 4-6 weeks worth of solid logging.

To make Fitbit as accurate as possible make sure your personal info (height, weight, age, etc) is accurate. Time zones match between mfp and fitbit? If numbers seem too far out of whack validate stride length.

Please realize that inaccurate food and drink logging in MFP will contribute to the apparent accuracy of Fitbit.

Short term your weight will change for too many reasons to list. Long term your weight trend will change based on caloric balance absent a medical issue.

non-steady state high heart rate activity (such as circuit training) will contribute to inaccuracy. You're doing some of this.

What is your "scooter action" detecting as in Fitbit? I would look at my fitbit and see whether it was detected as running, or biking, and assigned an incorrect number of calories.

Here are the approximate MET values for scooter activity:
TBD 4.0 Self-propelled scooter, 80 meters/minute5
TBD 4.3 Self-propelled scooter, 110 meters/minute5
TBD 5.0 Self-propelled scooter, 140 meters/minute5

Kijima, A., Arimoto, M., & Muramatsu, S. (2007). Metabolic Equivalents during Scooter Exercise. Journal of physiological anthropology, 26(4), 495-499.

Compare:
17190 3.5 17190 3.3 17190 3.5 walking, 2.8 to 3.2 mph, level, moderate pace, firm surface
17200 4.0 17200 3.8 17200 4.3 walking, 3.5 mph, level, brisk, firm surface, walking for exercise
17220 4.0 17220 5.0 17220 5.0 walking, 4.0 mph, level, firm surface, very brisk pace

If the number of calories is wrong but the activities are "usual", no worries: consistent errors can be worked around over time.

Here is a link to the spreadsheet I used to use to calculate my "fitbit error". Shout out to JL who contributed the example numbers! Please COPY and save the sheet to your own google drive before trying to make changes.

https://docs.google.com/spreadsheets/d/1VDmqNpLPu7sbQSochUJNXdp2F7AN15AGgkvS3zLw1GU/edit?usp=sharing

Jacq_qui

nanamerriman2020 wrote: »

What are your stats?

67.8kg, 170cm

Jacq_qui

PAV8888 wrote: »

Connect Trendweight.com with Fitbit.com
Log daily weight in Fitbit; it will auto-transfer the info to trendweight (and MFP)
Make sure sync between MFP and Fitbit is working.
Fill spreadsheet I will link to.
Adjust as needed.

Yes its a lot of work to do all this on a daily basis; and yes, shortcuts to the same results exist by using bulk information from 4-6 weeks worth of solid logging.

To make Fitbit as accurate as possible make sure your personal info (height, weight, age, etc) is accurate. Time zones match between mfp and fitbit? If numbers seem too far out of whack validate stride length.

Please realize that inaccurate food and drink logging in MFP will contribute to the apparent accuracy of Fitbit.

Short term your weight will change for too many reasons to list. Long term your weight trend will change based on caloric balance absent a medical issue.

non-steady state high heart rate activity (such as circuit training) will contribute to inaccuracy. You're doing some of this.

What is your "scooter action" detecting as in Fitbit? I would look at my fitbit and see whether it was detected as running, or biking, and assigned an incorrect number of calories.

Here are the approximate MET values for scooter activity:
TBD 4.0 Self-propelled scooter, 80 meters/minute5
TBD 4.3 Self-propelled scooter, 110 meters/minute5
TBD 5.0 Self-propelled scooter, 140 meters/minute5

Kijima, A., Arimoto, M., & Muramatsu, S. (2007). Metabolic Equivalents during Scooter Exercise. Journal of physiological anthropology, 26(4), 495-499.

Compare:
17190 3.5 17190 3.3 17190 3.5 walking, 2.8 to 3.2 mph, level, moderate pace, firm surface
17200 4.0 17200 3.8 17200 4.3 walking, 3.5 mph, level, brisk, firm surface, walking for exercise
17220 4.0 17220 5.0 17220 5.0 walking, 4.0 mph, level, firm surface, very brisk pace

If the number of calories is wrong but the activities are "usual", no worries: consistent errors can be worked around over time.

Here is a link to the spreadsheet I used to use to calculate my "fitbit error". Shout out to JL who contributed the example numbers! Please COPY and save the sheet to your own google drive before trying to make changes.

https://docs.google.com/spreadsheets/d/1VDmqNpLPu7sbQSochUJNXdp2F7AN15AGgkvS3zLw1GU/edit?usp=sharing

Thank you for this. I did wonder if the HIIT might be an issue. If it's 40s on/20 off then it might be assuming I'm still working whilst my hr is recovering.

I didn't bother logging the scooting in fitbit - it picks up the steps, it doesn't usually auto-detect anything - I guess because my arms are fairly stable and it probably just reads the steps (even if it's just on one side). Scooting isn't a daily activity though, and I've always got a high adjustment number. Because fitbit calcs my all-day burn regardless of whether I press the button, I don't record every work out I do. (Is this wrong!?) (Eg I use my hip/booty band several times a week but I don't record it for the ten minutes I use it, or I play football in the garden with the kids, it'll auto-detect that as walking so I tend to ignore it.)

Will copy the sheet over and see what I can find out. Thank you.

nanastaci2020

jacqQ2017 wrote: »

nanamerriman2020 wrote: »

What are your stats?

67.8kg, 170cm

Editing as my #s were off.

BMR is about 1400 approximately, or burning 1700-1800 with normal daily activity before exercise. So 2900+ burned in a day: super active or has an error.

Make sure Fitbit has your stats correct?

PAV8888

jacqQ2017 wrote: »

I didn't bother logging the scooting in fitbit - it picks up the steps, it doesn't usually auto-detect anything - I guess because my arms are fairly stable and it probably just reads the steps (even if it's just on one side). Scooting isn't a daily activity though

That's fine then. It is not an impediment in getting useful information, especially when it is not a daily activity.

jacqQ2017 wrote: »

and I've always got a high adjustment number

This could be because of HR detection... what is your Fitbit resting HR? Or it could just be that you actually DO do a lot!

jacqQ2017 wrote: »

Because fitbit calcs my all-day burn regardless of whether I press the button, I don't record every work out I do. (Is this wrong!?)

Absolutely not. In fact, I can't remember the last time I recorded a workout manually. If anything I go in and delete the occasional mis-detected cycling or running workout, only leaving the steps that were added to contribute to calories (as opposed to taking the HR info and activity multiplier into account as an formally recorded exercise tends to do).

Re; the sheet. You can glean the same information by using cumulative stats instead of logging every single day. You would need to go through MFP to record calories in, through Fitbit to get calories out. And, may I suggest, trendweight to look at your weight trend.... you should be comparing 4-6 week time periods that include a complete hormonal cycle in order to account for water weight variations because of such.

Jacq_qui

nanamerriman2020 wrote: »

Make sure Fitbit has your stats correct?

Thanks I just checked the height, weight, age and gender are correct. Is there anything else it takes into consideration?

Yesterday's were really high, today's burn at 9pm is 2385cals, 8.7km/12,609 steps, 116 active minutes. I have no idea whether this is particularly active, but for me it's a more normal day than yesterday. I'm going to study now so won't move an awful lot more - except maybe a few press ups when I move away from my desk!

Jacq_qui

PAV8888 wrote: »

jacqQ2017 wrote: »

and I've always got a high adjustment number

This could be because of HR detection... what is your Fitbit resting HR? Or it could just be that you actually DO do a lot!

Resting hr between 58-63bpm, depending on how tired I am (I study in the evenings, run around after kids in teh day). Today it's 62bpm.

PAV8888 wrote: »

Absolutely not. In fact, I can't remember the last time I recorded a workout manually. If anything I go in and delete the occasional mis-detected cycling or running workout, only leaving the steps that were added to contribute to calories (as opposed to taking the HR info and activity multiplier into account as an formally recorded exercise tends to do).

Good to know.

PAV8888 wrote: »

Re; the sheet. You can glean the same information by using cumulative stats instead of logging every single day. You would need to go through MFP to record calories in, through Fitbit to get calories out. And, may I suggest, trendweight to look at your weight trend.... you should be comparing 4-6 week time periods that include a complete hormonal cycle in order to account for water weight variations because of such.

The sheet looks good. I've registered with trendweight and hopefully can get some good data over the next few weeks. I don't like the guessing element in all of this; I like to make decisions based on good data

PAV8888

12,609 steps is into MFPs very active zone (absent you using a Fitbit).

If your Cals to midnight on Fitbit are well above what MFP's very active calories would have been, then it would be an indication of concern about the accuracy.

5000-- you're into lightly active
8000 -- just about the limit of lightly active
12000 -- just about the limit of active
16000 -- just about the limit of very active

Your food logging accuracy, water retention, propensity to track with the mean all play as big or bigger of a role into how "apparently" accurate your fitbit is.

Are you using a weight trend app for your weight and comparing similar points of your monthly cycle and taking into account at least 4-6 weeks at a time?

Jacq_qui

Up until today I was not using a weight trend app, only looking at graphs provided by my wifi scales (not withings, not fitbit but shows data over long time periods)

My MFP activity level is set to sedentary because yesterday I racked up 16k steps, today it's 12k, and the weekend tends to be less (maybe 8k) because I end up working all day when I have my husband to look after the kids. I figured it would be better to have bigger adjustments in the week than suddenly trying to eat less at the weekends. Most days I've eaten under. Today I have 734 cals left to 'net 1440, but if this were accurate I'd be losing a significant amount of weight each week, and I'm not, so something is up somewhere.

If your Cals to midnight on Fitbit are well above what MFP's very active calories would have been, then it would be an indication of concern about the accuracy.

How can I see what MFP's very active calorie estimate is?

PAV8888

Trial and error by changing settings but it doesn't matter.

Sounds like your estimates are out of whack with weight trend results more so than as to their absolute value.

Which is ok because you can adjust based on results as long as your logging in/out is consistent. You only need consistency, not accuracy to achieve results (of course absolute accuracy also means absolute consistency, but it is not necessary)