Incorporate Body Fat % into BMR/RMR calculations!

[Knowledge]

Right now I believe Fitbit uses your height, age, and weight to calculate your BMR (Basal Metabolic Rate) which is the calories you burn if you did absolutely nothing all day just by living and breathing and then adds calories burned due to steps/activity/heart rate to that.

Problem is calculating BMR with just height/weight/age BMR is a very poor way of calculating it. Of course for people who don't have body fat measurements, it's easy. But many of us including myself either manually enter in our calculated Body Fat, or they use the Fitbit Aria Scale which automatically calculates body fat and syncs to the dashboard.

I would like to see Body Fat implemented in the calorie burn estimations because I really feel this will help accurately measure my calorie burn (if for example I weight 250 lbs and have 15% body fat I will be burning way more calories per day by just living than someone weighing 250 lbs and having 30% body fat).

This can be simply done using a commonly used BMR equation that incorporates body fat. Obviously if someone hasn't enetered in their Body Fat measurements than it would default to the age/height/weight but please gives those of us with more detailed body info more accurate calorie burn!

Moderator edit: Added labels.

[laurieb90]

I've been thinking this would be a great idea! I think I have quite a high body fat % for my weight (no muscle haha) so I think my fitbit is probably overestimating the calories I'm burning.

Also, I have been considering buying a fitbit aria and I think this would make me much more likely to do so!

[SunsetRunner]

Didn't know body fat affects calories burned, awesome idea!

[techjunkie860]

I would like them to add measurements (Biceps, legs, chest, back, neck, etc.) too. I currently use jefit to track my measurements. I would prefer to have everything in one place.

[dweebgal1]

Please do incorporate this lovely fitbit, when you're someone on the rather chunky side with a higher bf% , it would be lovely to see a more accurate reading for calories burned

[Lars-Christian]

Would love to see this.

If you know your bodyfat percentage, basal metabolic rate and max bpm (heart rate) it would be great to add this to the calculations. Will certainly make for a more correct measurement.

I don't have the Aria, but given this product, it BF% should have a place in the Fitbit profile.

LC

[DerrickS]

 @Knowledge This is a really well thought out idea. One thing that is important to note is that if you have a heart rate tracker, HR is also factored into your BMR. 

I really like this idea and I'll be sure to relay it to the rest of the team. Thanks for posting on the Feature Request Board!

[JohnFM]

I agree with this and it represents the biggest flaw with the fitbit system.

In addition, since there is not a very good consensus on RMR for obese people we should be allowed to enter a percentage value for fat.

One theory is that calculating RMR for fat should be based on 25% of the fat mass such that a person weighing 300 lbs with 200lb of lean mass should have BMR's based on 225 lbs (200 + 25% of 100). This is the calc that I am using but I cannot enter the daily caloric requirement that I am targeting nor can I adjust the BMR equation!!! I essentially have to ignore the 4100 calorie a day requirement, and yes, that is WITH a 1000 calorie deficit!!!

If I manually enter a daily calorie target, half of the fitbit functionality goes away. This is annoying!

[stemloop]

THIS IS BADLY NEEDED.  Right now I assume Fitbit uses your age, heart rate data, and BMI, and then will calculate a different estimate for calories burned based on your gender, which is to say a proxy for body fat%- as women will carry more fat/less muscle on average for a given BMI (heigh/weight metric) than men, due to the effect of testosterone on body composition and muscle mass.  However, this is a very broad brush to take, as body fat% (and thus calorie burn rate) can still vary quite a bit within a given age+gender+BMI and merely using age+gender+BMI as a proxy for BF%/caloric needs DOES NOT satisfactorily account for this variability.  This results in Fitbit calorie burn estimates really only working for the median or average female/male user.  Right now Fitbit is squandering the data advantage offered by a HR monitor that measures activity levels.

Edit: Also, BF% based on electrical conductivity/resistance measurements such as those provided by scales like the Aria are typically quite inaccurate, although they may be precise in their inaccuracy.  Using the Aria does not address this issue and users should be able to input their own BF% data to arrive at a more accurate metabolic rate estimate.

[Tooraj]

You might also want to see and vote for this feature request:

https://community.fitbit.com/t5/Feature-Requests/Customizable-BMR-or-resting-calorie-burn/idc-p/9537...

[LizFitbit]

Hi everyone, thanks for sharing this suggestion. In terms of an update, there aren't currently any plans to release this feature. Thanks for taking the time to share your feedback with us and we will let you know if anything changes.

[Shagraey]

I would love to see this option implemented in the near future for best accuracy. 

[LizFitbit]

Hi @Knowledge and thanks for sharing this suggestion, which has received votes from other community members. I’m happy to let you know that this suggestion has been picked up internally at Fitbit and is being considered by our team. This suggestion will either remain ‘Under Consideration’ until released, or else move to ‘Not Currently Planned’ if it’s not viable right now. Further updates will be posted here.

Please remember that if a suggestion is chosen for development, it can take some time before updates are available or a release is finalized, so thanks in advance for your patience :). To learn more about how Fitbit decides which suggestions get developed, visit our FAQs. Fans can continue to vote for this feature suggestion while it is under consideration.

[livhs]

I also think this needs to be added as a feature, it would be really great!

[bfmumme]

There are several of us who are outside the norm in fitness, and the Charge 3 should work for us as well.  There should be a way for us to input our medically tested BMR or RMR, or enter actual body-fat % so the watch will accurately report our calories burned during the day.

There must be a patch, fix, trick, that users can input so that the data is correct.

I am a 50 year old male, with 6% body-fat, and my watch is grossly (and I mean grossly) wrong with my BMR, and calories burned during exercise.

There must be a way to correct this, and if not, this watch is not for the serious athlete.

So what's out there as a fix for this problem?

[YojanaFitbit]

Hi @bfmumme, thanks for explaining why you would like to have this option on the Fitbit app. I've moved it into a similar suggestion which has been updated as "Under Consideration". You can learn more about here. You might be interested in voting for this other suggestion: Allow users to enter a customized BMR or RMR. Keep adding your suggestions!

[bfmumme]

This is an excellant recommendation, and actually surprising that Fitbit does nto already do this.  Most who own a Fitbit device, are obviously very interested in their fitness, and thus, are more prone to have either lower than normal body fat, or at least the testing done so that they know exactly their current body fat %, with a goal in mind to reduce.  Most that are paying attention to their fitness, recognise that weight is not a good metric of health; rather, body composition (lean mass, bone density, and body fat %) is far more descriptive of someone's health.

As a Fitbit user, I expect more from Fitbit, and do anticipate that the "health conscientious" developers at Fitbit will correct this.

[arcanaeum]

+1.

I find it extraordinary that this wasn't part of the original design of the app/Fitbit products. The fact that this has taken almost 5 years to even be considered is absolutely astounding. This is such a fundamental requirement for any serious fitness use - without it you're looking at a poor estimate at best. 

It seems as though Fitbit is not intended for serious fitness use. Perhaps I should look elsewhere?

[MrCrg]

Can't a body fat percentage calculator be included when inputting manual weight? It's a hassle having to leave the app, go online, use a calculator, then return to input data that the app could reasonably have provided. We don't all own Arias! Manual input should remain an option though.

[YojanaFitbit]

Hi @MrCrg, thanks for explaining why you would like to have the option to include a body fat percentage calculator when you log weight. I've moved it into a similar suggestion which has been updated as "Under Consideration". You can learn more about it here. I hope to see you around.

[HSS79]

Please add body fat % beside the weight. Currently it only displays the weight example "115kg". User have to click on that to see more information on the next screen which loads really slow.

Make it such that we can see the weight and body fat % example, 115kg/80%.

[YojanaFitbit]

Hi @HSS79, thanks for explaining why you would like to have the option to see body fat percentage. I've moved it into a similar suggestion which has been updated as "Under Consideration". I hope to see you around.

[Dr.Kate]

I'm glad this is still "under consideration" but since it's been a year without any additional comments, I'm adding my strong support for the ability to use body fat percentage in Fitbit's calculation of BMR. Please!! (Other readers: Please keep voting for the original post!)

I've been trying to figure out how Fitbit is underestimating my daily calories burned, when most articles I find are about how this and similar devices tend to overestimate active calorie burn. I came to the conclusion that it must be underestimating my BMR. 

It seems clear from other community posts and looking at online calculators that the Fitbit software uses the Mifflin-St.Jeor formula to estimate BMR from gender, age, height, and weight. Using that formula, my estimated BMR is ~1150 kcal, which matches the 12 kcal/15 minutes basal expenditure that Fitbit shows for me during sleep. 

I've never had a "real" body fat measurement, but using the Navy and Covert-Bailey tape measure methods my estimate is 20-25%, which is pretty average for a fit woman. Using the Katch-McArdle BMR formula which incorporates body fat percentage, my estimated BMR is 1250-1300 kcal. Playing around with different body fat values in the formula, it seems the Mifflin-St. Jeor estimate for women assumes body fat of ~33%!! 

So, OK... I'm now no longer surprised that I lost weight WAY faster than expected with a theoretical 250 kcal/day deficit when I originally started, because in reality it was a 350-400 kcal deficit. And it matches the fact that I now have to eat 100 kcal/day OVER what Fitbit estimates, just to maintain weight. But that's super annoying, because as I continue to build muscle I'm going to have to track body fat and Katch-McArdle BMR in a separate spreadsheet in order to figure out how much to mentally increase Fitbit's estimated maintenance amount. 

Here's the thing that really gets me, though... When originally setting up my Fitbit profile, it asked my gender, age, height, weight... AND BODY FAT PERCENTAGE. I hadn't done the measurements at that time, so I accepted the default value for women that it offered me... which was 21%! Why in the world would it offer a default value that does not match the assumed value in the formula it uses?? This is bonkers. And, every time I log a weight, I have the option to input body fat %, and obviously if I had something like an Aria scale it would import that value automatically each time I measured it. But... Fitbit doesn't do anything with that value except make a graph? 

This is an easy fix. Just math. I have minimal coding experience and I imagine I could figure out where in the software to add an if/then statement to look for an entered body fat value and select the formula used to estimate BMR. Not trying to be overly snarky here, just... this would not be very taxing to your software developers at all, and would vastly improve the utility of your devices to the two populations you target the most - fitness enthusiasts with lower than average body fat percentage, and those of currently higher than average body fat percentage who want to get fitter. 

[bfmumme]

100% Agreed! Accurate calorie burn must incorporate your lean mass.
I am a male, 52, 187 lbs and my body fat is 10%. My fitbit is easily 20%
off with respect to my daily caloric burn.