Can I bypass the caloric calculation and set it myself?

[Roseman]

I had a biometric analysis done and therefore know my BMR - and I want to set my caloric requirement daily based upon that, not based on the fitbit calculation of my requirements. Can this be done?

[LZeeW]

If you are asking about changing the number in the Calorie tile on the Dashboard, you can do that by clicking on the gear icon you see at the bottom of the tile when you place your cursor over the tile.  You can set your desired daily goal and save that number.

Is this what you are asking?  If not, please clarify.

I think Fitbit uses the Harris-Benedict equation for calculating BMR.  When I put my numbers in the equation for women, I got exactly the same number Fitbit was giving me. 

How close is your number to Fitbit's derived number?  If it is close, you might not want to do anything -- there are inherent inaccuracies in the technology.  It's just not perfect. 

[Heybales]

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@Roseman wrote:

I had a biometric analysis done and therefore know my BMR - and I want to set my caloric requirement daily based upon that, not based on the fitbit calculation of my requirements. Can this be done?

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Biometric?

No - you know your bodyfat %, and from that a different BMR formula than the one Fitbit uses, which is close to Mifflin.

You have the Katch BMR or Cunningham RMR depending on what they gave you.

But indeed, if there is a big difference, good to go off better estimate, which Katch BMR would be.

You aren't just going to eat that much right?

If you like, there's an easier way. Let Fitbit base it's calories on your better estimate, then just use the given diet plans of 1/2, 1, 1.5, ect loss weekly.

Change your height on Fitbit until the BMR they use for all non-moving time matches your Katch BMR from bodyfat %.

That way it's still estimating moving calories based on weight and pace, and your non-moving time is acutally based on your better estimate.

Here's the backwards formula to figure out your cm to set your height to, convert to inches if needed by dividing result by 2.54.

This is for males only.

(Katch BMR-5-(10*kg)+(5*age))/6.25

[LZeeW]

I like the idea of "tweaking" your height in your profile until the Fitbit numbers match your biometric derived numbers.  It would change with any weight change in a predictable way.  I was going to suggest it, but I was afraid you might think I was a little nutty.  This might be the suggestion you were looking for all along.

A lot of people like to dismiss Harris-Benedict because it was derived in 1919.  But it is still used in current clinical studies.  In my readings about Mifflin, I came across a comment that it "better represents" our current lifestyle.  But that was under a heading that said that Mifflin is better for overweight and obese individuals.  Everything I find about Katch and Cunningham says they are best applied to very athletic individuals with very low % body fat and mugh higher than average muscle mass.  The fact that there are about 140 equations for BMR and RMR tells us that there is no single best answer.

If we asked Fitbit what they use, I would't be surprised if we get the answer I often get when I ask these types of questions -- it's proprietary.

[Heybales]

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@LZeeW wrote:

A lot of people like to dismiss Harris-Benedict because it was derived in 1919.  But it is still used in current clinical studies.  In my readings about Mifflin, I came across a comment that it "better represents" our current lifestyle.  But that was under a heading that said that Mifflin is better for overweight and obese individuals.  Everything I find about Katch and Cunningham says they are best applied to very athletic individuals with very low % body fat and mugh higher than average muscle mass.  The fact that there are about 140 equations for BMR and RMR tells us that there is no single best answer.

If we asked Fitbit what they use, I would't be surprised if we get the answer I often get when I ask these types of questions -- it's proprietary.

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They used to state they used Mifflin, then FAQ said WHO formula, now I can't find reference.

It seems to match the Mifflin for any I've asked to check.

Mifflin has been found in studies to be about 5% more accurate than Harris, and indeed scale better for overweight.

Neither have anything to do with lifestyle, since it doesn't include lifestyle.

Now, Harris also had the TDEE formula you see in TDEE tables, also based on that 1919 study, but I've never seen a Mifflin equivalent to that. Most sites will use that same ancient TDEE table with whatever you select as starting BMR formula.

The majority that's I've seen get RMR tested along with good bodyfat measurement, shows the Katch is good for overweight too.

Because those formulas are based on healthy weight and average ratio fat:muscle participants in the studies.

Mifflin helps out more for accuracy when you start adding more fat mass to ratio, but even there seen 200-400 inflated figures. Harris was 400-800 inflated.

Katch BMR if anything will slightly underestimate when overweight. Since it too was study using average ratio folks, it figures if low LBM than low BMR, but with more fat to muscle ratio, and fat does have energy needs, it's slightly underestimates. Whereas it seems the others are more than slightly overestimating.

But indeed, unless there is a difference of 200-400 in BMR, probably not worth messing with.

[slysam]

I am pretty sure Fitbit uses Mifflin. The reason I say that, if I leave my fitbit on a table all day (with calorie estimation disabled--a key detail for this test) then my fitbit calorie burn is 2 calories less than my Mifflin BMR. I've done that a couple times at slightly different weights. My Harris-Bennedict BMR is considerably higher than Mifflin (I think it was something like 130-150 or so higher than Mifflin). My Katch BMR comes out a little higher than Mifflin but lower than Harris. Though I am not sure of my current body fat percent, that was based on when I had the opportunity for a free bodpod measure. Sorry this has nothing to do with the original topic, but just saying why I am pretty sure it is Mifflin Fitbit uses. And that seems to be the more conservative of the common three estimates for me. 

About changing height to alter BMR... I would suggest this only if you calibrate your stride length for both walking and running (if you never run use a brisk walk in place of the running stride). Fitbit does use height in the deault guesstimate of your stride length so changing height will effect distance and also BMR stats (if you care). 

[Heybales]

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@slysam wrote:

I am pretty sure Fitbit uses Mifflin. The reason I say that, if I leave my fitbit on a table all day (with calorie estimation disabled--a key detail for this test) then my fitbit calorie burn is 2 calories less than my Mifflin BMR. I've done that a couple times at slightly different weights. My Harris-Bennedict BMR is considerably higher than Mifflin (I think it was something like 130-150 or so higher than Mifflin). My Katch BMR comes out a little higher than Mifflin but lower than Harris. Though I am not sure of my current body fat percent, that was based on when I had the opportunity for a free bodpod measure. Sorry this has nothing to do with the original topic, but just saying why I am pretty sure it is Mifflin Fitbit uses. And that seems to be the more conservative of the common three estimates for me. 

About changing height to alter BMR... I would suggest this only if you calibrate your stride length for both walking and running (if you never run use a brisk walk in place of the running stride). Fitbit does use height in the deault guesstimate of your stride length so changing height will effect distance and also BMR stats (if you care). 

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Thank you for remembering the change to stride length, totally forgot that, and so important.

Another way to see what Fitbit is using for BMR perhaps tad easier.

Look at your calorie burn chart at the 5 min blocks of time sleeping or any non-moving time really.

That cal/min divided by 5 x 1440 is the BMR they calculated.