BMR Question

[CarolS]

Is there a way to see what Fitbit has as my BMR?  

I keep an Excel spreadsheet with my weight, etc., and I also track my BMI and BMR.  I know the formulas to track both, but I'm just wondering how I can see what number Fitbit has come up with.

I know it sounds crazy, but sometimes I want to know, for example, how many calories I'll burn for the rest of the day if I do absolutely nothing.  Let's say, my burn per Fitbit at 5:00 PM is 1604 and I know my BMR is approximately 51 calories per hour.  I should be able to add 357 calories (51 x 7 hours left in the day) and that would give me a burn of 1961 calories for the day - again, assuming I was completely sedentary.

OK, I know I'm kind of obsessing, but I do love my Excel spreadsheets!

[RunnersHi]

I don't know the answer to this, but I'm interested in it too. When I look on my phone app, It has both an in/out meter and a calories left to eat meter. I'm on the 1,000 calorie deficit, so for example, today, I burned 2,416 calories and ate 1,330. I should only have (2,416-1,330-1,000) 86 calories left to eat, but it reads 449.

So, I'm assuming the 'calories left to eat' meter does include the calories I'll burn from my BMR for the rest of the night...is that what you do too?

[Dominique · Accepted solution]

Go to https://www.fitbit.com/activities and you will see the calories you burn per time slots of five minutes. Have a look at calories burned during your sleep. Unless your sleep is extremely restless, they should correspond to your BMR. For instance, it is 5 calories in my case:

 

There are 1440 minutes in a day (24 x 60 = 1440), which is 288 time slots of 5 minutes. Therefore my rough BMR would be 288 x 5 calories = 1440 calories.

If I use the Mifflin St Jeor formula (for instance, with this online calculator), my calculated BMR would be 1458 calories. Close enough, which is no coincidence, since Mifflin St Jeor is the underlying formula used by Fitbit (although this is not stated upfront anywhere).

The problem with using the activity bars in the Fitbit chart is that calories are expressed without decimals. If your actual calories burned in five minutes is 4.49, it will be rounded to 4, and if it’s 4.51, it will be rounded to 5. When you multiply by 288, you’re having a significant discrepancy. Bottom line: just use the Mifflin St Jeor formula, which will be more accurate. 

[CarolS]

Awesome!  Thank you Dominique!