Correlating Calories Difference & BMR

[ioncube]

I have calculated my Basal Metabolic Rate b/w 1820 - 1920 kCal using Harris-Benedict formula. Now I need to use this information mathematically. 

In the image below my Cals left are about 1k far lower than BMR calculated. Does this mean if I carry on like this for a month weight loss is sure to occur? Am I comprehending this math correctly

 

[JohnnyRow · Accepted solution]

Without analyzing your particular case, 2 suggestions regarding BMR:

1.  Check what Fitbit is using for your BMR.  Look at your calorie burn chart for overnight when asleep.  Get the reading of calories burned in 15 minutes when at the minimum and extend for 24 hours.

2.  When looking at on-line calculator, make sure you are really getting BMR, not estimated TDEE (total daily energy expenditure).

[Heybales]

Just FYI - Harris BMR formula from a 1919 study has been updated by several other studies since then, Mifflin is one similar to what Fitbit appears to use for BMR.

I agree with JohnnyRow you are probably not talking about BMR anyway, but TDEE.

Which is also a tired formula from the 1919 study being used.

But why calculate your TDEE from 5 activity options that are only about exercise but no differences to daily life, and hope you guessed right - when you have Fitbit on you estimating from actual movement and HR what you burn each day?

But to your question yes - if you ate less than you burned you would lose weight.

Make it extreme (like for 1000 cal deficit - you do have over 50 lbs to lose to healthy weight?) and make it fat and muscle mass.

Make it reasonable (less deficit when you have less fat to lose) and you can make it only fat weight.

Extreme diets are in the 80% failure rates to reach or maintain goal weight - don't recommend that route unless you enjoy doing this yearly as an activity.

And with losing muscle, makes it harder each year.