Is BMR a constant?

I generally waitress 5x per week and the shifts are between 6-7 hours depending on the day, on days that I don't waitress, is my BMR lower? For instance, would it make sense for me to adjust activity level to sedentary on my two days off (making my BMR around 1700) and readjust it to moderately active on the days that I work (making my BMR around 1950) or am I just totally wrong?

The BMR depends on your activity level so I think you have it figured out right there.  The days you have off if you aren't as active then you are burning less calories so you should have less during those days.

no, it's not a constant, but it's not going to fluctuate day to day, or even week to week.  it's also not a precise measure, and unless you've spent a significant amount of time in a metabolic chamber, it's just an estimate.

if you have a major career change, lifestyle change, hormonal shift, etc. it will change, but as far as the day to day stuff, the only way to really know your burn is to log every bite you eat and then see what happens with your weight.

Original Post by xxana:

I generally waitress 5x per week and the shifts are between 6-7 hours depending on the day, on days that I don't waitress, is my BMR lower? For instance, would it make sense for me to adjust activity level to sedentary on my two days off (making my BMR around 1700) and readjust it to moderately active on the days that I work (making my BMR around 1950) or am I just totally wrong?

You are confusing the burn meter with BMR.  They are not the same.  BMR doesn't take into account activity at all.  It is simply the amount of calories needed to keep your body functioning.  Your BMR does change however, based on weight loss or gain.  But as someone else commented, BMR calculations (where you just plug in variables like height, weight, etc) are just estimates and for people who aren't average (very tall, very short, very overweight) they can have a significant amount of error.

what is the difference between the burn meter and bmr then?

what techdog said - BMR is how much your body burns essentially in a coma - what it uses for fundamental functions like breathing and heart beating. Burn meter is how much you actually burn, by getting out of bed and walking around, and any other activities.