I usually see this abbreviated as BMR. For those just tuning in, that’s basal metabolic rate – the number of calories you’d burn per day if you never got out of bed. The standard formula is:
where m is your mass in kilograms, h is your height in centimeters, a is your age in years, and s is 1 for male, 0 for female.
My understanding is that fitness trackers / smartwatches use that formula for BMR and then estimate active calories from heartrate and movement. I posted about the discrepancy between Fitbit and Garmin in that regard the other day: Garmin is very stingy with burned calories compared to Fitbit
It’s very possible that fitness trackers are failing to account for fidgetiness, unless that manifests as a slightly higher heart rate. I need to look into this more as well.
I’m still thinking about the rest of this but am very intrigued; it’s very related to what we’re doing in Mindful Munching w/ Metrics right now.