DonAithnen (donaithnen) wrote,

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"We get a lot of email about this"

So it seems part of the reason that i was getting confusing answers for my BMR is that there are actually two different BMR formulas, and despite the fact that the newer and better one (MD Mifflin and ST St Jeor) was created "recently" in 1990, most sites that calculate it for you use the older formula (Harris and Benedict.) In order to resolve this "problem," apparently the new formula is referred to as the RMR or "Resting Metabolic Rate."

So according to the calculator on this site (which seems to be the most informative in regards to this issue that i've found so far) i had a BMR of 2042 and RMR of 1904 at 210 lbs, and at 200 lbs it's now a BMR of 1979 and RMR of 1858. The RMR figures match what i get plugging in the numbers for the equation from wikipedia, so that's good.

So if i use the 1.2 activity level ("Little or no exercise and desk job," which despite intermittent bouts of rollerblading and dancing describes me most of the time) then my adjusted BMR is 2375 and adjusted RMR is 2230.

However on the earlier information page it says "if you are looking for an estimate of how many calories you need or burn in a day, we suggest that you not use BMR or RMR at all. We suggest that you calculate the actual activities that you perform in a 24 hour period as described in Calculating Daily Calorie Needs."

Okay, i'm willing to try that, so i came up with the following theoretically average schedule and results from plugging it into their activity calculator as described:

Sleeping - 572 calories in 7 hr
Showering (self care) - 91 calories in 30 min
Dressing and Undressing - 91 calories in 30 min
Driving - light vehicle (e.g., car, pick-up) - 181 calories in 1 hr
Computer Work (typing) - 1,157 calories in 8 hr 30 min
Walking - 2.5 mph - 68 calories in 15 min
Eating - sitting - 68 calories in 30 min
Computer Work (typing) - 408 calories in 3 hr
TV - watching - 159 calories in 1 hr 45 min
Reading - reclining - 91 calories in 1 hr

Which all looks okay in theory, until it gets totaled up as:
Total: 2,886 calories in 24 hr

Um, wait, my sedentary 1.2 life style is supposed to be about 2230 based on my RMR, how does adding up the elements of such a lifestyle result in a theoretical 2886 calories?

In fact, let's test the most sedentary life possible outside of being independently wealthy, a telecommuting techie who does nothing but lie in bed reading the rest of the day.

Sleeping - 653 calories in 8 hr
Computer Work (typing) - 1,089 calories in 8 hr
Eating - sitting - 68 calories in 30 min
Reading - reclining - 680 calories in 7 hr 30 min

Totals: 2,490 calories in 24 hr

So even a bare minimum lifestyle is 260 calories over the sedentary 1.2 activity level. Clearly the math is kind of wonky somewhere.

They do have an entire page about the accuracy of the calculator which discusses a lot of issues, though not specifically why a minimum amount of activity results in a calories use higher than a 1.2 activity level.

However i was very amused by the following tidbit :)

"In addition, we believe that the METs assigned to a few of the activities are either too high or too low. We originally assumed that some activities had been assigned very low METs because they were based on a period of time that included periods of rest. For example, in Gymnastics a notable amount of time is spent resting and waiting ones turn to perform; in Surfing much time is spent waiting for a good wave. This could explain why these activities have been assigned the same MET as Bakery Work which is much less strenuous but is performed on a continuous basis.

Perhaps similar logic applies to Sexual Activity - Vigorous, which has the same MET as Sewing and Knitting. We get a lot of e-mail about this."

In any case, it's clear that the low end of my scale should probably be somewhere between 1858 and 1979 calories (so 1918 for today is right on! =) That's a negative calorie expenditure of somewhere between 372 and 1028 calories, depending on which set of math you want to believe.

And in a totally random coincidence, patrissimo just posted a link to an article claiming that occasional binges while dieting, in particular high carb binges, are good for you. This fits rather well with my philosophy that all things should be taken in moderation, including moderation :)

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