direct calorimetry - calculating BMR

A

aw202

New Member
hey guys.

i just bought myself a basal thermometer and have been checking my temp every morning upon waking. i wanted to check out if my metabolism had slowed down due to heavy cal cutting. does anyone know of a formula that converts my basal temp to my basal metabolic rate? i.e. how many calories my body needs to stay alive? i've used the oversimplified formula in the past where you multiply your weight in kgs by 24. unfortunately that doesn't take into account your resting temperature, which is a better guage of your BMR. i'm thinking that there should be a conversion from your basal body temperature. i've dug all over the net and haven't found anything.

there's this nifty device under research that seems to use a similar method. it uses your metabolic rate as a function of body temperature and body surface area. it basically calculates the thermogenic output of your body by estimating how much heat you are giving off through you skin.

check it here:
http://www.direct-axis.net/LifeChekWeb4/htdoc/TechnologyPage.html

Bryan, is this stuff that you've read up on before? i'm asking cuz i know you dabble in a lot physiology research journals.
 
No, temperture isnt a very good guide to metabolic rate, the only decent way is to measure it via direct or indirect calorimetry.

There is a nifty wee device that is for sale now, around 1500US, that you just put in your gob and breath in it for 10 mins or so, and it estimates BMR (or whatever you are doing at that point). But temperture is pretty rubbish (in reality you would need core body temp rather than skin temp anyway - how far do you want to stick the thermometer)

Actually going off on a tangent, they did a pile of cycling studies where they measured core temp by a rectal thermometer. I wanna know how well you would cycle with a thing up your butt.
 
hahaha aaron!

i'm not about to exercise with anything up my butt! that baby is a one way only street. this is what i'm getting at tho; there are several components to your calorie expenditure during the day:

Basal Metabolic Rate: the amount of energy needed at rest to maintain basic physiological functions like heartbeat, breathing, muscle function, keeping the brain alive (this is the component i'm trying to figure out as it accounts for 60-70% (?) of your daily cals)

Thermic Effect of Exercise - energy needed to perform physical activity (i think this might be measured via VO2 or indirect calorimetry... OR sticking a thermometer up one's rectum)

Thermic Effect of Food - amount of energy needed to digest, store, and metabolize nutrients (this is why we want to eat 6 small meals as opposed to 3 big ones. we get a rise on this one with frequent feeding)

Adaptive Thermogenesis - amount of energy needed for shivering, sweating

Essentially, I'm trying to get to a reasonable calculation for the BMR component of our total calorie expenditure. I thought that basal body temperature was a good proxy for this. I was measuring with a thermometer under my tongue, all the way back against my bottom gums. That is supposed to be the warmest part of your mouth. No rectum for me thank you. I wouldn't be able to ever put that bad boy back in my mouth again.

I came across a formula for BMR calc called the Harris Benedict Equation:
(13.75)(Weight in kgs) + (5.0)(Height in cm) + (66.47) - (6.76)(age)

Again, I felt that this was lacking because of the termperature component. I guess it takes into account fat content and body surface area (estimated both from height and weight), but then again, it might going at it from a completely different angle.
 
Try this
on my webpage I have a excel spreadsheet called rmr.xls
Here
It contains a number of RMR estimates available, so you can work it out there. As you can see, they all fall within 100-200kcals of each other. I usually use the average as a persons estimated rmr.
 
I like that one, Aaron - saving it
thumbs-up.gif
 
[b said:
Quote[/b] (aw202 @ Mar. 06 2003,12:05)]i.e. how many calories my body needs to stay alive? i've used the oversimplified formula in the past where you multiply your weight in kgs by 24.
Click to expand...
According to that I should be dead!

My weight 72x24=1728

I have been eating ~1600 while dieting. That is also training 3xweek (HST & bag work). No detectable muscle or strength loss.

Aaron, I cant access your spread sheet. I am 'forbidden'! Can you turn off the Elf Alarm :D
 
Weird, I have no idea why you can access it. maybe internet settings dont allow you to access a site with 3million popups? You get what I pay for (nuttin :) )

Click on the email Icon and send me a message and I will send it thru 2 u
 
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