Saturday, May 18, 2013

Metabolism and ditching the average

People who read my blog regularly know that I study a lot about metabolism and stuff like that because my system is pretty well messed up.

I thought I would talk about understanding individual metabolism today.

Metabolism is measured in milliliters of oxygen absorbed per kilogram.  The average is 3.5ml/kg.  I am beginning to think that number is something someone pulled out of the air, but, it is an accepted constant.

Here is a power point explaining METS and O2 and whatever.

I'll explain how I ditched the 3.5 constant and how I figured out my basic metabolic rate to use in calorie burning equations.

First, I kept an activity log.  I used a small notebook that fit in my pocket.

I recorded activity and food/calories and daily morning and evening weight.  I used my scale to measure foods because I wanted to make sure my calories were very close.  I did this for about a month.

Every day I used a set of tables at to estimate the average MET value.  Metabolic Equivalence Tables give us basic numbers that we can translate into how many calories we burn during an activity.

I added everything up and created an average MET for the day, including sleeping.

Once we have about a months worth of daily calories, weights and MET averages as long as our weight has been stable, plus or minus 1%, we can calculate an average metabolism.

Lets say my daily MET, including sleep, averages 1.1 (sedentary) An MET of 1.2 for 16 hours and an MET of 0.9 for 8 hours.

My typical weight over the month is 260lbs.

My daily caloric intake averaged 2400 calories (this is actually my target and it makes a nice round number for our calculations, real was a little less).

 The calculation is MET*3.5*(weight in kg)/(200/minutes) OR (in my case, calories per hour) MET*3.5*118/3.33333

3.5 is the average ml of Oxygen or O2 per kilogram.
3.33333 is 200/60

So we have an average MET of 1.1 (Mine was actually 1.36 but I am using 1.1 as an example) 1.1*3.5*118/3.33333 or 136 calories per hour or 3,271 calories per day.

"But, dude, you only ate 2400 calories and you didn't lose weight.  What is up?  Your math sucks"

Yeah, so obviously my metabolism isn't average and the 3.5 constant is wrong, for me.

Using some math magic called ALGEBRA we reverse the equation, 1.1*X*118/3.33333=100

The 100 comes from 2400/24 hours.

Using this calculation we end up with an average daily metabolic rate of 2.56.

But wait, my real MET average is 1.36 so the equation is really
or 2.07 milliliters of Oxygen per kilogram.

There is a gadget coming on the market called the Breezing at which will actually measure the amount of O2 and if I am able to afford it when it comes out I will check my calculations against actual readings.  Until then I just have to use my food intake, weight and activity to estimate my average metabolism.

Now I know my typical metabolic rate, not specific to any activity and for all I know those numbers do not apply to me either.  

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