Thursday, July 20, 2006

BMI can BMA

"Two things are infinite: the universe and human stupidity; and I'm not sure about the universe." ~ Albert Einstein

'BMA' = Bite My Ass. Now that we have that cleared up I can tell you WHY.

The below chart was copied off the 'Health Canada' website:

Health Risk Classification According to Body Mass Index (BMI)
Classification BMI Category (kg/m2) Risk of developing health problems
Underweight <> Increased
Normal Weight 18.5 - 24.9 Least
Overweight 25.0 - 29.9 Increased
Obese class I 30.0 - 34.9 High
Obese class II 35.0 - 39.9 Very high
Obese class III >= 40.0 Extremely high

My 'BMI' is currently 33.1 which puts me well into the 'Obese class I'......which I agree with. However for me to reach a BMI of 24.9.... the maximum BMI in the 'Normal Weight' category I would have to weight only 173.5 lbs. To get to the middle point 21.7 BMI of the 'Normal Weight' category I would have to drop to 150.9 lbs. To get to the bottom edge of the 'Normal Weight' category I would need a BMI of 18.5 which translates into only 129 lbs.

How many "average" 5' 10" guys weight between 129 - 150.9 lbs? Bollocks.........who made this crap up? Why is this now the industry standard for measuring a healthy body composition? Surely measuring Body Fat% is a more accurate indication of a healthy body composition?

Lets take a look at my situation. Based on my current weight loss to BF% ratio, what would my Body Fat Percentage or BF% be at 190lbs: my BF% would be at:

Current Lbs lost = 7.2
Current BF% lost = 2.3%
Formula: Body Fat % lost divided by Weight lost = BF% lost per lb.
: 2.3 / 7.2 = .319

Current Weight = 235.8 lbs
Target Weight = 190 lbs
Weight Loss to Go = 235.8 - 190.0 = 45.8 lbs
Formula: Weight Loss to Go x BF% lost per lb = BF% lost to get to Target Weight
: 45.8 x .319 = 14.61% BF

Formula: Current BF% - BF% lost to get to Target Weight = BF% at Target Weight
: 33.1 - 14.61 = 18.49% BF
So the next question is.... what is a healthy BF% ? These days that's not an easy question to answer since everyone has gone BMI crazy.....But I was able to dig a few sources:

Obesity Canada states "The recommended body fat content for males is 15-18%"
Mens Health Magazine states that for men "(a) Healthy body composition can vary from 10 to as high as 25 percent fat, says Tim Lohman, Ph.D., a professor of physiology at the University of Arizona"

So based on the few sources I was able to locate a BF% of 18.49% seems to be about right. Ideally I would love to see my BF% around 14-16% when all is said and done.

Does anyone else have a problem with BMI......am I alone? I'm hoping someone else can shed some light on this topic. For now I'm going to leave my BMI stats on my sidebar until I think things through a bit more.

Update: July 24th, 06 @ 11:19PM - I haven't received any feedback yet....but I'm done thinking about this. Gonezo!

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3 Comments:

Blogger Kim Ayres said...

BMI is only ever to be taken as a rough guide. When England won the Rugby World Cup a couple of years ago, somebody pointed out that accrding to the height-weight charts, ever single member was at least obese class 1, yet there's not an ounce of fat on any of them.

Muscle weighs more than fat, so if you are fit, then you can expect to weigh more, yet look slimmer.

The variation also has to take into account body shape. for example, my stepson is 6 inches taller than me if we are standing up. But I have shorter legs proportionally. If we are sitting on a bench together then I am actually taller than him.

Now given that most of the weight is carried in the body rather than the legs, then a straightforward height-weight ratio isn't going to be accurate for the both of us

These tables have to be taken as a rough guide only and not the be all and end all of weight variations. My goal is to reach a BMI of 24 point something, but then to try and shape my body a bit.

8:11 AM  
Blogger Josh said...

I've got a friend who is a very accomplished natural bodybuilder. He's "overweight", and almost obese according to the BMI. This is at 10% bodyfat.

Yeah, BMA too. Which, by the way, is shrinking.

2:06 AM  
Anonymous Anonymous said...

"How many 'average' guys weigh between ...." - this is irrelevant as far as the health implications go.

The medical advice is based on what's healthy, not what's popular or common. Your justification basically runs to "Everyone is unhealthy so I will be to". Fair enough and you'll have lots of company in having an increased risk of heart disease, diabetes and so on.

7:20 AM  

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