On 09-Feb-05 David Ives wrote:
> As a simplistic excursion from the main thread, can I ask what
> is the difference between using BMI and a height/weight chart
> (beyond the giving the relationship of height/weight a score)?
>
> I have recently seen examples of procedures where the BMI is
> the governing factor on the person's ability to carry out a
> particular job - surely this is nonsense? If we are going to
> use an indicator such as this for giving advice on fitness to
> work, we must look at the other factors mentioned previously,
> and include these in the decision making process (which I am
> sure most of us do!)
>
>
> David Ives
> GradDipPhys, MCSP
> WellWork Ltd
I don't think this is a "simplistic excursion". For one thing,
a height/weight chart, while essentially serving the same
purpose as BMI (delineating a "desirable" relationship between
weight and height):
a) Can be more flexible (literally) in that if you want to
you can put in wiggles and bends, while a formula such
as BMI = weight/(height squared) imposes a strict regularity;
b) Can more readily display "acceptability bands", and generally
allow a more elastic usage.
For another thing, the example David gives illustrates one of
the serious concerns I originally expressed:
"My concern derives from the blatantly prominent role
that BMI thus defined currently plays in discussions
of "healthy weight", obesity, cardiovascular risk, diet,
etc., to the point where draconian decisions (both for
individual patients and in published statistics about
the "health" of populations) are made on the basis of
its value."
Things like "procedures where the BMI is the governing factor
on the person's ability to carry out a particular job" are
very much the kind of "draconian decision" I had in mind!
Not that I'm advocating height/weight charts as the panacea
to cure the ills of BMI -- just as David says, there are other
highly relevant factors not dreamt of in H/W charts, let alone
BMI.
I'm inclined to put it down to a "check-list" mentality on
tha part of administrators, an avoidance of exercising those
faculties of discrimination which draw on different dimensions
of observation and knowledge (a.k.a. intelligence), this in
turn perhaps down to "Nobody ever got fired for using BMI"
whereas if you resourcefully look underneath the BMI but things
turn out badly then "you get fired and we get sued". If you
stick to the rules then you're OK; and the rules had better
be plain and simple so that it's not easy to misuse them.
I'm pleased to have drawn out what looks like an interesting
discussion, and look forward to seeing more of it.
Many thanks to all who have contributed so far. I'll be
particularly interested to hear more from people like Gwyn
Weatherburn who have contact with the (nowadays) obscure
historical origins of this measure.
Best wishes to all,
Ted.
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E-Mail: (Ted Harding) <[log in to unmask]>
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Date: 09-Feb-05 Time: 15:53:35
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