All siz
B
ody mass index (BMI) is used as a
measure of ‘fatness’ by health
professionals, insurance companies
and anyone with a calculator. The
category someone falls into, when
their BMI is calculated, is broadly
interpreted to correspond with risk factors for
diseases such as diabetes, heart disease and even
cancer. When I was studying health science at
university I was taught to incorporate this measure
into my case-taking, when I would glean important
information about a person’s health and risk of early
mortality. How nifty that with only two numbers
(height and weight) we could categorise a person as
normal, overweight or obese. Fast forward to a
real-life clinical setting, and it didn’t take me long to
realise the BMI wasn’t the tool it was made out to be.
If I’d known the history of the science behind
the BMI I’d have questioned its validity much
sooner. It was devised by Belgian mathematician
and statistician Lambert Quetelet in the 1830s, but
Quetelet himself warned of the dangers of
extrapolating health predictions using his simple
graph. Perhaps he could see the inherent problem
in using such limited data to predict risk factors for
serious diseases. It’s stunning that almost 200 years
on, given all that we have learned about health and
body composition, that we still see the BMI being
employed as an absolute measure of health, and
that we’ve been conditioned to think of it as
independently significant.
So why are we still using the BMI? It seems the
answer is convenience. It’s easy and it’s fast. It’s also
been ingrained into many institutions as a way to
categorise people. Public health systems often use it
to exclude people from surgery eligibility or
procedures. It’s often used to deny funding for
fertility treatments. Insurance companies often use
the BMI to assess a client’s premiums and use it to
explain higher premiums in some cases. BMI has
even been cited recently as the reason for denying
at least two ‘skilled worker’ visas for New Zealand.Remembering that the BMI system was conceived
by white Europeans for white, middle-aged
Europeans, it’s easy to see how problematic its
widespread use could be. Little variability is allowed
for in terms of ethnicity and different body shapes.
Even age isn’t taken into account, unless the person
is under 20, in which case another model is used.
If we’re not careful, it can be a way to use our
weight against us – something we’re already pretty
good at as a society. There is no doubt that some
people’s health is negatively affected by the pressures
of a larger body, but it turns out that the BMI is not a
helpful measure to promote wellbeing in these
people. For others, a higher than ‘normal’ BMI has no
bearing on their risk factors for disease. Other, more
useful measures should be used for everyone who is
seeking help. The results of a BMI ‘test’ can
misinform people about their true body composition,
leading to misguided changes in behaviour driven by
fear. Not to mention that it could contribute to body
dysmorphia and other body-image issues.
It also seems that by putting BMI above all else,
we’re severely underutilising the advances of the
last 200 years. We can and should be doing better by
our patients. A guiding principle of naturopathy is
to ‘treat the individual, not the disease’. This means
taking into account all the pertinent information
about a patient, from family history through to
mental health, physical activity and nutrition. Lab
test results and any other numeric snapshots are
also very important within the context of a person’s
full health story. It’s a holistic approach we’ve lost
the art of with the rise of medical specialisation. Of
course everything has its place, but I see a yearning
among patients to be considered more fully as
individuals and less like a dot on a graph. We know
better – it’s time to do better!
When it comes to health, it’s not good enough to
blindly use a system we know to be flawed. As
individuals, parents and patients, let’s demand a
deeper conversation about health. One that’s not
limited by our height and weight.BYE BYE, BMI
ANNALIESE JONES, NADIA NATUROPATH AND MEDICAL HERBALIST, EXPLAINS WHY
WE NEED TO RETHINK THE BODY MASS INDEX AS A MEASURE OF HEALTHannaliese.healthcare @annaliese.healthcare @annaliesejonesnaturopath