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0:00
Hello, my name
is Dr. Andrew Walley.
I'm senior lecturer
in Human Genomics
at St. George's University
of London,
and I am going to talk to you about
how we define obesity.
0:10
In summary, I'm goint to talk
to you about measures of obesity
and the body mass
index specifically,
how we define obesity using BMI.
The current population
trends in BMI,
so that you can see
the global problem of obesity.
The drawbacks of using BMI
as a measure of obesity,
and the other measures
that are available to us
within the field of obesity
for measuring.
0:32
So how can we measure obesity?
Well, the most obvious
would be by weight,
but you will see in a little while
that body mass index
is a preferred measure.
Alternatives
such as waist/hip ratio are used,
and then we start moving
into more accurate measures
but more time consuming measures
like skinfold thickness,
impedance, air displacement,
and imaging.
And I'll talk to you about
all of those later on.
0:59
Why do we choose BMI?
The main reason we choose BMI
is because it's appropriate
for large scale
epidemiological studies.
It can be measured very quickly,
it's relatively reproducible,
and most importantly it requires
no expensive equipment.
In addition, most genetic studies
out there will measure
weight and height as part
of their basic measurements.
So those studies can be
incorporated into meta-analyses
of BMI giving tens of thousands
of subjects for analysis.
1:31
The body mass index
is relatively simple to calculate.
It's your weight in kilograms
divided by your height
in meters squared.
So for example,
I am 1.78 meters tall
and I weigh 90 kilos,
and that gives me a BMI
of 28.4 kilograms
per meter-square.
