(5) Obesity and measures of obesity
(a)
Introduction
(Remember
obesity is only one measure of healthiness and well-being)
(see also on
health 4 page on
noncommunicable diseases page
If you consume more
energy rich foods from your diet than your body uses, your
body will store the excess energy rich foods as fat, hence
you put on weight.
If you body weight is over 20% than the
recommended weight for your height, you are classed as
clinically obese.
Obesity can result in health problems
including diabetes, high blood pressure and heart disease.
There is no such thing as
the 'perfect weight', we come in all shapes and sizes, but
there are limits within which we should be to be healthy!
In the medical
profession, a doctor can't just simply say that somebody is
overweight, without reference to some kind of statistical
index, usually by one/both of the ratios described below.
Equally healthy people
can have quite different weights, but there are some
reasonably good indicators as to when your weight is not
what it should be 'ideally'.
In rich developed
countries we are often dealing with 'overweight' people
eating too much rich fatty food, but in poorer
underdeveloped countries we are dealing 'underweight'
people, particularly young children suffering from
malnutrition.
Malnutrition means
lack of proper nutrition, caused by not having enough to
eat, not eating enough of the right things, or being unable
to use the food that one does eat.
(b)
The Body Mass Index
The body mass index is a
'rough' guide to help the medical profession decide whether you
are underweight, normal, overweight or obese - based on your
height and height.
The higher your BMI the more
fat you are carrying - but not necessarily unhealthily.
Body Mass Index (BMI) =
(body mass in kg) / (height in m)2
When measured, you then
consult a table of BMI values to se where you fit in!
Table of BMI values (from
https://www.vertex42.com/ExcelTemplates/bmi-chart.html)
| Body mass index |
Weight description |
| less than 18.5 |
underweight |
| 18.5 to 24.9 |
normal |
| 25.0 to 29.9 |
overweight |
| 30.0 to 40.0 |
moderately obese |
| over 40.0 |
very obese |
If you eat too much fatty
sugary foods and don't take enough exercise, most people will
put on weight and too much of it. You are taking in too much
energy rich food for your daily needs.
The excess energy releasing
food is stored as fat and gives you a raised BMI value.
Having a higher than normal
BMI value increases your risk of developing type 2 diabetes.
The BMI calculation is easy e.g. for a person with a body
mass of 70.0 kg and a height of 1.80 m,
The BMI = m / h2 = 70 / 1.802
= 21.6 (3
sf, kg/m2), suggesting the person is 'normal'.
Note of caution: Having a
high BMI is not always unhealthy e.g. athletes train hard to
build up extra muscle which is heavier than fat, so they will
tend to have higher than 'normal' BMI values and would not be
classed as overweight.
Note from 2020 on the covid-19 flue pandemic:
Research has shown that obese people are more likely to be
seriously ill with the virus than non-obese people - more
severe fever, more likely to be hospitalised and more likely
to die!
The waist-to-hip ratio should also be taken into
consideration (see below).
(c)
The waist-to-hip ratio
Where the body stores fat
is quite important.
If a lot of fat is stored
around the abdomen you get a 'fat tummy' and this is associated
with an increased risk of developing type 2 diabetes - hence the
importance of diet and exercise.
Comparing the circumferences
of waist and hips is another measure of whether you are
'overweight' and concentrates around one area where we can
accumulate to much fat - the 'tummy'.
waist-to-hip ratio = circumference
of waist
(cm) / circumference of hips (cm)
The higher your waist-to-hip ratio the
more fatty tissue you are carrying around the middle of your
body.
When measured, you then consult a table of
BMI values to se where you fit in!
Table of waste-to-hip ratios (from
https://www.healthline.com/health/waist-to-hip-ratio)
| Health risk |
waist-to-hip ratio (women) |
waist-to-hip ratio
(men |
| low |
less than 0.81 |
less than 0.96 |
| moderate |
0.81 to 0.85 |
0.96 to 1.00 |
| high (overweight) |
over 0.86 |
over 1.00 |
The Waist to Hip calculation is easy e.g. for a woman
of waist measurement of 32 cm and a hip measurement of 40 cm,
The waist to hip ratio = 32 / 40 = 32 / 40 =
0.80 (3 sf, no units), suggesting the person is 'fine'
(borderline low-moderate).
If you are female and
your waist-to-hip ratio is over 0.86 you are classed as
overweight.
If you are male and your
waist-to-hip ratio is over 1.00 you are classed as
overweight.
If you are above the
moderate waist-to-hip ratio values you are carrying too much
fat around your 'middle' - referred to as abdominal obesity.
Having a higher than
normal waist-to-hip ratio increases your risk of developing
type 2 diabetes.
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