WEIGHT REDUCTION
or ulcers on the skin; and damage to the
heart muscle, w hich may be fatal.
w e ig h t
The heaviness of a person or object. In
children, weight is routinely used as an
index
of growth.
In healthy adults,
weight remains more or less stable if
dietary energy intake matches energy
expenditure
(see
m e t a b o lis m ).
W e ig h t
lo s s
or weight gain occurs if the net bal-
ance is disturbed.
WEIGHT ASSESSMENT
One method of assessment is to use
the
b o d y m a s s in d e x
(BMI, or Quetelet’s
index), obtained by dividing weight
in kilograms by the square of height in
metres.
2 0 - 2 5
kg /m 2 is considered to
be a healthy weight; a score of greater
than
2 5
, however, may indicate that
a person is overweight (see the accom-
panying table).
However,
BMI
has
its
limitations
when assessing whether a person is
medically overweight or underweight: a
person with a good muscle bulk may
have a high BMI but a healthy body
composition;
a
small-framed
person
with a lot of body fat may have a nor-
mal BMI. For this reason, assessment of
the percentage of a person’s body fat
gives a more accurate idea of healthy
versus unhealthy weight. Distribution
of body fat is also important: people
with central obesity
(measured by a
high waist:height ratio) are considered
to be less healthy than those with a
more even distribution of fat.
In children, weight can be compared
with standardized predictions for age,
w hich differ according to the gender
and race of a child. Such weight charts
are used to assess how well a child is
thriving. At all ages, divergence from
standard figures (either using BMI or
body fat percentages) may have medical
implications. If an individual is found
to be “underweight” , their
n u tritio n
may
be inadequate as a result of a poor diet
or disease; if an individual is signifi-
cantly “ overweight” , he or she may be
suffering from
o b e s it y
.
w e ig h t lo s s
Any time that there is a decrease in
energy intake compared with energy
expenditure, weight loss is likely to
occur. The decrease may be the result of
deliberate
w e ig h t re d u c tio n
or a change
in diet or activity level. Weight loss may
also result from fluid loss (for example,
because of sweating in a hot climate) or
it may be a symptom of a disorder.
Unexplained weight loss should always
be investigated by a doctor.
LOSS OF APPETITE
Many diseases can disrupt the appetite
to the extent that an individual loses the
desire to eat, w hich in turn leads to
weight loss. Loss of appetite may also be
a sign of generalized ill health.
D e p r e s -
s io n
reduces a person’s motivation to
eat;
p e p t ic u lc e r
causes pain and, in some
cases, food avoidance; and some kidney
disorders cause loss of appetite due to
the effects of
u ra e m ia
(raised levels of
the waste product urea in the blood). In
the
conditions
a n o re x ia n e rv o s a
and
b u lim ia ,
complex psychological factors
affect an individual’s
eating
pattern,
sometimes with dramatic results.
DIGESTIVE CAUSES
Digestive disorders, such as
g a s t ro e n t -
e r it is
,
lead to weight loss as a result
of vomiting or diarrhoea. Weight is also
affected by cancer of the oesophagus
(see
o e s o p h a g u s , c a n c e r o f
) and
s to m a c h
c a n c e r
.
M a la b s o rp t io n
of nutrients in cer-
tain disorders of the intestine or the
pancreas also affect weight.
METABOLIC CAUSES
Some disorders cause weight loss by
increasing the rate of metabolic activity
in cells. Examples are any type of
c a n c e r
,
chronic infection such as
t u b e r c u lo s is
,
and
h y p e rt h y ro id is m
(overactivity of the
thyroid gland). Untreated
d ia b e t e s m e lli-
tu s
may also cause weight loss.
w e ig h t re d u c tio n
The process of losing excess body fat. A
person who is severely overweight (see
o b e s it y
) is at an increased risk of devel-
oping various illnesses, such as
d ia b e t e s
m e llit u s
,
h y p e rt e n s io n
(high blood pres-
sure), and heart disease, so a weight loss
programme is a good idea to reduce the
risk of developing such conditions.
HOW IT IS DONE
The most efficient way to lose weight is
to eat a healthy balanced diet (see
n u t r i-
t io n
).
This may involve a reduction in
the intake of excess calories (those that
are over the recommended daily lim it),
combined with regular exercise, both
a e ro b ic
(fat-burning) and toning (mus-
cle-building).
Motivation,
emotional
support, and exploration of the psycho-
logical factors affecting eating are also
important factors for success.
DRUG TREATMENTS
In most circumstances, drugs play little
part in a weight-loss programme. How -
ever,
o rlis ta t
(an antiobesity drug) may
be a useful adjunct to a reduced diet,
and they may, in some cases, be appro-
priate for those individuals who have a
high
b o d y m a s s in d e x
.
A p p e tite s u p p r e s -
s a n t s
that are related to
a m p h e t a m in e s
are not recommended.
WEIGHT/HEIGHT GRAPH FOR MEN AND WOMEN
To find out whether or not you are underweight, normal weight, or overweight,
first find your height, then run your finger up to your present weight. People with
a BMI of 20-25 kg/m2 are considered to be a healthy weight; those whose BMI is
greater than 25, however, may be considered to be overweight.
Weight
lb
kg
210
95
90
85
80
75
70
65
200
190
180
170
160
150
140
Overweight
BMI over
25
Healthyweight
BMI 20-25
BMI under 20
130
60
120
55
110
50
100
45
90
40
144146148 150 152154 156 158 160162164166168170 172174 176 178 180182184186188190192194
He №
cm
' i ' 11
1
'i ' i ' i1
1
'i ' i '
i1
'i
' i ' i1
1
'i ' i '
i1
1
'i ' i '
57
58 59 60 61 62 63
64 65 66
67 68 69 70
71
72
73
74
75
76
W
803
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