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WHAT CAUSES OBESITY?
Genetic predisposition
Many studies have found a genetic link to obesity, showing that the
pattern of deposition of fat - i.e. the way fat builds up around the
body - and the degree of obesity can both be inherited. Other research
has shown that often normal-weight children of obese parents have a
lower resting energy expenditure - metabolism - than normal-weight children
of non-obese parents. Again, this suggests that the susceptibility to
obesity can also be inherited. But the fact that obesity has increased
so much in the last few decades appears to discount genetics as the
main cause.
Eating behaviour and obesity
The average UK diet tends to overload on saturated fats and refined
carbohydrates. Excessive sugar is often seen as linked directly to obesity
but it is often found in combination with fat in foods like biscuits
and sweets, so it might be that this combinationt is responsible for
weight gain rather than only the sugar.
Energy expenditure and obesity
Obese people tend to take far less exercise than others. But it's open
to question whether this is because they are obese - i.e. their movement
is restricted - or whether it is the cause of their obesity. Either
way, the lack of physical activity has a key role in obesity.
Many social and cultural factors are behind this general decline in
activity. Leisure pursuits are increasingly geared towards the sedentary,
with the explosion in computer games and rising dependence on television
for entertainment. Some studies have shown that the average child in
the UK walks a total of 30% less now than they did 30 years ago. Link
to Eufic article
The role of hormones and psychological influences
A small minority of cases of obesity can be explained by glandular problems.
These include clinical hypothyroidism, where there is not enough thyroid
hormone to control normal rates of metabolism.
They also apply to Cushing's Syndrome, where the production of the corticosteroid
hormones is abnormal. Steroids when prescribed (eg. asthma) can also
cause an increase in weight which is due to retention of body water.
This could be mistaken for 'obesity' if not looked into.
Sex hormones can also affect obesity. In women, body fat levels during
adolescence, pregnancy and the menopause are determined by the balance
of female sex hormones. Changes in energy intake, desire for food and
specific cravings occur at various stages of the menstrual cycle. Some
women appear to be more susceptible than others to hormonal changes
and many overweight women cite pregnancy as the time when their problem
started.
But lifestyle changes after childbirth could play an important part
in women's food intake too. So-called 'comfort eating' is prevalent
among the obese, i.e. when people respond to difficult emotional or
social situations by eating. However, it is by no means confined to
the overweight. Again, this points to a susceptibility in some people
but not others.
If you give up smoking, can you become obese?
Many people put on 10-15 kg when they give up smoking. This is because
their appetite
tends to grow and their metabolic rate tends to fall once they quit.
The weight increase is easily preferable in health terms to the dangers
of continued smoking, that is, of course, if it is not excessive.
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