Obesity is an excess
of body fat frequently resulting in a significant
impairment of health.
Adipose tissue is a normal constituent of the human body
that serves the function of storing energy as fat. The
fat may be used by the body in response to various
metabolic demands.The excess fat accumulation is
associated with increased fat cell size.A very
important reason for obesity is the overconsumption of
carbohydrates. When carbohydrates enter our body they are
rapidly broken down into glucose (a sugar). Glucose
raises blood sugar levels causing pancreas to make the
hormone insulin. Insulin inhibits fat already stored in
our body from being broken down and it also promotes the
storage of new fat in the body; and increases cholesterol
levels
In many forms of severe
childhood-onset obesity, the total number of fat cells is
increased.
Formerly, obesity was explained by
the single adverse behavior of inappropriate eating in
the setting of attractive foods. But now it has been
established that obesity has multiple causes and is of
different types. Both genetic and environmental factors
are likely to be involved in the pathogenesis of obesity.
These include excess caloric intake, decreased
physical activity, and metabolic and endocrine
abnormalities.
Genetic determinants can either
play a major role in the pathogenesis of obesity or
enhance susceptibility to its development. The conditions
in which genetics may play a role are Prader-Willi
syndrome, Ahlstrom's syndrome, the Laurence-Moon-Biedl
syndrome, Cohen's syndrome, and Carpenter's syndrome.
Over weight can be estimated by
Body mass index (BMI), which is weight/height square,where weight is in kilograms and height is
in meters.
Obesity is defined as a body mass index above 30
kg/square meter.
Weight gain may confer increased health risks even if the
BMI does not exceed 25. In women a weight gain of more
than 5 kg (11 lb) is associated with increased risks of
diabetes and heart disease, and in men any weight gain
after age 25 appears to carry increased health risks.
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