Obesity - a
global epidemic
Obesity/overweight
in adults and children is becoming a worldwide health problem and the incidence
has increased markedly over the past decade. The World Health Organisation
recognises obesity as a global epidemic and it is now regarded as a disease. It
is estimated that 97 million or 55% of the
Obesity
is defined as a Body Mass Index (BMI) (body weight in kilogram divided by the
square of height in meters) equal or more than 30. Overweight individuals have a
BMI of 25 to 29. Hypertension, elevated cholesterol and Type II diabetes is more
common in overweight individuals than in the normal population and they also
experience more arthritis and joint and mobility problems. The so-called
metabolic syndrome with increased risk for heart attacks due to increased
accumulation of fat in the abdomen, resistance to insulin and low HDL (good)
cholesterol are also more common in obese individuals. There is some indication
that the immune system may also be altered, which make obese individuals more
susceptible for infection and disease. Obese adolescents may develop a negative
self-image, which could persist into adulthood.
The
increase in obesity rates has been attributed to the increased availability of
food with a high caloric content and a decreased level of physical activity.
Fast food, soft drinks, television and computer games are implicated as causes.
When energy expenditure is less than intake, energy will be stored as
triglyceride in the adipose (fat) tissue. Leptin (a hormone) secreted by the
adipocyte (fat cell) controls food intake by stimulation receptors in the
hypothalamus informing the brain of the fat store level and via the secretion of
other hormones control appetite. Other hormones identified in this regulation
are neuropeptide Y, ghrelin, insulin and cholecystokinin. A leptin deficiency
could be the cause of obesity. The so-called Syndrome X. Research has suggested
the involvement of genetic factors in the susceptibility to the development of
obesity with convincing evidence from twin studies by comparing identical twins
to non-identical twins. A lot of research on this subject is currently
undertaken and hopefully would give insight into new therapies for controlling
weight gain.
Obesity
is some of the cardinal features of numerous genetic syndromes (at least 25) of
which Prader-Willi syndrome is one of the commonest with an incidence of 1 in 20
000. Other syndromes identified and genetically mapped are Cohen (short stature,
large central incisors), Alström (blindness, deafness and diabetes) and
Bardet-Biedl (blindness and extra fingers and toes) syndromes. Other medical
causes are hypothyroidism (under-active thyroid gland), a growth hormone
deficiency and brain lesions involving the hypothalamus and pituitary gland. It
might also be due to certain drugs such as steroids (cortisone) or chemotherapy.
If a medical cause is suspected a specialist medical professional and a
dietician should address the problem. Medical causes however are the minority
and the most causes are due to excess behavioural and social energy intake
associated with reduced energy expenditure.
The
management consists of caloric restriction (diet), physical activity, lifestyle
changes and behavioural therapies as in Prader-Willi syndrome. Prevention
however is better than cure and adequate information should be given to families
regarding the risk factors for obesity and the preventative strategies.
References:
1.
Reuters Health Information 2004.
2.
Endocrinology and Metabolism Clinics of North America 1996/2003.
3.
Nelson’s textbook of Paediatrics.
4.
Nursing Standard Jan 2004.
5.
Circulation Sept 2003