What
is Obesity?
Obesity and overweight have in the last decade become a global problem -
according to the World Health Organization (WHO) back in 2005 approximately 1.6
billion adults over the of age 15+ were overweight, at least 400 million adults
were obese and at least 20 million children under the age of 5 years were
overweight.
Experts believe if the current trends continue by 2015 approximately 2.3
billion adults will be overweight and more than 700 million will be obese. The
scale of the obesity problem has a number of serious consequences for
individuals and government health systems.
Consequences and Health Risks
Obesity is a concern because of its implications for the health of an
individual as it increases the risk of many diseases and health conditions
including: -
·
Coronary heart disease
·
Cancers (endometrial, breast, and colon)
·
Stroke
·
Liver and Gallbladder disease
·
Sleep apnoea and respiratory problems
These conditions can cause or contribute to premature death and substantial
disability.
Cardiovascular disease - mainly heart disease and stroke
- is already the world's number one cause of death, killing 17 million people
each year and diabetes has rapidly become a global
epidemic - according to WHO projections diabetes deaths will increase by more
than 50% worldwide in the next 10 years.
Less common health conditions associated with increased weight include asthma, hepatic steatosis and sleep apnoea.
Economic Consequences
Overweight and obesity and their associated health problems have a
significant economic impact on health systems and the medical costs associated
with overweight and obesity have both direct and indirect costs - direct
medical costs may include preventive, diagnostic, and treatment services
related to obesity, while indirect costs relate to loss of income from
decreased productivity, restricted activity, absenteeism, and bed days and the
income lost by premature death.
Defining Obesity
Overweight and obesity are defined by the WHO as abnormal or excessive fat
accumulation that presents a risk to an individuals health.
Overweight and obesity are major risk factors for a number of chronic
diseases, including diabetes, cardiovascular diseases and cancer and while it was once an issue only in
high income countries, overweight and obesity has now dramatically risen in
low- and middle-income countries.Such countries are now facing a "double
burden" of disease, for while they continue to deal with the problems of
infectious disease and under-nutrition, they are also experiencing a rapid
upsurge in chronic disease risk factors such as obesity and overweight,
particularly in urban settings.
Under-nutrition and obesity often exist side-by-side within the same
country, the same community and even within the same household and this double
burden is caused by inadequate pre-natal, infant and young child nutrition
followed by exposure to high-fat, energy-dense, micronutrient-poor foods and
lack of physical activity.
Measuring Obesity
A crude population measure of obesity is the body mass index (BMI) which is
a simple index of weight-for-height that is commonly used in classifying
overweight and obesity in adult populations and individuals - a person's weight
in kilograms is divided by the square of the height in meters (kg/m2). BMI
provides the most useful population-level measure of overweight and obesity as
it is the same for both sexes and for all ages of adults but it is merely a
rough guide because it may not correspond to the same degree of fatness in
different individuals.
The WHO defines an adult who has a BMI between 25 and 29.9 as
overweight - an adult who has a BMI of 30 or higher is considered obese - a BMI
below 18.5 is considered underweight, and between 18.5 to 24.9 a healthy weight
.
BMI provides a benchmark for individual assessment, but experts
suspect that the risk of chronic disease in populations increases progressively
from a BMI of 21 upwards.
Measuring overweight and obesity in children aged 5 to 14 years
is challenging - the WHO Child Growth Standards includes BMI charts for infants
and young children up to age 5 - childhood obesity is associated with a higher
chance of premature death and disability in adulthood.
BMI ranges for children and teens are defined so that they take
into account normal differences in body fat between boys and girls and
differences in body fat at various ages. However although BMI correlates with
the amount of body fat, BMI does not directly measure body fat and some people,
such as athletes, may have a BMI that identifies them as overweight even though
they do not have excess body fat.
Other methods of estimating body fat and body fat distribution
include measurements of skinfold thickness and waist circumference, calculation
of waist-to-hip circumference ratios, and techniques such as ultrasound, computed tomography, and magnetic
resonance imaging (MRI).
Causes
of Obesity and Overweight
The basic cause of obesity and overweight is an energy imbalance between calories consumed
and calories expended and maintaining your current body weight indicates you
are in caloric balance and to gain or lose weight, will need the balance scale
to tip in one direction or another to achieve a goal.
Whether you want to lose weight or maintain a healthy weight,
the connection between the energy the body takes in, through the food and drink
consumed and the energy the body uses through the activities, must be taken
into consideration.
A number of factors play a role in obesity and it is a complex
health issue to address - behaviour, environment,culture, socioeconomic status
and genetic factors in disorders such as Bardet-Biedl
syndrome and Prader-Willi
syndrome - all play a part and may have an effect
in causing people to be overweight and obese.
Overweight and obesity are the result of an energy imbalance
where too many calories are eaten and not enough physical activity takes place.
Behaviour and environment play a large role causing people to be
overweight and obese and are the greatest areas for prevention and treatment
actions.
Maintaining a healthy weight for a lifetime involves balancing
the number of calories consumed with the number of calories the body uses or
"burns off."
A calorie is defined as a unit of energy supplied by food and is
a calorie regardless of its source - carbohydrates, fats, sugars, or proteins, all of them
contain calories. It takes approximately 3,500 calories below your calorie
needs to lose a pound of body fat - to lose 1 to 2 pounds a week, the caloric
intake must be reduced by 500-1000 calories per day.
There has been a global shift in diet towards increased intake
of energy-dense foods that are high in fat and sugars but low in vitamins, minerals and other micronutrients and this along
with a trend towards decreased physical activity has had a large impact on
worldwide increase in obesity rates. The increasingly sedentary nature of many
forms of work, changing modes of transportation, and increasing urbanization
have added to the problem.
Obesity,
What Can be Done?
Overweight and obesity, as well as their related chronic diseases, are largely preventable and at
an individual level, people can achieve energy balance and a healthy weight by
limiting energy intake from total fats and shifting fat consumption away from
saturated fats to unsaturated fats - increasing their consumption of fruit and
vegetables, as well as legumes, whole grains and nuts - limiting their intake
of sugars and increasing physical activity.
Experts recommend at least 30 minutes of regular, moderate-intensity
activity on most days - more activity may be required for weight control.
On a broader level governments and other stakeholders, by sustained
commitment, can play a vital role in shaping healthy environments and making
healthier diet options affordable and easily accessible. This is particularly
important for the most vulnerable in society - the poor and children, who have
limited choices about the food they eat and the environments in which they
live.
The Good News!
The key to success is to achieve an energy balance between calories consumed
and calories used up. Experts suspect that the risk of health problems starts
when someone is only very slightly overweight, and that the likelihood of
problems increases as someone becomes more and more overweight and many of
these conditions cause long-term suffering for individuals and families and are
costly for health systems.
Healthy diets and regular, adequate physical activity are major factors in
the promotion and maintenance of good health throughout the entire life course
and unhealthy diets and physical inactivity are two of the main risk factors
for raised blood pressure, raised blood glucose, abnormal blood lipids, overweight/obesity, and for the major chronic diseases such as cardiovascular diseases, cancer, and diabetes.
Overall, 2.7 million deaths are attributable to low fruit and vegetable
intake and 1.9 million deaths to physical inactivity - unhealthy diets and
physical inactivity are major risk factors for chronic diseases.
Unhealthy diets and physical inactivity are two of the main modifiable risk
factors for most of the main chronic diseases.
Physical Activity
Physical activity is defined as any bodily movement produced by skeletal muscles
that requires energy expenditure and physical inactivity is an independent risk
factor for chronic diseases, and overall is estimated to cause 1.9 million
deaths globally. Physical activity is fundamental to energy balance and weight
control - different types and amounts of physical activity are required for
different health outcomes - at least 30 minutes of regular, moderate-intensity
physical activity on most days is recommended by experts.
The Center for Disease Control and Prevention (CDC) says increasing
physical activity is a societal, not just an individual problem and demands a
population-based,multi-sectoral, multi-disciplinary, and culturally relevant
approach.
The intensity of different forms of physical activity varies between people
and the intensity of physical activity depends on an individuals previous
exercise experience and their relative level of fitness.
Metabolic Equivalents (METs) are commonly used to express the intensity of
physical activities. MET is the ratio of a person's working metabolic rate
relative to their resting metabolic rate. One MET is defined as the energy cost
of sitting quietly and is equivalent to a caloric consumption of 1kcal/kg/hour.
It is estimated that compared with sitting quietly, a person's caloric consumption
is three to six times higher when being moderately active (3-6 METs) and more
than six times higher when being vigorously active (>6 METs).
Benefits of
Physical Activity
Experts recommend that people throughout their lives engage in adequate
levels of physical activity for the benefit of their health - more physical
activity provides greater health benefits.
There is also evidence to suggest that increasing levels of various types
of physical activity may benefit health through positive effects on
hypertension, osteoporosis and falls risk, body weight and composition, musculoskeletal
conditions such as osteoarthritis and low back pain and mental and psychological health by reducing depression, anxiety and stress.
Physical activity also helps control risky behaviours particularly among
children and young people (e.g. tobacco use, alcohol / substance use, unhealthy
diet and violence). Regular physical activity may also benefit communities and
economies through increased productivity in the workplace, lower worker
absenteeism and turnover and better performing schools.
A significant proportion of many health budgets is spent on managing common
NCDs that are associated with inadequate physical activity and the promotion of
physical activity can be a highly cost-effective and sustainable public health
intervention.
Being physically active need not be expensive or involve equipment, special
shoes and clothes and can be done almost anywhere. Many everyday activities and
chores such as carrying groceries, wood, books or children are good
complementary physical activities, as is climbing the stairs instead of using
the elevator.
Walking is perhaps the most common and most highly recommended physical
activity, is absolutely free and can be done in urban areas, parks and even in
shopping centers. It is not essential to go to a gym, pool or other special
sports facility to be physically active.
Thirty minutes of moderate-intensity physical activity five days each week
will improve and maintain health and can be done in shorter blocks of 10
minutes each over the course of a day and incorporated into a daily routine -
at work, school, home or play.
Simple changes such as using stairs instead of lifts, riding a bike to work
or getting off the bus two stops before your final destination and then walking
the rest of the way can accumulate over the day and can form part of a regular
daily activity programme. Even the busiest people should be able to fit 30
minutes of physical activity into their daily routine to improve their health.
Physical Activity and Children
School-aged youth should accumulate at least 60 minutes of moderate- to
vigorous-intensity physical activity each day to ensure healthy development but
experts say less than one-third of young people are sufficiently active to
benefit their present and future health and well-being. This decline in
physical activity is largely due to increasingly common sedentary ways of life
- fewer children walk or cycle to school and excessive time is devoted to
watching television, playing computer games, and using computers - often at the
expense of time and opportunities for physical activity and sports - added to
this is the decrease in physical education and other school-based physical
activities.
Patterns of physical activity and healthy lifestyles acquired during
childhood and adolescence are more likely to be maintained throughout the
life-span and improving physical activity levels in young people is imperative
for the future health of all populations. Regular physical activity has been
shown to improve the functional status and quality of life of older adults and
also improves mental health and cognitive function .
Active lifestyles often provide older persons with regular occasions to
make new friendships, maintain social networks, and interact with other people
of all ages and to contribute to the management of disorders such as depression
Physical activity helps young people to develop healthy musculoskeletal tissues
(i.e. bones, muscles and joints), a healthy cardiovascular system (i.e. heart
and lungs), coordination and movement control, maintain a healthy body weight.
Physical activity has also been associated with psychological benefits in
young people by improving their control over anxiety and depression and
providing opportunities for self-expression, building self-confidence, social
interaction and integration.
While being active from an early age can help prevent many diseases,
regular movement and activity can also help relieve the disability and pain
associated with these conditions. Importantly, the benefits of physical
activity can be enjoyed even if regular practice starts late in life.
At least 60% of the world's population fails to meet the recommendations
for physical activity required to induce health benefits and NCDs associated
with physical inactivity are the greatest public health problem in most
countries around the world - levels of inactivity are high in virtually all
developed and developing countries.
Physical Activity and Women
Social inequality, poverty and inequitable access to resources, including
health care, result in a high burden of noncommunicable diseases (NCDs) among
women worldwide and though women generally tend to live longer with NCDs than
men, they are often in poor health.
Regular physical activity can improve women's health and help prevent many
of the diseases and conditions that are major causes of death and disability
for women around the world such as cardiovascular diseases which accounts for
one-third of deaths among women around the world and half of all deaths in
women over 50 years old in developing countries and diabetes which affects more
than 70 million women in the world and its prevalence is projected to double by
2025.
Osteoporosis is a disease in which bones become fragile and more likely to
break and is Physical Activity has also been associated with improved
psychological health by reducing levels of stress, anxiety and depression which
is particularly important for women who are twice as likely as men to develop
these conditions.
It has also been suggested that physical activity can contribute to
building self-esteem and confidence and can provide a vehicle for social
integration and equality for women in society.
Many factors hinder the participation of women in physical activity and
their access to health care - their income is often lower than that of men and
therefore the costs of access to physical activity facilities may be a barrier
- senior members of the household who control household resources may have to
agree before a woman can engage in physical activity - also women often have a
workload in the home and care-giving roles for other family members which may
limit the time available for them to engage in physical activity - women who
have limited mobility may be unable to travel to health centres.
Physical activity may also be restricted by cultural expectations and women
in rural and in low income urban areas women may also be already physically
exhausted by other forms of day-long "occupational" physical
activities.
Physical Activity and Seniors
Regular physical activity has been shown to improve the functional status
and quality of life of older adults and experts recommend that, if appropriate,
older adults should engage in at least 30 minutes of moderate-intensity
physical activity 5 days per week.
Many noncommunicable diseases (NCDs) prevalent in older adults can benefit
from participation in regular physical activity - while being active from an
early age can help prevent many diseases, regular movement and activity can
also help relieve the disability and pain associated with these conditions.
Importantly, the benefits of physical activity can be enjoyed even if regular
practice starts late in life. Older adults engaged in regular physical activity
have shown improved balance, strength, coordination and motor control flexibility
endurance - regular physical activity can reduce the risk of falls - a major
cause of disability among older people, and improve their mental health and
cognitive function.
It has also been found to contribute to the management of disorders such as
depression and anxiety - active lifestyles often provide older persons with
regular occasions to make new friendships, maintain social networks, and
interact with other people of all ages.
Physical activity for older adults can take many forms (e.g. walking, swimming,
stretching, dancing, gardening, hiking, cycling or organised exercise
sessions). However, there are several important considerations specific to the
older adult population with regard to physical activity recommendations:
aerobic activity should take into account the older adult's aerobic fitness -
activities that maintain or increase flexibility are recommended as are balance
exercises for those at risk of falls and medical conditions or disabilities
that may affect their capacity must be considered.
The number of people over 60 years old is projected to double in the next
20 years and most will be living in developing countries so reducing and
postponing age-related disability is an essential public health measure and
physical activity can play an important role in creating and sustaining
well-being at all ages.
Health gains worldwide would be achieved if the food industry seized the
initiative and reduced the fat, sugar and salt content of processed foods and
portion sizes and increased the introduction and marketing of innovative,
healthy, and nutritious choices.
The WHO Global Strategy on Diet, Physical Activity and Health called on all
stakeholders to take action at global, regional and local levels in order to
reduce the prevalence of chronic diseases and their common risk factors,
primarily unhealthy diet and physical inactivity.
WHO's work on diet and physical activity is part of the overall WHO chronic
disease prevention and control framework of the Department of Chronic Diseases
and Health Promotion. The strategic objectives of the department are to:
advocate for health promotion and chronic disease prevention and control;
promote health, especially for poor and disadvantaged populations; slow and
reverse the adverse trends in the common chronic disease risk factors; and
prevent premature deaths and avoidable disability due to major chronic
diseases.
This work is complemented by that of the Department of Nutrition for Health
and Development. The strategic objectives of the department are to promote
healthy diets and improve the nutritional status of the population throughout
the life course, particularly among the vulnerable. This is achieved by
providing support to countries in developing and implementing national
intersectoral Food and Nutrition Policies and Programmes to address
double-burden of nutrition-related ill-health, and to contribute to the
achievement of the Millennium Development Goals (MDGs).
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