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Obesity is an excess proportion of total body fat.
A person is considered obese when his or her weight is 20% or more
above normal weight. The most common measure of obesity is the body
mass index or BMI. A person is considered obese if his or her BMI
is over 30.
"Morbid obesity" means that a person
is either 50%-100% over normal weight, more than 100 pounds over
normal weight, or sufficiently overweight to severely interfere
with health or normal function.
What Causes Obesity?
Obesity occurs when a person consumes more calories
than he or she burns. What causes this imbalance between consuming
and burning calories is unclear. Evidence suggests that obesity
often has more than one cause. They may include.
Age. As you get older, your body's
ability to metabolize food slows down and you do not require as
many calories to maintain your weight. This is why people note that
they eat the same and do the same activities as they did when they
were 20 years old, but at age 40, gain weight.
Gender. Women tend to be more
overweight than men. Men have a higher resting metabolic rate (meaning
they burn more energy at rest) than females, so males require more
calories to maintain their body weight. Additionally, when women
become post-menopausal, their metabolic rate decreases significantly.
That is partly why many women gain weight after menopause.
Genetics. Obesity (and thinness)
tends to run in families. In a study of adults who were adopted
as children, researchers found that participating adult weights
were closer to their biological parents' weights than their adoptive
parents'. The environment provided by the adoptive family apparently
had less influence on the development of obesity than the person's
genetic makeup. In fact, if your biological mother is heavy as an
adult, there is approximately a 75% chance that you will be heavy.
If your biological mother is thin, there is also a 75% chance that
you will be thin. Nevertheless, people who feel that their genes
have doomed them to a lifetime of obesity should take heart. Many
people genetically predisposed to obesity do not become obese or
are able to lose weight and keep it off.
Environmental factors. Although
genes are an important factor in many cases of obesity, a person's
environment also plays a significant role. Environmental factors
include lifestyle behaviors such as what a person eats and how active
he or she is.
Physical activity. Active individuals
require more calories than less active ones to maintain their weight.
Additionally, physical activity tends to decrease appetite in obese
individuals while increasing the body's ability to preferentially
metabolize fat as an energy source. Much of the increase in obesity
in the last 20 years is thought to have resulted from the decreased
level of daily physical activity.
Psychological factors. Psychological
factors also influence eating habits. Many people eat in response
to negative emotions such as boredom, sadness, or anger. While most
overweight people have no more psychological disturbances than people
at their normal weight, about 30% of people who seek treatment for
serious weight problems have difficulties with binge eating. During
a binge-eating episode, people eat large amounts of food while feeling
they can't control how much they are eating.
Illness. Some rare illnesses can
cause obesity. These include hormone problems such as hypothyroidism
(poorly acting thyroid slows metabolism), depression and some rare
diseases of the brain that can lead to overeating.
Medication. Certain drugs, such
as steroids and some antidepressants, may cause excessive weight
gain.
Emotional Aspects of Obesity
One of the most painful aspects of obesity may
be the emotional suffering it causes. American society places great
emphasis on physical appearance, often equating attractiveness with
slimness or muscularity. In addition, many people wrongly stereotype
obese people as gluttonous, lazy, or both. However, more and more
evidence contradicts this assumption. Obese people often face prejudice
or discrimination at work, at school, while looking for a job, and
in social situations. Feelings of rejection, shame, or depression
are common.
When to Seek Help
You should call your doctor if you are having emotional
problems related to your weight, need help losing weight, or if
you fall into either of these categories.
If your BMI is 30 or greater, you're considered
obese. You should talk to your doctor about losing weight since
you are at high risk of having health problems.
If you have an "apple shape" - a so-called, "potbelly"
or "spare tire" -- you carry more fat in and around your
abdominal organs. Fat in your abdomen increases your risk of many
of the serious conditions associated with obesity. Women's waist
measurement should fall below 35 inches. Men's should be less than
40 inches. If you have a large waist circumference, talk to your
doctor about how you can lose weight.
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