most people, the term "obesity" means to be very overweight. Health
professionals define "overweight" as an excess amount of body
weight that includes muscle, bone, fat, and water. "Obesity" specifically
refers to an excess amount of body fat. Some people, such as bodybuilders
or other athletes with a lot of muscle, can be overweight without
How is obesity measured?
Everyone needs a
certain amount of body fat for stored energy, heat insulation,
shock absorption, and other functions. As a rule, women have more
body fat than men. Most health care providers agree that men with
more than 25 percent body fat and women with more than 30 percent
body fat are obese.
the exact amount of a person's body fat is not easy. The most accurate
measures are to weigh a person underwater or to use an X-ray test
called Dual Energy X-Ray Absorptiometry (DEXA). These methods are
not practical for the average person, and are done only in research
centres with special equipment.
are simpler methods to estimate body fat. One is to measure the thickness
of the layer of fat just under the skin in several parts of the body.
Another involves sending a harmless amount of electricity through a
person's body. Both methods are used at health clubs and commercial
weight loss programs. Results from these methods, however, can be inaccurate
if done by an inexperienced person or on someone with severe obesity.
measuring a person's body fat is difficult, health care providers
often rely on other means to diagnose obesity. Weight-for-height tables,
which have been used for decades, usually have a range of acceptable
weights for a person of a given height. One problem with these tables
is that there are many versions, all with different weight ranges. Another
problem is that they do not distinguish between excess fat and muscle.
A very muscular person may appear obese, according to the tables, when
he or she is not.
recent years, body mass index (BMI) has become the medical standard
used to measure overweight and obesity.
uses a mathematical formula based on a person's height and weight.
BMI equals weight in kilograms divided by height in meters squared (BMI
= kg/m2). The BMI table that follows has already calculated this information.
the BMI ranges shown in the table are not exact ranges of healthy and
unhealthy weight, they are useful guidelines. A BMI of 25 to 29.9 indicates
a person is overweight. A person with a BMI of 30 or higher is considered
the weight-to-height table, BMI does not show the difference between excess
fat and muscle. BMI, however, is closely associated with measures of body
fat. It also predicts the development of health problems related to excess
weight. For these reasons, BMI is widely used by health care providers.
Find your weight on the bottom of the graph. Go straight
up from that point until you come to the line that matches your height.
Then look to find your weight group.
Fat Distribution: "Pears" vs. "Apples"
Health care providers are concerned not only with how much fat a person
has, but also where the fat is located on the body. Women typically
collect fat in their hips and buttocks, giving them a "pear"
shape. Men usually build up fat around their bellies, giving them more
of an "apple" shape. Of course some men are pear-shaped and
some women become apple-shaped, especially after menopause. If you carry
fat mainly around your waist, you are more likely to develop obesity-related
health problems. Women with a waist measurement of more than 35 inches
or men with a waist measurement of more than 40 inches have a higher
health risk because of their fat distribution.
In scientific terms, obesity occurs when a person consumes
more calories than he or she burns. What causes this imbalance between
calories in and calories out may differ from one person to another. Genetic,
environmental, psychological, and other factors may all play a part.
tends to run in families, suggesting a genetic cause. Yet families also
share diet and lifestyle habits that may contribute to obesity. Separating
these from genetic factors is often difficult. Even so, science shows
that heredity is linked to obesity.
one study, adults who were adopted as children were found to have weights
closer to their biological parents than to their adoptive parents. In
this case, the person's genetic makeup had more influence on the
development of obesity than the environment in the adoptive family home.
do not destine people to a lifetime of obesity, however. Environment also
strongly influences obesity. This includes lifestyle behaviours such as
what a person eats and his or her level of physical activity. Americans
tend to eat high-fat foods, and put taste and convenience ahead of nutrition.
Also, most Americans do not get enough physical activity.
you cannot change your genetic makeup, you can change your eating habits
and levels of activity. Try these techniques that have helped some people
lose weight and keep it off:
how to choose more nutritious meals that are lower in fat.
to recognize and control environmental cues (like inviting smells) that
make you want to eat when you're not hungry.
more physically active.
records of your food intake and physical activity.
factors may also influence eating habits. Many people eat in response
to negative emotions such as boredom, sadness, or anger.
overweight people have no more psychological problems than people of average
weight. Still, up to 10 percent of people who are mildly obese and try
to lose weight on their own or through commercial weight loss programs
have binge eating disorder. This disorder is even more common in people
who are severely obese.
a binge eating episode, people eat large amounts of food and feel that
they cannot control how much they are eating. Those with the most severe
binge eating problems are also likely to have symptoms of depression and
low self-esteem. These people may have more difficulty losing weight and
keeping it off than people without binge eating problems.
you are upset by binge eating behaviour and think you might have binge
eating disorder, seek help from a health professional such as a psychiatrist,
psychologist, or clinical social worker.
causes of obesity
Some illnesses can lead to obesity or a tendency to gain weight. These
include hypothyroidism, Cushing's syndrome, depression, and certain
neurological problems that can lead to overeating. Also, drugs such as
steroids and some antidepressants may cause weight gain. A doctor can
tell whether there are underlying medical conditions that are causing
weight gain or making weight loss difficult.
is more than a cosmetic problem; it is a health hazard. Approximately
280,000 adult deaths in the United States each year are related to obesity.
Several serious medical conditions have been linked to obesity, including
type 2 diabetes, heart disease, high blood pressure, and stroke. Obesity
is also linked to higher rates of certain types of cancer. Obese men are
more likely than non-obese men to die from cancer of the colon, rectum,
or prostate. Obese women are more likely than non-obese women to die from
cancer of the gallbladder, breast, uterus, cervix, or ovaries.
diseases and health problems linked to obesity include:
disease and gallstones.
a disease in which the joints deteriorate. This is possibly the result
of excess weight on the joints.
another disease affecting the joints.
(breathing) problems, including sleep apnea in which a person can
stop breathing for a short time during sleep.
problems in women, including menstrual irregularities and infertility.
care providers generally agree that the more obese a person is, the more
likely he or she is to develop health problems.
and social effects
suffering may be one of the most painful parts of obesity. American society
emphasizes physical appearance and often equates attractiveness with slimness,
especially for women. Such messages make overweight people feel unattractive.
people think that obese individuals are gluttonous, lazy, or both, even
though this is not true. As a result, obese people often face prejudice
or discrimination in the job market, at school, and in social situations.
Feelings of rejection, shame, or depression are common.
should lose weight?
care providers generally agree that people who have a BMI of 30 or more
can improve their health through weight loss. This is especially true
for people who are severely obese.
additional weight gain is recommended if you have a BMI between 25 and
29.9, unless you have other risk factors. Obesity experts recommend you
try to lose weight if you have two or more of the following:
history of certain chronic diseases. If
you have close relatives who have had heart disease or diabetes, you
are more likely to develop these problems if you are obese.
High blood pressure, high cholesterol levels, or high blood sugar
levels are all warning signs of some obesity-associated diseases.
If your weight is concentrated around your waist, you may have a higher
risk of heart disease, diabetes, or cancer than people of the same
weight who have a "pear" shape.
a weight loss of 5 to 10 percent can do much to improve health by lowering
blood pressure and cholesterol levels. In addition, recent research has
shown that a 5- to 7-percent weight loss can prevent type 2 diabetes in
people at high risk for the disease.
How is obesity treated?
method of treatment depends on your level of obesity, overall health condition,
and motivation to lose weight. Treatment may include a combination of
diet, exercise, behaviour modification, and sometimes weight-loss drugs.
In some cases of severe obesity, gastrointestinal surgery may be recommended.
Remember, weight control is a life-long effort.