Overview of Obesity
Facts about obesity
Overweight and obesity together make up one of the leading preventable causes of death
in the U.S. Obesity is a chronic disease that can seriously affect your health.
Overweight means that you have extra body weight, and obesity means having a high
amount of extra body fat. Being overweight or obese raises your risk for health problems.
These include coronary heart disease, type 2 diabetes, asthma, high cholesterol, high
blood pressure, sleep apnea, and certain types of cancer.
Public health experts agree that overweight and obesity have reached epidemic proportions
in this country and around the world. More than a third of U.S. adults are obese.
People ages 60 and older are more likely to be obese than younger adults, according
to the most recent data from the National Health and Nutrition Examination Survey.
And the problem also affects children. Approximately 17%, of U.S. children and adolescents
ages 2 to 19 are obese.
Overweight and obesity are different points on a scale that ranges from being underweight
to being morbidly obese. Where you fit on this scale is determined by your body mass
BMI is a measure of your weight as it relates to your height. BMI usually gives you
a good idea of the amount of body fat you have. Your healthcare providers use BMI to
find out your risk for obesity-related diseases. Occasionally, some very muscular
people may have a BMI in the overweight range. But these people are not considered
overweight because muscle tissue weighs more than fat tissue.
In general, a BMI from 20 to 24.9 in adults is considered to be ideal. A BMI of more
than 25 is considered overweight. A person is considered obese if the BMI is greater
than 30 and is considered to have morbid obesity if the BMI is 40 or greater. In general,
after the age of 50, a man's weight tends to stay the same and often decreases slightly
between ages 60 and 74. In contrast, a woman's weight tends to increase until age
60, and then begins to decrease.
Obesity can also be measured by waist-to-hip ratio. This is a measurement tool that
looks at the amount of fat on your waist, compared with the amount of fat on your
hips and buttocks. The waist circumference tells the amount of stomach fat. Increased
stomach fat is associated with type 2 diabetes, high cholesterol, high blood pressure,
and heart disease. A waist circumference of more than 40 inches in men and more than
35 inches in women may increase the risk for heart disease and other diseases tied
to being overweight.
Talk with your healthcare provider if you have questions about healthy body weight.
What causes obesity?
In many ways, obesity is a puzzling disease. Experts don't know exactly how your body
regulates your weight and body fat. What they do know is that a person who eats more
calories than he or she uses for energy each day will gain weight.
But the risk factors that determine obesity can be complex. They are usually a combination
of your genes, socioeconomic factors, metabolism, and lifestyle choices. Some endocrine
disorders, diseases, and medicines may also affect a person's weight.
Factors that may affect obesity include:
Genetics. Studies show that the likelihood of becoming obese is passed down through a family's
genes. Researchers have found several genes that appear to be linked with obesity.
Genes, for instance, may affect where you store extra fat in your body. But most researchers
think that it takes more than just one gene to cause an obesity epidemic. They are
continuing to do more research to better understand how genes and lifestyle interact
to cause obesity. Because families eat meals together and share other activities,
environment and lifestyle also play a role.
Metabolism factors. How your body uses energy is different from how another person's uses it. Metabolism
and hormones differ from person to person, and these factors play a role in how much
weight you gain. One example is ghrelin, the "hunger
hormone" that regulates appetite. Researchers have found that ghrelin may help trigger
hunger and give you a feeling of fullness. Another example is polycystic ovary syndrome
(PCOS), a condition in women caused by high levels of certain hormones. A woman with
PCOS is more likely to be obese.
Socioeconomic factors. How much money you make may affect whether you are obese. This is especially true
for women. Women who are poor and of lower social status are more likely to be obese
than women of higher socioeconomic status. This is especially true among minority
Lifestyle choices. Overeating and a lack of exercise both contribute to obesity. But you can change these
lifestyle choices. If many of your calories come from refined foods or foods high
in sugar or fat, you will likely gain weight. If you don't get much if any exercise,
you'll find it hard to lose weight or maintain a healthy weight.
Medicines. Medicines like corticosteroids, antidepressants, and antiseizure medicines can cause
you to gain some extra weight.
Emotions. Emotional eating–eating when you're bored or upset–can lead to weight gain. Too little
sleep may also contribute to weight gain. People who sleep fewer than 5 hours a night
are more likely to become obese than people who get 7 to 8 hours of sleep a night.
Health effects of obesity
Obesity has a far-ranging negative effect on health. Each year in the U.S., obesity-related
conditions cost more than $100 billion and cause premature deaths. The health effects
linked with obesity include:
High blood pressure. Excess weight needs more blood to circulate to the fat tissue and causes the blood
vessels to become narrow (coronary artery disease). This makes the heart work harder,
because it must pump more blood against more resistance from the blood vessels and
can lead to a heart attack (myocardial infarction). More circulating blood and more
resistance also means more pressure on the artery walls. Higher pressure on the artery
walls increases the blood pressure. Excess weight also raises blood cholesterol and
triglyceride levels and lowers HDL ("good") cholesterol levels, adding to the risk
of heart disease.
Type 2 diabetes. Obesity is the major cause of type 2 diabetes. Obesity can make your body resistant
to insulin, the hormone that regulates blood sugar. When obesity causes insulin resistance,
your blood sugar level rises. Even moderate obesity dramatically increases the risk
Heart disease. Atherosclerosis, or hardening of the arteries, happens more often in obese people.
Coronary artery disease is also more common in obese people because fatty deposits
build up in arteries that supply the heart. Narrowed arteries and reduced blood flow
to the heart can cause chest pain called angina or a heart attack. Blood clots can
also form in narrowed arteries and travel to the brain, causing a stroke.
Joint problems, including osteoarthritis. Obesity can affect the knees and hips because extra weight stresses the joints. Joint
replacement surgery may not be a good choice for an obese person because the artificial
joint has a higher risk of loosening and causing more damage.
Sleep apnea and respiratory problems are also related to obesity. Sleep apnea causes people to stop breathing for brief periods during sleep. Sleep
apnea interrupts sleep and causes sleepiness during the day. It also causes heavy
snoring. Sleep apnea is also linked to high blood pressure. Breathing problems tied
to obesity happen when added weight of the chest wall squeezes the lungs. This restricts
Cancer. Being overweight or obese increases your risk for a variety of cancers, according
to the American Cancer Society. Among obese women, the risk increases for cancer of
the endometrium or the lining of the uterus in younger women. Obese women also increase
their risk for breast cancers in those who have gone through menopause. Men who are
overweight have a higher risk for prostate cancer. Both men and women who are obese
are at increased risk for colorectal cancer.
Metabolic syndrome. The National Cholesterol Education Program says that metabolic syndrome is a risk
factor for cardiovascular disease. Metabolic syndrome has several major risk factors.
These are stomach obesity, high blood triglyceride levels, low HDL cholesterol levels,
high blood pressure, and insulin resistance (severe type 2 diabetes). Having at least
three of these risk factors confirms the diagnosis of metabolic syndrome.
Psychosocial effects. People who are overweight or obese can have problems socially or psychologically.
This is because the culture in the U.S. often values a body image that's overly thin.
Overweight and obese people are often blamed for their condition. Other people may
think of them as lazy or weak-willed. It is not uncommon for people who are overweight
or obese to earn less than other people or to have fewer or no romantic relationships.
Some people's disapproval and bias against of those who are overweight may progress
to discrimination, and even torment. Depression is more common in people who are overweight