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. Obesity means having a high amount
of extra body fat. Being overweight or obese raises your risk for health problems.
Coronary heart disease
Type 2 diabetes
High blood pressure
Some types of cancer.
Public health experts agree that overweight and obesity have reached epidemic proportions
in this country and around the world. More than one-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 20% of U.S. children and teens
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 often 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. Sometimes 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 ideal. A BMI between 25
and 29.9 is considered overweight. A person is considered obese if the BMI is 30 or
In general, after the age of 50, the weight of a person assigned male at birth weight
tends to stay the same and often decreases slightly between ages 60 and 74. In contrast,
the weight of a person assigned female at birth 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 linked to type 2 diabetes, high cholesterol, high blood pressure, and
heart disease. A waist circumference of more than 40 inches in people assigned male
at birth and more than 35 inches in people assigned female at birth 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 they use for energy each day will gain weight.
But the risk factors that determine obesity can be complex. They are often 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 the following.
Studies show that the likelihood of becoming obese is passed down through a family's
genes. Researchers have found several genes that seem 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 1 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.
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 set off hunger. Another hormone called
leptin can decrease appetite. Another example is polycystic ovary syndrome (PCOS),
a condition caused by high levels of certain hormones. A person with PCOS is more
likely to be obese.
How much money you make may affect whether you are obese. This is especially true
for people assigned female at birth. Those who are poor and of lower social status
are more likely to be obese than those of higher socioeconomic status. This is especially
true among minority groups.
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 like corticosteroids, beta-blockers, some antidepressants, and antiseizure
medicines can cause you to gain some extra weight.
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 $150 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
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
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. That's 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. It causes sleepiness during the day. It also causes heavy
snoring. Sleep apnea is also linked to high blood pressure, increased risk for heart
disease, stroke, diabetes, and can even cause an early death. Breathing problems tied
to obesity happen when added weight of the chest wall squeezes the lungs. This restricts
Being overweight or obese increases your risk for a variety of cancers, according
to the American Cancer Society. Among obese people assigned female at birth, the risk
increases for cancer of the endometrium or the lining of the uterus. Obese people
assigned female at birth also increase their risk for breast cancers in those who
have gone through menopause. People assigned male at birth who are overweight have
a higher risk for prostate cancer. People who are obese are at increased risk for
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
3 of these risk factors confirms the diagnosis of metabolic syndrome.
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's 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 those who are overweight may lead to discrimination
and even bullying. Depression and anxiety are more common in people who are overweight