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Obesity

Understanding Adult Obesity

Do You Know the Health Risks of Being Overweight?

Physical Activity and Weight Control


Understanding Adult Obesity

More than 60 percent of Americans aged 20 years and older are overweight. One-quarter of American adults are also obese, putting them at increased health risk for chronic diseases such as heart disease, type 2 diabetes, high blood pressure, stroke, and some forms of cancer.

This fact sheet provides basic information about obesity: What is it? How is it measured? What causes it? What are the health risks? What can you do about it?

What is obesity?

To 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 being obese.

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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.

Measuring 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 centers with special equipment.

There 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.

Because 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.

In recent years, body mass index (BMI) has become the medical standard used to measure overweight and obesity.

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Body Mass Index

BMI 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.

Although 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 obese.

Like 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.

Body Mass Index Graph

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.

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Body 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.

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Causes of Obesity

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.

Genetic factors

Obesity 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.

In 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.

Environmental factors

Genes do not destine people to a lifetime of obesity, however. Environment also strongly influences obesity. This includes lifestyle behaviors 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.

Although 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:

  • Learn how to choose more nutritious meals that are lower in fat.

  • Learn to recognize and control environmental cues (like inviting smells) that make you want to eat when you're not hungry.

  • Become more physically active.

  • Keep records of your food intake and physical activity.

Psychological factors

Psychological factors may also influence eating habits. Many people eat in response to negative emotions such as boredom, sadness, or anger.

Most 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.

During 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.

If you are upset by binge eating behavior and think you might have binge eating disorder, seek help from a health professional such as a psychiatrist, psychologist, or clinical social worker.

Other 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.

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Consequences of Obesity

Health Risks

Obesity 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.

Other diseases and health problems linked to obesity include:

  • Gallbladder disease and gallstones.

  • Liver disease.

  • Osteoarthritis, a disease in which the joints deteriorate. This is possibly the result of excess weight on the joints.

  • Gout, another disease affecting the joints.

  • Pulmonary (breathing) problems, including sleep apnea in which a person can stop breathing for a short time during sleep.

  • Reproductive problems in women, including menstrual irregularities and infertility.

Health care providers generally agree that the more obese a person is, the more likely he or she is to develop health problems.

Psychological and social effects

Emotional 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.

Many 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.

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Who should lose weight?

Health 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.

Preventing 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:

  • Family 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.

  • Pre-existing medical conditions. High blood pressure, high cholesterol levels, or high blood sugar levels are all warning signs of some obesity-associated diseases.

  • "Apple" shape. 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.

Fortunately, 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.

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How is obesity treated?

The 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, behavior modification, and sometimes weight-loss drugs. In cases of severe obesity, gastrointestinal surgery may be recommended. The most common type of obesity surgery is gastric bypass; the surgeons will create an egg-size pouch in the stomach and then attach it to a section of the patient’s intestine. The amount of food the patient can eat is reduced (due to the small size of the pouch) and less food is absorbed. Obesity surgery is not always safe nor should it be considered as a minor cosmetic surgery.

The Journal of the American Medical Association has reported that obesity surgery or stomach-reduction surgery leads to far more deaths than previously thought. Among the 35 to 44 year-olds more than 5 percent of men and nearly 3 percent of women died within a year after surgery and even more deaths were reported in patients 45 to 54 years old. Among patients 65 to 74, almost 13 percent of men and about 6 percent of women died and that is considered a high percentage. In patients 75 and older, half of the men and 40 percent of the women died. Surgery can be a deadly shock to the system especially in older patients. Aside from the general risk, the potentially deadly complications of obesity surgery include infection, malnutrition, bowel and gallbladder problems.

Remember, weight control is a life-long effort.

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Do You Know the Health Risks of Being Overweight?

Weighing too much may increase your risk for developing many health problems. If you are overweight or obese on a body mass index (BMI) chart (see page 2), you may be at risk for:

  • Type 2 diabetes
  • Heart disease and stroke
  • Cancer
  • Sleep apnea
  • Osteoarthritis
  • Gallbladder disease
  • Fatty liver disease.

You can lower your health risks by losing as little as 10 to 20 pounds.

Type 2 diabetes

What is it?

Type 2 diabetes used to be called adult-onset diabetes or noninsulin-dependent diabetes. It is the most common type of diabetes in the U.S. Type 2 diabetes is a disease in which blood sugar levels are above normal. High blood sugar is a major cause of early death, heart disease, kidney disease, stroke, and blindness.

How is it linked to overweight?

More than 80 percent of people with type 2 diabetes are overweight. It is not known exactly why people who are overweight are more likely to suffer from this disease. It may be that being overweight causes cells to change, making them less effective at using sugar from the blood. This then puts stress on the cells that produce insulin (a hormone that carries sugar from the blood to cells) and makes them gradually fail.

What can weight loss do?

You can lower your risk for developing type 2 diabetes by losing weight and increasing the amount of physical activity you do. If you have type 2 diabetes, losing weight and becoming more physically active can help you control your blood sugar levels. Losing weight and exercising more may also allow you to reduce the amount of diabetes medication you take.

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Heart disease and stroke

What is it?

Heart disease means that the heart and circulation (blood flow) are not functioning normally. If you have heart disease, you may suffer from a heart attack, congestive heart failure, sudden cardiac death, angina (chest pain), or abnormal heart rhythm. During a stroke, blood and oxygen do not flow normally to the brain, possibly causing paralysis or death. Heart disease is the leading cause of death in the U.S., and stroke is the third leading cause.

How is it linked to overweight?

People who are overweight are more likely to suffer from high blood pressure, high levels of triglycerides (blood fats) and LDL cholesterol (a fat-like substance often called the “bad cholesterol”), and low levels of HDL cholesterol (the “good cholesterol”). These are all risk factors for heart disease and stroke. In addition, people with more body fat have higher blood levels of substances that cause inflammation. Inflammation in blood vessels and throughout the body may raise heart disease risk.

What can weight loss do?

Losing 5 to 15 percent of your weight can lower your chances for developing heart disease or having a stroke. If you weigh 200 pounds, this means losing as little as 10 pounds. Weight loss may improve your blood pressure, triglyceride, and cholesterol levels; improve how your heart works and your blood flows; and decrease inflammation throughout your body.

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Cancer

What is it?

Cancer occurs when cells in one part of the body, such as the colon, grow abnormally or out of control and possibly spread to other parts of the body, such as the liver. Cancer is the second leading cause of death in the U.S.

How is it linked to overweight?

Being overweight may increase the risk of developing several types of cancer, including cancers of the colon, esophagus, and kidney. Overweight is also linked with uterine and postmenopausal breast cancer in women. Gaining weight during adult life increases the risk for several of these cancers. Being overweight also may increase the risk of dying from some cancers. It is not known exactly how being overweight increases cancer risk. It may be that fat cells make hormones that affect cell growth and lead to cancer. Also, eating or physical activity habits that may lead to being overweight may also contribute to cancer risk.

What can weight loss do?

Avoiding weight gain may prevent a rise in cancer risk. Weight loss, and healthy eating and physical activity habits, may lower cancer risk.

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Sleep apnea

What is it?

Sleep apnea is a condition in which a person stops breathing for short periods during the night. A person who has sleep apnea may suffer from daytime sleepiness, difficulty concentrating, and even heart failure.

How is it linked to overweight?

The risk for sleep apnea is higher for people who are overweight. A person who is overweight may have more fat stored around his or her neck. This may make the airway smaller. A smaller airway can make breathing difficult, loud (snoring), or stop altogether. In addition, fat stored in the neck and throughout the body can produce substances that cause inflammation. Inflammation in the neck may be a risk factor for sleep apnea.

What can weight loss do?

Weight loss usually improves sleep apnea. Weight loss may help to decrease neck size and lessen inflammation.

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Osteoarthritis

What is it?

Osteoarthritis is a common joint disorder. With osteoarthritis, the joint bone and cartilage (tissue that protects joints) wear away. Osteoarthritis most often affects the joints of the knees, hips, and lower back.

How is it linked to overweight?

Extra weight may place extra pressure on joints and cartilage, causing them to wear away. In addition, people with more body fat may have higher blood levels of substances that cause inflammation. Inflammation at the joints may raise the risk for osteoarthritis.

What can weight loss do?

Weight loss can decrease stress on your knees, hips, and lower back, and lessen inflammation in your body. If you have osteoarthritis, losing weight may help improve your symptoms.

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Gallbladder disease

What is it?

Gallstones are clusters of solid material that form in the gallbladder. They are made mostly of cholesterol and can sometimes cause abdominal or back pain.

How is it linked to overweight?

People who are overweight have a higher risk for developing gallbladder disease and gallstones. They may produce more cholesterol, a risk factor for gallstones. Also, people who are overweight may have an enlarged gallbladder, which may not work properly.

What can weight loss do?

Weight loss — especially fast weight loss (more than 3 pounds per week) or loss of a large amount of weight — can actually increase your chance of developing gallstones. Modest, slow weight loss of about 1/2 to 2 pounds a week is less likely to cause gallstones.

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Fatty liver disease

What is it?

Fatty liver disease occurs when fat builds up in the liver cells and causes injury and inflammation in the liver. It can sometimes lead to severe liver damage, cirrhosis (build-up of scar tissue that blocks proper blood flow in the liver), or even liver failure. Fatty liver disease is like alcoholic liver damage, but it is not caused by alcohol and can occur in people who drink little or no alcohol.

How is it linked to overweight?

People who have diabetes or “pre-diabetes” (when blood sugar levels are higher than normal but not yet in the diabetic range) are more likely to have fatty liver disease than people without these conditions. And people who are overweight are more likely to have diabetes. It is not known why some people who are overweight or diabetic get fatty liver and others do not.

What can weight loss do?

Losing weight can help you control your blood sugar levels. It can also reduce the build-up of fat in your liver and prevent further injury. People with fatty liver disease should avoid drinking alcohol.

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How can I lower my health risks?

If you are overweight, losing as little as 5 percent of your body weight may lower your risk for several diseases, including heart disease and diabetes. If you weigh 200 pounds, this means losing 10 pounds. Slow and steady weight loss of 1/2 to 2 pounds per week, and not more than 3 pounds per week, is the safest way to lose weight.

To lose weight and keep it off over time, try to make long-term changes in your eating and physical activity habits. Choose healthy foods, such as vegetables, fruits, whole grains, and low-fat meat and dairy products, more often and eat just enough food to satisfy you. Try to do at least 30 minutes of moderate-intensity physical activity—like walking—on most days of the week, preferably every day. To lose weight, or to maintain weight loss, you may need to do more than 30 minutes of moderate physical activity daily.

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Physical Activity and Weight Control

Physical activity helps you control your weight by using excess calories that would otherwise be stored as fat. Most foods you eat contain calories, and everything you do uses calories, including sleeping, breathing, and digesting food. Balancing the calories you eat with the calories you use through physical activity will help you reach and maintain a healthy weight.

Illustration of a balance scale

Calories in Food > Calories Used = Weight Gain
Calories in Food < Calories Used = Weight Loss
Calories in Food = Calories Used = Weight Control

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Becoming Physically Active

Experts recommend at least 30 minutes of moderate-intensity physical activity on most, if not all, days of the week. To achieve and maintain a healthy weight, particularly after you have lost a large amount of weight, you may need to do 60 minutes or more of moderate-intensity physical activity each day.

Physical activity may include structured activities such as walking, running, basketball, or other sports. It may also include daily activities such as household chores, yard work, or walking the dog. Pick a combination of structured and daily activities that fit your schedule.

If you have been inactive for a while, start slowly and work up to 30 minutes a day at a pace that is comfortable for you. If you are unable to be active for 30 minutes at one time, accumulate activity over the course of the day in 10- to 15-minute sessions.

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Health Benefits of Physical Activity

Regular physical activity helps control your weight and may help:

  • Reduce your risk of or manage chronic diseases such as type 2 diabetes, high blood pressure and cholesterol, heart disease, osteoporosis, arthritis, and some cancers;

  • Build strong muscles, bones, and joints;

  • Improve flexibility and balance;

  • Ward off depression; and

  • Improve mood and sense of well-being.

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Aerobic Activity

You can meet your goal of at least 30 minutes of moderate-intensity physical activity by participating in aerobic activities. Aerobic exercise includes any activity that makes you breathe harder than when you are resting and increases your heart rate.

Experts recommend moderate-intensity exercise. At this pace, you may breathe harder and find it more difficult to talk, but you should still be able to carry on a conversation. If you are just beginning, slowly work up to moving at a moderate-intensity pace.

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Get Started!

To add more physical activity to your daily life try:

  • Taking a brisk walk around the block with family, friends, or coworkers.

  • Raking the leaves.

  • Walking up the stairs instead of taking the elevator when it is safe to do so.

  • Mowing the lawn.

  • Taking an activity break at work or home. Get up and stretch or walk around.

  • Parking your car further away from entrances of stores, movie theatres, or your home and walk the extra distance when it is safe to do so.

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Strength Training

Strength training is another way for you to meet the recommended minimum of 30 minutes of moderate-intensity physical activity each day. Strength training will also help you burn extra calories and build strong muscles, bones, and joints.

Experts recommend strength training 2 to 3 days each week, with 1 full day of rest between workouts to allow your muscles to recover. If you are new to strength training, or physical activity in general, consider hiring a certified personal trainer who can plan an individualized program to help you work out safely and effectively. A personal trainer who has a degree in exercise physiology or is certified through a national certification program such as the American College of Sports Medicine or National Strength and Conditioning Association may be able to help you reach your physical activity goals.

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Get Strong!

Build strong muscles and bones with strengthening exercise. Try:

  • Lifting weights
  • Using resistance bands
  • Using stability or medicine balls
  • Doing push-ups and abdominal crunches

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Mind and Body Exercise

In addition to aerobic activity and strength training, you may wish to include other forms of exercise in your physical activity program. Alternatives to traditional exercise provide variety and fun. They may also help reduce stress, increase muscular strength and flexibility, and increase energy levels. Examples of these exercises include yoga, Pilates, and tai chi.

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Keep Moving!

Move at your own pace while you enjoy some of these activities:

  • Brisk walking
  • Jogging
  • Bicycling
  • Swimming
  • Aerobic exercise classes (step aerobics, kick boxing, high/low)
  • Dancing (square dancing, salsa, African dance, swing)
  • Playing sports (basketball, soccer)

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Tips to a Safe and Successful Physical Activity Program

  • Check with your health care provider. If you have a chronic health problem such as obesity, diabetes, heart disease, or high blood pressure, ask your health care provider about what type and amount of physical activity is right for you.

  • Start slowly. Incorporate more physical activity into your daily routine and gradually work up to the 30-minute goal to improve health and manage your weight.

  • Set goals. Set short-term and long-term goals and celebrate every success.

  • Track progress. Keep an activity log to track your progress. Note when you worked out, what activity you did, how long you did the activity, and how you felt during your workout.

  • Think variety. Choose a variety of physical activities to help you meet your goals, prevent boredom, and keep your mind and body challenged.

  • Be comfortable. Wear comfortable shoes and clothes, and ones that are appropriate to the activity you will be doing.

  • Listen to your body. Stop exercising and consult your health care provider if you experience chest discomfort or pain, dizziness, severe headache, or other unusual symptoms while you work out. If pain does not go away, get medical help right away. If you are feeling fatigued or sick, take time off from your routine to rest. You can ease back into your program when you start feeling better.

  • Eat nutritious foods. Choose a variety of nutritious foods every day. Remember that your health and weight depend on both your eating plan and physical activity level.

  • Get support. Encourage your family and friends to support you and join you in your activity. Form walking groups with coworkers, play with your children outside, or take a dance class with friends.

Regular physical activity will help you feel, move, and look better. Whether your goal is to achieve and maintain a healthy weight or improve your health, becoming physically active is a step in the right direction. Take advantage of the health benefits of physical activity and make it a part of your life.

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Obesity