Obesity 2295
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Obesity (o-BEE-si-tee) is an excess of body fat.


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Bariatric medicine


Karen's Story

Karen was a large baby who grew into a very large child. By the time she was 12 years old, Karen was 60 pounds overweight. She was also an after-school couch potato, who spent much of her free time munching chips and cookies in front of the television or chatting with on-line friends at the computer. The more weight Karen gained, the tougher it was to catch her breath when she did try to exercise, and the harder it became to deal with the face-to-face teasing of classmates. Finally, one day Karen decided that a change was in order. Since both of her parents were overweight too, it became a family project. Karen and her parents began going to the local YMCA to exercise almost every day. They also learned how to eat a leaner, healthier diet. Before long, Karen was slimmer, trimmer, and able to enjoy a more active life with her friends.

What Is Obesity?

Obesity is the medical term for an increase in body weight, beyond what doctors usually recommend, as the result of an excess of body fat. It is slightly different from overweight, which is the term for an excess of body weight caused by bone, muscle, and other body tissues and fluids in addition to body fat. In other words, it is possible to be overweight without being obese. For example, body builders might weigh more than normal because they have a large amount of muscle mass. Yet they usually would not have obesity, because the amount of fat on their bodies is not above normal.

Body fat (adipose tissue) is made up of fat cells. Obesity results when the body has too many fat cells or when fat cells are overfilled with fat. © C.P. Hickman/Visuals Unlimited.
Body fat (adipose tissue) is made up of fat cells. Obesity results when the body has too many fat cells or when fat cells are overfilled with fat.
© C.P. Hickman/Visuals Unlimited.

It is also possible to be obese without being overweight. For example, a very inactive person with little muscle mass might be of normal weight but still have too much body fat. However, most people with obesity are also overweight.

As a rule, women have more fat on their bodies than men. Women with more than 30 percent body fat and men with more than 25 percent body fat are usually considered to have obesity. The rules are less clearcut for children, as many go through growth spurts in which they may put on weight first, then catch up in height later. A doctor is the best person to judge whether a child weighs more than medical professionals usually recommend.

What Are the Health Risks?

Children have fewer health problems from being heavy than adults do. However, such children may suffer stress because they look different from their friends. Some, especially those who are genetically * prone to such conditions, may also have higher blood pressure and higher blood cholesterol * . The greatest health risk faced by overweight children, though, is that they are more likely to be obese when they become adults.

For adults, obesity is much more than a matter of looks. It is a serious health hazard. The more obese a person is, the more likely that person is to develop health problems. A person who has weighed 40 percent more than doctors recommend for at least 10 years is twice as likely to die early as someone who weighs no more than doctors recommend. Adults with obesity face several health risks:

Heart disease and stroke

The leading causes of death and disability in the United States are heart disease and stroke. Stroke is a disorder that occurs when a blood vessel to the brain is blocked or bursts. People who are obese are more likely to have high blood pressure, which raises the risk of heart disease and stroke. Obesity is also linked to having higher levels of cholesterol and fats in the blood, which can lead to heart disease. In addition, obesity is linked to sudden death from heart disease and to stroke and chest pain caused by decreased oxygen reaching the heart muscle.


Type 2 diabetes (dy-a-BEE-teez) is the most common form of diabetes, a disorder that reduces the body's ability to control blood sugar. It is a major cause of early death, heart disease, kidney disease, stroke, and blindness. People with obesity are twice as likely as other people to get type 2 diabetes.


Men who are obese are more likely than other men to get cancer of the colon (main part of the large intestine), rectum (lower part of the large intestine), and prostate (PROS-tate; male gland in front of the rectum). Women with obesity are more likely than other women to get cancer of the colon, uterus (womb), cervix (lower part of the uterus), ovaries (female glands where egg cells develop), gallbladder (small sac under the liver), and breast. For some types of cancer, such as colon and breast, it is not clear whether the greater risk is due to extra body fat or to a high-fat and high-calorie diet.

Gallbiadder disease

People with obesity are more likely than other people to get gallbladder disease and gallstones, rock-like lumps that form in the gallbladder. Ironically, rapid weight loss itself can also lead to gallstones. Slower weight loss of about one pound a week is less likely to cause this problem.

* genetically ae-NE-ti-klee) means due to heredity, and stemming from genes, the material in the body that helps determine physical and mental characteristics, such as hair or eye color.

* cholesterol (ko-LES-ter-ol) is a fat-like substance found in the blood-stream, Too much cholesterol in the blood has been linked to heart disease.


Osteoarthritis (os-te-o-ar-THRY-tis) is a common disease that affects the joints (places where bones meet), especially those in the knees, hips, and lower back. Extra weight seems to promote osteoarthritis by putting extra pressure on these joints and wearing away the tissue that cushions and protects them.


Gout (GOWT) is a joint disease that can lead to problems with the kidneys (organs that filter blood and get rid of waste products and excess water as urine). Gout is more common in people with obesity. Some diets may cause an attack of gout in people who are prone to it. Such people should check with a doctor before dieting.

Sleep apnea

Sleep apnea (AP-nee-a) is a serious breathing disorder, which can cause a person to stop breathing for short periods during sleep and to snore heavily. It can lead to daytime sleepiness and sometimes heart failure. The more severe the obesity a person has, the greater the risk of getting sleep apnea.

What Causes Obesity?

People with obesity often are the subject of cruel jokes. It is important to remember, however, that obesity is a medical condition, not a character flaw. In the simplest terms, obesity occurs when people take in more calories * than they burn. The reason for this imbalance is still unclear. However, research studies suggest that there may be multiple causes.


Children whose parents, brothers, or sisters have obesity are also more likely to develop obesity. Obesity does tend to run in families. However, not all children with a family history of obesity develop it themselves. Genes * may be one cause for those who do. Shared family behaviors, such as poor eating and exercise habits, also may play a part.


People's diet and activity level are both important factors affecting their weight. Americans tend to eat high-fat diets and lead inactive lifestyles. This is true of young people as well. More than four out of five young people eat too much fat, and almost half of those between ages 12 and 21 do not get regular vigorous exercise. One reason children are less active today is because of televisions, computers, and video games. The average American child spends many hours a week watching television, time that could be spent being active.


Many people eat when they feel bored, sad, or angry. In general, though, most people with obesity are as mentally healthy as anyone else. However, about 30 percent of people who are treated for severe obesity have trouble with binge (BINJ) eating. This means that they eat large amounts of food while feeling that they cannot control how much they are eating. Those with the most severe eating problems are said to have binge eating disorder. People with this disorder have more trouble than usual taking weight off and keeping it off.

Just the Facts

  • The percentage of young people in the United States who are overweight has more than doubled in the past 30 years.
  • About 58 million American adults have obesity.
  • At any time in the United States, at least a third of women and a fifth of men are trying to lose weight.
  • Poor diet and an inactive lifestyle cause at least 300,000 deaths among American adults each year.

* calories (KAL-o-reez) are units of energy that are used to measure both the amount of energy in food and the amount of energy the body uses.

* genes are chemicals in the body that help determine a person's characteristics, such as hair or eye color. They are inherited from a person's parents and are contained in the cells of the body.

Scientists use lab mice, like the one shown on the left, for research on the genetic causes of obesity. © Jackson/Visuals Unlimited.
Scientists use lab mice, like the one shown on the left, for research on the genetic causes of obesity.
© Jackson/Visuals Unlimited.


In rare cases, obesity is caused by a medical illness, such as a problem with hormones. These are chemicals that are needed for the body to work normally. Certain drugs also may cause weight gain.

How Is Body Fat Measured?

Measuring a person's body fat is not as easy as it sounds. The most accurate method is to weigh the person underwater. However, this can only be done at laboratories with special equipment. There are two simpler ways for estimating body fat, although they can give faulty results if done by an unskilled person or on someone who has severe obesity. The first involves measuring the thickness of skin folds on various parts of the body. The second involves sending a harmless amount of electric current through the person's body. Both are widely used, but are often inaccurate. Doctors often rely on other ways to diagnose obesity:

Growth charts

For children, doctors may use a chart that shows whether a child's weight at a certain height and age is within a healthy range. The doctor also takes the child's growth pattern into account.

Fad Diets

Fad diets are diets that usually have the goal of helping people lose a lot of weight in a short time. They become fads when they are widely advertised and reported in magazines, newspapers, television, and radio.

Fad diets often revolve around eating a particular food or food group. Fad diets have included the Cabbage Soup Diet, the Grapefruit Diet, the High Fat, High Protein, Low Carbohydrate Diet, and the Fat Burning Diet.

Realistic expectations for a weight-loss diet are the loss of about one half pound (250 grams) of fat over one week. Any more weight lost than that probably will be water.

The best diets recommend exercising and eating a balance of foods from all food groups. It is important to talk with a doctor before trying any diet.

Weight-for-height tables

For adults, doctors may use a table that shows a range of healthy weights for a person of a given height. Some tables also take the person's sex, age, and frame size into account.

Doctors use charts showing height, weight, and body mass index as guide-lines for determining whether people are at a healthy weight or whether they are overweight.
Doctors use charts showing height, weight, and body mass index as guide-lines for determining whether people are at a healthy weight or whether they are overweight.

Body mass index = [weight in kilograms] ÷ [height in meters] 2
19 20 21 22 23 24 25 26 27 28 29 30 35 40
Height (inches) Weight(pounds)
58 91 96 100 105 110 115 119 124 129 134 138 143 167 191
59 94 99 104 109 114 119 124 128 133 138 143 148 173 198
60 97 102 107 112 118 123 128 133 138 143 148 153 179 204
61 100 106 111 116 122 127 132 137 143 148 153 158 185 211
62 104 109 115 120 126 131 136 142 147 153 158 164 191 218
63 107 113 118 124 130 135 141 146 152 158 163 169 197 225
64 110 116 122 128 134 140 145 151 157 163 169 174 204 232
65 114 120 126 132 138 144 150 156 162 163 174 180 210 240
66 118 124 130 136 142 148 155 161 167 173 179 186 216 247
67 121 127 134 140 146 153 159 166 172 178 185 191 223 255
68 125 131 138 144 151 158 164 171 177 184 190 197 230 262
69 128 135 142 149 155 162 169 176 182 189 196 203 236 270
70 132 139 146 153 160 167 174 181 188 195 202 207 243 278
71 136 143 150 157 165 172 179 186 193 200 208 215 250 286
72 140 147 154 162 169 177 184 191 199 206 213 221 258 294
73 144 151 159 166 174 182 189 197 204 212 219 227 265 302
74 148 155 163 171 179 186 194 202 210 218 225 233 272 311
75 152 160 168 176 184 192 200 208 216 224 232 240 279 319
76 156 164 172 180 189 197 205 213 221 230 238 246 287 328

However, such tables are only rough guidelines. They cannot tell excess fat from muscle, so a very muscular person might appear to be obese using the information from this table when this is not the case.

Body mass index (BMI)

Another method doctors use for adults is body mass index (BMI), a mathematical formula that includes a person's height and weight. BMI equals a person's weight in kilograms divided by height in meters squared (BMI = kg/m 2 ). Like weight-for-height tables, BMI is only a rough estimate that does not tell muscle from fat. In general, though, a BMI of 25 or more can be a sign of obesity in people ages 19 to 34. A BMI of 27 or more can be a sign of obesity in people ages 35 or older. A BMI of more than 30 can be a sign of moderate to severe obesity. BMI should not be used for growing children, pregnant or breast-feeding women, body builders, competitive athletes, or elderly people who are both inactive and frail.

Waist-to-hip ratio

Doctors are concerned not only with how much fat an adult has, but also where that fat is located on the body. People whose fat is carried mostly around the belly, rather than on the hips, are more likely to develop many health problems linked to obesity. To find out which people have this body shape, doctors use the waist-to-hip ratio, which equals a person's waist measurement divided by the hip measurement. The health risks of obesity are higher in women with ratios of more than 0.8 and men with ratios of more than 1.0.

How Is Obesity Treated?

Research shows that the best way for people of all ages to control their weight is through regular exercise and a balanced diet. Adults can improve their health by losing as little as 10 to 20 pounds. To lose weight, people must take in fewer calories than they use. They can do this by becoming more active or eating less. The best weight-loss programs combine both of these approaches and also teach people healthy habits that they can follow for the rest of their lives.


Studies show that regular physical activity, combined with a good diet, is the healthiest and most effective way to control weight. Exercise uses excess calories that would otherwise be stored as fat.

Aerobic (air-O-bik) exercises are any extended activities that make a person breathe harder while using the large muscles at a regular, even pace. Such exercises burn more calories than other activities. They also strengthen the heart and lungs. Examples include brisk walking, jogging, bicycling, lap swimming, aerobic dancing, and using a treadmill or stationary bike. For the best results, aerobic exercise should be done for 20 to 30 minutes at a time, three or more times a week. People who are out of shape should start out exercising slowly.

Muscle strengthening exercises, such as weight training, and stretching exercises should also be part of a balanced exercise program. In addition to burning calories, these activities strengthen the muscles and bones and help prevent injury. Such exercises should be done at least twice a week.


Children should never go on a diet to lose weight, unless a doctor tells them to do so for medical reasons. Limiting what children eat can interfere with their growth and may be harmful to their health. Instead, children should shift to eating better foods, with most coming from the grain, vegetable, and fruit groups. Some foods from the milk and the meat and bean groups should also be included. Junk foods, which provide few vitamins and minerals but are full of fat and sugar, should be eaten sparingly or avoided altogether. Fat should not be restricted in the diet of very young children. By the time children are five years old, however, they should get no more than 30 percent of their total calories from fat. Simple ways to cut back on fat include eating low-fat or nonfat dairy products, lean meats, and other low-fat or fat-free foods.

Adults who are trying to lose weight often go on low-calorie diets. Such diets typically contain 1,000 to 1,500 calories a day. The exact number of calories that is right depends on a person's size and activity level. The goal should be to lose no more than one pound a week while still eating a varied diet that includes plenty of grains, vegetables, fruits, and other healthful foods.

Big Successes

These are just a few of the big names from history who had obesity:

  • Louis Armstrong (1900-1971).American jazz musician.
  • Sir Winston Churchill (1874-1965).British prime minister.
  • Benjamin Franklin (1706-1790).American statesman and author.
  • Jackie Gleason (1916-1987). American comedian and actor.
  • Alfred Hitchcock (1899-1980). British-born American film director.
  • Golda Meir (1898-1978). Israeli prime minister.
  • Babe Ruth (1895-1948). American baseball player.
  • William Howard Taft (1857-1930).American president.

Other treatments

Doctors may also treat severe obesity in other ways:

  • Very low-calorie diets. These are specially prepared formulas that contain no more than 800 calories a day and replace all other foods. Such diets can lead to faster weight loss than ordinary low-calorie diets. Since they can cause side effects, however, they should only be used under a doctor's guidance.
  • Drugs. Doctors can prescribe drugs to help adults with obesity who are apt to have health problems caused by their weight. Most drugs work by decreasing appetite or by increasing the feeling of being full. Such drugs are not magic, however. They are usually meant for short-term use over a few weeks or months, and they should always be part of an overall program that stresses long-term changes in exercise and diet. These drugs have the potential for abuse and can be addictive. They can also cause serious side effects, such as high blood pressure and sleep problems.
  • Surgery. Doctors may advise surgery for people who are extremely overweight. There are two types of weight-loss surgery. One limits the amount of food the stomach can hold by closing off or removing part of the stomach. The other causes food to be poorly digested by bypassing the stomach or part of the intestines. Right after surgery, most people lose weight quickly. Although some weight is often regained later, many people keep much of it off. Unfortunately, surgery itself can cause complications that may lead to medical problems or the need for further operations. In addition, surgical treatment for obesity can reduce the amount of vitamins and minerals in the body and cause gallstones.

Heavy-Hiffing Hints

It does not help much for a person to lose lots of weight only to regain it again. Keeping weight off is the toughest part of a weight-loss program for most people. The key to people keeping pounds off after they have been lost or stopping obesity before it starts is to learn healthy habits that last a lifetime. Here are some hints:

  • Get moving. Turn off the television, computer, and video games in favor of more active things to do. Have fun with friends and family by sharing activities that are good exercise, such as walking, dancing, or bicycling. In addition, look for other ways to become more active throughout the day. For example, walk around during school breaks, and take the stairs instead of the elevator.
  • Eat slowly. This makes it easier for a person to recognize feelings of hunger and fullness. One way for a person to slow down at meals is to make the meals as pleasant as possible. If meals are stressful, a person is tempted to eat faster in order to leave the table sooner.
  • Snack wisely. Unplanned snacking often leads to overeating. Planned snacks at particular times of the day can be part of a balanced diet without spoiling the appetite at mealtimes. It is also important to choose healthy snacks, such as fresh fruit, raw vegetables, and low-fat yogurt.
  • Avoid eating in front of the television or computer. People who are paying attention to a television or a computer are less likely to pay attention to feelings of fullness, and therefore may eat too much.



Bennett, Cherie. Life in the Fat Lane. Laureleaf, 1999. A novel about the high school experiences of a girl from the wrong side of the scales.

Kirby, Jane. Dieting for Dummies. Foster City, CA: IDG Books Worldwide, 1998. A book from the American Dietetic Association.

Manheim, Camryn. Wake Up, I'm Fat! New York: Broadway Books, 1999. A memoir by a successful actress who wears a size 22 dress.


Weight-Control Information Network, 1 WIN Way, Bethesda, MD 20892-3665. A service of the U.S. National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK).
Telephone 800-946-8098

The U.S. Centers for Disease Control and Prevention (CDC) posts a fact sheet about obesity at its website.

American Dietetic Association, 216 West Jackson Boulevard, Suite 800, Chicago, IL 60606-6995. A group that offers sound advice about healthy eating.
Telephone 800-366-1655

Shape Up America!, 6707 Democracy Boulevard, Suite 306, Bethesda, MD 20817. A group that offers up-to-date information about healthy weight and increased exercise.

TOPS Club, 4575 South Fifth Street, Milwaukee, WI 53207-0360. A club for people of all ages who are trying to Take Off Pounds Sensibly (hence, the name).
Telephone 800-932-8677

See also
Breast Cancer
Colorectal Cancer
Eating Disorders
Heart Disease
Prostate Cancer
Sleep Apnea

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