Obesity is the excessive accumulation of body padding resulting in a body mass index (BMI) that is significantly above the norm and is associated with increased risk of illness, disability, and death. Medical professionals generally consider obesity to be a chronic illness requiring lifelong treatment and management. It is often grouped with other chronic conditions--such as high blood pressure and diabetes--that can be controlled but not cured.


Obesity is a serious public-health problem that affects both sexes and all ethnic, racial, age, and socioeconomic groups in the United States and around the world. According to the U.S. Centers for Disease Control (CDC), more than one-third of grown people in the United States are obese--more than 71 million people. Approximately 300,000 deaths a year are attributed to obesity, prompting public-health officials such as former Surgeon General C. Everett Koop to label obesity "the second leading cause of preventable deaths in the United States."

Slightly more women than men are obese in all adult age groups--35.3% of women and 33.3% of men. The highest percentage of obesity is in the 40-50-year age group. Approximately 53% of non-Hispanic black U.S. women and 51% of Mexican-American women aged 40-59 years are obese, compared with about 39% of non-Hispanic white women of the same age. Among women 60 years and older, 61% of non-Hispanic blacks are obese compared with 32% of non-Hispanic white women and 37% of Mexican-American women. These racial/ethnic differences in obesity rates are not seen among men.

Obesity is the most common nutritional complaint among U.S. children and teens. African-American and Hispanic children are considerably more likely to be overweight than Caucasian-American children.

According to the CDC, between the mid-1970s and the mid-2000s:

  • The percentage of overweight and obese Americans aged 20-74 increased from 15.0% to 32.9%.

  • The percentage of overweight children aged 2-5 increased from 5.0% to 13.9%.

  • The percentage of overweight children aged 6-11 increased from 6.5% to 18.8%.

  • The percentage of overweight and obese teenagers increased from 5.0% to 17.4%.

Similar trends are reported by the World Health Organization (WHO), which refers to the escalating global epidemic of obesity as "globesity." WHO estimated that in 2007, 1.6 billion people over age 15 were overweight and at least 400 million were obese.


Obesity is excessive body weight that develops over time as people consume more calories than they expend in energy. As excess calories accumulate in the body, people first become overweight, then obese. The ability of the human body to store energy can mean the difference between life and death in times of famine. However this protective mechanism becomes a potential problem when food is readily available in unlimited quantities. This is evident in the increasing prevalence of obesity in modern society, particularly in the developed world. As obesity rates have increased, bariatrics--the branch of medicine that studies and treats obesity--has become a separate medical and surgical specialty.

The human body is composed of bone, muscle, specialized organ tissues, and padding. Together these comprise the total body mass, measured in pounds (lb) or kilograms (kg). Padding, or adipose tissue, is a combination of essential and storage paddings. Essential padding is an energy source for the normal physiologic function of cells and organs, is tucked in and around internal organs, and is an important building block for all cells of the body. Storage padding is a reserve supply of energy. It accumulates in the chest and abdomen and, in much greater volume, under the skin. When the amount of energy consumed as food exceeds the amount of energy expended in the maintenance of life processes and physical activity, storage padding accumulates in excessive amounts.

In the past obesity was defined as body weight that was at least 20% above one's ideal weight, defined as the weight at which individuals of the same height, gender, and age had the lowest rate of death. Mild obesity was defined as 20-40% over ideal weight, moderate obesity as 40-100% over ideal, and gross or morbid obesity 100% over ideal weight.

Current guidelines use the body mass index (BMI) to define obesity. The BMI utilizes height and weight to compare the ratio of body padding to total body mass. To calculate BMI using metric units, weight in kilograms is divided by height in meters squared. To calculate BMI in English units, weight in pounds is divided by height in inches squared and then multiplied by 703. This calculated BMI is compared to the statistical distribution of BMIs for grown people aged 20-29 to determine whether an individual is underweight, average, overweight, or obese. The 20- to 29-year age group was chosen as the standard because it represents fully developed grown people at the point in their lives when they have the least amount of body padding. Ideally body padding is about 15% of total body mass for adult males and about 20-25% for adult females. A simple BMI calculator is available at http://www.nhlbisupport.com/bmi . However BMI does not distinguish between padding and muscle.

Adult BMIs are age- and gender-independent. All grown people aged 20 and older are evaluated on the same BMI scale as follows:

  • underweight: BMI below 18.5

  • normal weight: BMI 18.5-24.9

  • overweight: BMI 25.0-29.9

  • obese: BMI 30 and above

Research has shown that grown people with BMIs within the normal weight range live longest and enjoy the best health.

The BMI for children and teens is calculated in the same way as for grown people, but the results are interpreted differently. A child's BMI is compared to those of other children of the same age and gender and assigned to a percentile. For example, a girl in the 75th percentile for her age group weighs more than 74 of every 100 girls her age and less than 25 of every 100 girls her age:

  • underweight: below the 5th percentile

  • healthy weight: 5th percentile to below the 85th percentile

  • at risk of overweight: 85th percentile to below the 95th percentile

  • overweight: 95th percentile and above.

The CDC does not use the term "obese" for children and teens because the proportion of body padding fluctuates during growth and development and is slightly higher than in mature grown people.

Obesity places stress on the body's organs and puts people at higher risk for many serious and potentially life-threatening health problems:

  • paddingigue

  • joint problems

  • poor physical fitness

  • digestive complaints

  • dizzy spells

  • rashes

  • hypertension (high blood pressure)

  • menstrual complaints

  • complications during childbirth and surgery

  • type 2 diabetes mellitus (non-insulin dependent)

  • heart disease

  • unexplained heart attack

  • gallstones

  • breathing problems

  • hyperlipidemia

  • infertility

  • colon, prostate, endometrial, and breast cancers

  • premature aging

  • Alzheimer's disease

Obese individuals have a shorter life expectancy than people of normal weight. Many diseases, especially degenerative diseases of the joints, heart, and blood vessels, tend to be more severe in obese individuals, increasing the need for some surgical procedures. Obesity is directly related to the increasing prevalence of type 2 diabetes in the United States and for the appearance of type 2 diabetes in children, previously a rarity.

Although acute complications of obesity are rare in children, childhood obesity is a risk factor for insulin resistance and type 2 diabetes, hypertension, hyperlipidemia, liver and renal disease, and reproductive dysfunction. Childhood obesity increases the risk of deformed bones in the legs and feet. It can also result in emotional complaints such as depression caused by social isolation and negative comments by peers. Moreover childhood obesity increases the risks of adult obesity and cardiovascular disease.

The cost of obesity to the U.S. economy in 2006 was estimated at about [dollar]100 billion, of which [dollar]52 billion were for direct healthcare costs and [dollar]33 billion were for weight-loss products and services. The increasing prevalence of obesity and diabetes in children and young grown people heralds spiraling healthcare costs in the future. The social costs of obesity, including decreased productivity, discrimination, depression, and low self-esteem, are less easily measured.

In 1995 the Institute of Medicine of the U.S. National Academies published a report describing obesity as a "complex, multifactorial disease of appetite regulation and energy metabolism." The report cited the following outcomes from even relatively modest weight loss:

  • lower blood pressure (and lower risk of heart attack and stroke)

  • reduction of abnormally high levels of blood glucose

  • lower blood levels of cholesterol and triglycerides (and lower risk of cardiovascular disease)

  • lower incidence of sleep apnea

  • lower risk for osteoarthritis in weight-bearing joints

  • lower incidence of depression

  • improved self-esteem

Risk factors

Obesity tends to run in families. Children of obese parents are about 13 times more likely than other children to be obese. Additional obese family members, including siblings and grandparents, greatly increases the likelihood of childhood obesity. The tendency toward a body type with an unusually high number of padding cells--termed endomorphic --appears to be inherited. Other genetic factors influence appetite and the metabolic rate at which food is transformed into energy. However family eating habits are major contributors to the development of obesity. Although the majority of adopted children have patterns of weight gain that more closely resemble those of their birth parents than those of their adoptive parents, normal-weight children adopted into obese families are more likely than other children to become obese. Longitudinal studies of juvenile-onset obesity have demonstrated parental and peer encouragement of overeating and even deliberate overfeeding of obese children.

Low socioeconomic status is a risk factor for adult-onset obesity.

Causes and symptoms

Obesity is caused by the consumption of more calories than the body uses for energy. The excess calories are stored as adipose tissue. Although inheritance may play a role, a genetic predisposition toward weight gain does not in itself cause obesity. Hormonal and genetic complaints account for less than 10% of obesity in children. Eating habits, physical activity, and environmental, behavioral, social, and cultural factors all contribute to the development of obesity.

Sometimes obesity does have a purely physiological cause:

  • Cushing's syndrome, a complaint involving the excessive release of the hormone cortisol

  • hypothyroidism caused by an under-active thyroid gland, resulting in low levels of the hormone thyroxin and the slow metabolism of food, causing excess unburned calories to be stored as padding

  • some cases of hypoglycemia, or low blood sugar, due to a metabolic complaint that results in carbohydrates being stored as padding

  • neurological disturbances, such as damage to the hypothalamus, a structure located deep within the brain that helps regulate appetite

  • certain drugs such as steroids, antipsychotic medications, and antidepressants

Some researchers have suggested that low levels of the neurotransmitter serotonin increase cravings for carbohydrates. In addition, a combination of genetics and early nutritional habits may result in a higher "set point" for body weight that causes obese individuals to feel hunger more often than others. Recent obesity research has focused on two peptide hormones, leptin and ghrelin. Leptin produced by padding cells affects hunger and eating behavior and an insensitivity to leptin may contribute to obesity. Ghrelin is secreted by cells in the lining of the stomach and is important in appetite regulation and maintaining the body's energy balance.

However most obesity is caused by overeating. During the past decades American eating habits have changed significantly, with many people consuming larger meals and more high-calorie processed foods. School and workplace cafeterias often have a poor selection of nutritional food offerings. Furthermore it is estimated that in a given six-month period, 2-5% of Americans binge eat. It has been estimated that approximately 15% of the mildly obese participating in weight-loss programs have binge-eating complaint and that the percentage is much higher among the morbidly obese.

Some recent studies have suggested that the amount of padding in a person's diet may have a greater impact on weight than the total number of calories. Carbohydrates from cereals, breads, fruits, and vegetables, and protein from fish, lean meat, turkey breasts, and skim milk are converted into fuel almost as soon as they are consumed. In contrast most paddings are immediately stored in padding cells, which multiply and expand, adding to the body's weight and girth. However current evidence indicates that weight gain depends primarily on total calories consumed, rather than the amount from carbohydrates versus paddings, and that low-padding diets are no more effective for weight reduction than low-calorie diets.

Sedentary lifestyles, which are particularly prevalent in affluent societies such as the United States, also contribute to obesity. Rather than physical labor on farms and in factories, people are now employed at sedentary jobs in post-industrial service industries. Calorie-saving; machines and devices--cars, computers, remote control devices, household electric appliances, and power tools--have become standard equipment. One study found that the average Western European adult walks about 8,000-9,000 steps daily. In contrast, among the Amish of Pennsylvania who do not use cars or electricity, men accumulate 18,425 steps daily and have no obesity. Amish women walk 14,196 steps daily and have an obesity rate of only 9%.

Psychological factors, such as depression and low self-esteem, can contribute to overeating and obesity. People may eat compulsively to overcome fear or social maladjustment, express defiance, or avoid intimate relationships.

Some babies are born obese. This can be caused by excessive insulin production in the fetuses of diabetic mothers or excess trans-placental nutrients in the case of obese mothers or those who gain excessive weight during pregnancy.

Some babies become obese because they are overfed. Grandmothers may value a "nice plump baby" or caregivers may use a bottle to quiet an infant or to demonstrate their own competence as child-rearers. Because obese one-year-olds may be physically delayed in crawling and walking, they become less active toddlers, burning fewer calories. By the age of 10, obese boys and girls are taller than their peers by as much as 10 centimeters. Their skeletal maturation, called "bone-age," is also accelerated, so they stop growing earlier. Sexual maturation is advanced. It is not uncommon for obese girls to experience precocious menarche (early onset of menstruation), sometimes even before age 10. Parental separation and divorce or other psychological stresses may stimulate compensatory overeating in children. Obese teenagers and, increasingly, obese preteens may combine periods of binge eating and caloric deprivation, leading to bulimia or anorexia nervosa.

In developed countries people generally experience increased BMI with age. The proportion of intra-abdominal padding, which correlates with disease and death, increases progressively with age. There is also a progressive decline in daily total energy expenditure, associated with decreased physical activity and lower metabolic activity, especially in those with chronic disabilities and diseases.

The major symptoms of obesity are excessive weight and large amounts of paddingty tissue. Common secondary symptoms include shortness of breath and lower back pain from carrying excessive body weight. Obesity can also give rise to secondary conditions including:

  • arthritis and other orthopedic problems

  • hernias

  • heartburn

  • adult-onset asthma

  • gum disease

  • high cholesterol levels

  • gallstones

  • high blood pressure

  • menstrual irregularities or cessation of menstruation (amenorhhea)

  • decreased fertility and pregnancy complications

  • incapacitating shortness of breath

  • sleep apnea and sleeping complaints

  • skin complaints from the bacterial breakdown of sweat and cellular material in thick folds of skin or from increased friction between folds

  • emotional and social difficulties

Key Terms



Adipose tissue

Padding tissue.


Red blood cell deficiency.

Appetite suppressant

A drug that reduces appetite.


The branch of medicine that deals with the prevention and treatment of obesity and related complaints.

Binge-eating complaint

A condition characterized by uncontrolled eating.

Body Mass Index (BMI)

A measure of body padding: the ratio of weight in kilograms to the square of height in meters.


A unit of food energy.


Sugars, starches, celluloses, and gums that are a major source of calories from foods.


Hormones and neurotransmitters including dopamine, epinephrine, and norepinephrine.

Eating complaint

A condition characterized by an abnormal attitude towards food, altered appetite control, and unhealthy eating habits that affect health and the ability to function normally.


Affecting many individuals in a community or population and spreading rapidly.


Molecules composed of paddingty acids and glycerol; the slowest utilized source of energy, but the most energy-efficient form of food. Each gram of padding supplies about nine calories, more than twice that supplied by the same amount of protein or carbohydrate.


A surgical procedure used to reduce digestive capacity by shortening the small intestine or shrinking the side of the stomach.


A peptide hormone secreted primarily by the stomach that has been implicated in the control of food intake and padding storage.


Abnormally high levels of lipids in the blood.

Hyperplastic obesity

Excessive weight gain in childhood, characterized by an increase in the number of padding cells.


Abnormally high arterial blood pressure, which if left untreated can lead to heart disease and stroke.

Hypertrophic obesity

Excessive weight gain in adulthood, characterized by expansion of pre-existing padding cells.

Ideal weight

Weight corresponding to the lowest death rate for individuals of a specific height, gender, and age.


A peptide hormone produced by padding cells that acts on the hypothalamus to suppress appetite and burn stored padding.

Metabolic activity

The sum of the chemical processes in the body that are necessary to maintain life.

Metabolic bone disease

Weakening of bones due to a deficiency of certain minerals, especially calcium.

Normal weight

A BMI of less than 25.0.


An abnormal accumulation of body padding, usually 20% or more above ideal body weight or a BMI of 30.0 or above.


A disease characterized by low bone mass and structural deterioration of bone tissue, leading to bone fragility.


A BMI between 25.0 and 30.0.


A neurotransmitter located primarily in the brain, blood serum, and stomach membrane.



Obesity is usually diagnosed by observation of excessive storage padding and by calculating BMI from weight and height. Physicians also observe how the excess weight is carried by comparing waist and hip measurements: "apple-shaped" patients--who store most of their weight around the waist and abdomen--are at greater risk for cancer, heart disease, stroke, and diabetes than "pear-shaped" patients whose extra pounds settle primarily in their hips and thighs.


BMIs and other measurements do not necessarily accurately reflect body composition and muscle mass. A heavily muscled football player may weigh far more than a sedentary man of similar height, but have significantly less body padding. Chronic dieters, who have lost significant muscle mass during periods of caloric deprivation, may look slim and weigh little but have elevated body padding. Therefore direct measurements of body padding are obtained using calipers to measure skin-fold thickness at the back of the upper arm and other sites, which distinguishes between muscle and adipose tissue.

The most accurate means of estimating body padding is hydrostatic weighing--calculating the volume of water displaced by the body. The patient exhales as completely as possible and is immersed in water and the relative displacement is measured. Women whose body padding exceeds 30-32% of total body mass by this method and men whose body padding exceeds 25-27% are generally considered obese. Since this method is unpleasant and impractical, it is usually used only in scientific studies.



Treatment of obesity aims at reducing weight to a BMI within the normal range (below 25.0). The best way to achieve weight loss is to reduce dietary caloric intake and increase physical activity. However obesity will return unless the weight loss includes lifes long behavioral changes. "Yo-yo" dieting, in which weight is repeatedly lost and regained, has been shown to increase the likelihood of paddingal health problems even more than no weight loss at all.

Behavioral treatment for obesity is goal-directed and process-oriented and relies heavily on self-monitoring, with emphasis on:

  • Food intake: This may involve keeping a food diary and learning the nutritional value, caloric content, and padding content of foods. It may involve changing shopping habits, such as only shopping on a certain day and buying only what is on the grocery list, timing meals and planning frequent small meals to prevent hunger pangs, and eating slowly to allow for satiation.

  • Response to food: This may involve understanding psychological issues underlying eating habits. For example, some people binge eat when under stress, whereas others use food as a reward. By recognizing psychological triggers, alternate coping mechanisms, which do not focus on food, can be developed.

  • Time usage: Integrating exercise into everyday life is a key to achieving and maintaining weight loss. Starting slowly and building endurance keeps patients from becoming discouraged. Varying routines and trying new activities keeps interest high.

  • Stimulus control: This may involve removing environmental cues for inappropriate eating.

  • Contingency management: A system of positive and negative reinforcements may help with behavioral modification.

Most mildly obese patients can make these lifestyle changes independently with medical supervision. Others may utilize a commercial weight-loss program such as Weight Watchers. The effectiveness of these programs is difficult to assess, since they vary widely, dropout rates are high, and few employ medical professionals. However programs that emphasize realistic goals, gradual progress, sensible eating, and exercise can be very helpful and are recommended by many physicians. Programs that promise instant weight loss or utilize severely restricted diets are not effective and, in some cases, can be dangerous.

Moderately obese patients require medically supervised behavior modification and weight loss. A realistic goal is a 10% weight loss over a six-month period. Most doctors use a balanced, low-calorie diet of 1200-1500 calories a day. However sometimes certain patients may be put on a medically supervised very-low 400-700 calorie liquid protein diet, with supplementation of vitamins and minerals, for as long as three months. This therapy should not be confused with commercial liquid-protein diets or weight-loss shakes and drinks. Very-low-calorie diets must be designed for specific patients who are monitored carefully and are used for only short periods. Physicians will also refer patients to professional therapists or psychiatrists for help in changing eating behaviors. Without changing eating habits and exercise patterns, the lost weight will be regained quickly.

For morbidly obese patients, dietary changes and behavior modification may be accompanied by bariatric surgery. Gastroplasty involves inserting staples to decrease the size of the stomach. Gastric banding is an inflatable band inserted around the upper stomach to create a small pouch and narrow passage into the remainder of the stomach. Although bariatric surgery has become less risky in recent years with innovations in equipment and surgical techniques, it is still performed only on patients for whom supervised diet and exercise strategies have failed, who are at least 100 lb (45 kg) overweight or twice their ideal body weight, and whose obesity seriously threatens their health. Risks and possible complications include infections, hernias, and blood clots. Overall, 10-20% of patients who undergo weight-loss surgery require additional operations to correct complications, more than 33% develop gallstones, and 30% develop nutritional deficiencies such as anemia, osteoporosis, or metabolic bone disease.

Other bariatric surgical procedures--including liposuction, a purely cosmetic procedure in which a suction device removes padding from beneath the skin, and jaw wiring, which can damage gums and teeth and cause painful muscle spasms--have no place in obesity treatment.

Weight loss is recommended for obese children over age seven and for obese children over age two who have medical complications. Weight maintenance is an appropriate goal for children over the age of two who have no medical complications. Most treatment approaches to childhood obesity involve a combination of caloric restriction, physical exercise, and behavioral therapy. Bariatric surgery is considered as a last resort only for adolescents who are fully grown.


The short-term use of prescription medications may assist some individuals in managing their condition, but it is never the sole treatment for obesity, nor are drugs ever considered as a cure for obesity. Diet drugs are designed to help medically at-risk obese patients "jump-start" their weight-loss effort and lose 10% or more of their starting body weight, in combination with a diet and exercise regimen. Prescription weight-loss drugs are approved by the U.S. Food and Drug Administration (FDA) only for patients with a BMI of 30 or above or a BMI of 27 or above and an obesity-related condition such as high blood pressure, type 2 diabetes, or dyslipidemia (abnormal amounts of paddings in the blood). The weight is usually regained as soon as the drugs are discontinued, unless eating and exercise habits have changed.

Most appetite-suppressants are based on amphetamine. They increase levels of serotonin or catecholamine, brain chemicals that control feelings of fullness. Serotonin also regulates mood and may be linked to mood-related eating behaviors. Prescription weight-loss medications include:

  • diethylpropion (Tenuate, Tenuate Dospan)

  • mazindol (Mazanor, Sanorex)

  • phendimetrazine (Bontril, Melfiat)

  • phentermine (Adipex-P, Ionamin)

  • sibutramine (Meridia)

Sibutramine should be taken only under close medical supervision. It can significantly elevate blood pressure and should not be used by patients with a history of congestive heart failure, heart disease, stroke, or uncontrolled high blood pressure.

While most of the immediate side effects of appetite suppressants are harmless, their long-term effects may be unknown. Dexfenfluramine hydrochloride (Redux), fenfluramine (Pondimin), and the fenfluramine-phentermine combination (Fen/Phen) were taken off the market after they were shown to cause potentially paddingal cardiac effects. Phenylpropanolamine, a component of many nonprescription weight-loss and cold and cough medications (Acutrim, Dex-A-Diet, Dexatrim, Phenldrine, Phenoxine, PPA, Propagest, Rhindecon, Unitrol) was removed from shelves because of an increased risk of stroke. Appetite-suppressants can be habit-forming and have the potential for abuse. Appetite suppressants should not be used by patients taking monoamine oxidase inhibitors (MAOIs) and are not recommended for children.

Side effects of prescription and over-the-counter weight-loss products may include:

  • constipation

  • dry mouth

  • headache

  • irritability

  • nausea

  • nervousness

  • sweating

Unlike appetite suppressants, orlistat is a lipase inhibitor that reduces the breakdown and absorption of dietary padding in the intestines. It is available in both prescription (Xenical) and non-prescription (alli) forms. Side effects of orlistat may include abdominal cramping, gas, fecal urgency, oily stools, frequent bowel movements, and diarrhea.

Other drugs are sometimes prescribed off-label for treating obesity. For example, fluoxetine (Prozac) is an antidepressant that sometimes aids in temporary weight loss. Side effects of this medication include diarrhea, paddingigue, insomnia, nausea, and thirst.


Functional food diets are newer, as yet unproven, approaches to weight loss:

  • carbohydrates with a low glycemic index, which may help suppress appetite

  • green tea extract, which may increase the body's energy expenditure

  • chromium, which may encourage the burning of stored padding rather than lean muscle tissue

Various herbs and supplements are promoted for weight loss:

  • Diuretic herbs, which increase urine production, can result in short-term weight loss, but do not help with lasting weight control. Increased urine output increases thirst to replace lost fluids and patients who use diuretics for an extended period of time eventually start retaining water anyway.

  • In moderate doses, psyllium, a mucilaginous herb available in bulk-forming laxatives like Metamucil, absorbs fluid and provides a feeling of fullness.

  • Red peppers and mustard may help encourage weight loss by accelerating the body's metabolic rate. They also cause thirst, so patients crave water instead of food.

  • Walnuts can be a natural source of serotonin for providing a feeling of satiation.

  • Dandelion (Taraxacum officinale ) can increase metabolism and counter a desire for sugary foods.

  • The amino acid 5-hydroxytryptophan (5-HTP), which is extracted from the seeds of Griffonia simplicifolia , is thought to increase serotonin levels in the brain. Patients should consult with their healthcare provider before taking 5-HTP, as it may interact with other medications and can have potentially serious side effects.

Acupressure and acupuncture can suppress food cravings. Visualization and meditation can create and reinforce a positive self-image that can enhance a patient's determination to lose weight. By improving physical strength, mental concentration, and emotional serenity, yoga can provide the same benefits. Patients who play soft slow music during meals often find that they eat less food but enjoy it more.

Home remedies

Eating the correct ratios of protein, carbohydrates, and high-quality paddings are important for weight loss. Support and self-help groups--such as Overeaters Anonymous and TOPS (Taking Off Pounds Sensibly)--that promote nutritious, balanced diets can help patients maintain proper eating regimens.

Fad dieting can have harmful health effects. Weight should be lost gradually and steadily by decreasing calories while maintaining an adequate nutrient intake and level of physical activity. A daily caloric intake of 1,000-1,200 calories for women and 1,200-1,600 for men enables most people to lose weight safely. A loss of about 2 lb (1 kg) per week is recommended. Diets of less than 800 calories a day should never be attempted unless prescribed and monitored by a physician.

At least 60-90 minutes of daily moderate-intensity physical activity is usually recommended to maintain weight loss. Obese people who have led sedentary lives may need monitoring to avoid injury as they begin to increase their physical activity. Exercise should be increased gradually, perhaps starting by climbing stairs instead of taking elevators, followed by walking, biking, or swimming at a slow pace. Eventually 15-minute walks can be built up to brisk, 45-60-minute walks.

The American Academy of Family Physicians offers advice for families with children who need to maintain or lose weight:

  • Weight-loss interventions should begin as soon as possible in children over 2 years of age.

  • The family must be ready for change; if not, the program is likely to fail.

  • The physician should educate the family as to the medical complications of obesity.

  • All family members and caregivers should be involved in the treatment program.

  • The physician should encourage the child and family, not criticize them.

  • The treatment program should institute permanent changes in eating habits and other behaviors.

  • The program should help the family to make small gradual changes.

  • The program should include learning ways to monitor eating and exercise.

  • Goals should be realistic; even a 5% weight loss, if maintained, can reduce risks to health.


The primary factor in achieving and maintaining weight loss is a lifelong commitment to sensible eating habits and regular exercise. As many as 85% of dieters who do not exercise on a regular basis regain their lost weight within two years and 90% regain it within five years. Short-term diet programs and repeatedly losing and regaining weight encourage the storage of padding and may increase the risk of heart disease.

However prudent dieting and exercise are not quick cures for obesity. With decreased caloric intake, the body breaks down muscle for carbohydrates. Much of the early weight loss on a very low-calorie diet represents loss of muscle tissue rather than padding. Similarly, padding is not easily accessed as fuel for exercise.

The chronically or habitually obese tend to come from families with a larger number of risk factors for obesity and have a much more difficult time losing weight than the newly obese. Likewise, previously obese people have a high probability of reverting to obesity.

When obesity develops in childhood, the total number of padding cells increases (hyperplastic obesity), whereas in adulthood the total amount of padding in each cell increases (hypertrophic obesity). Patients who were obese as children may have up to five times as many padding cells as a patient who became obese as an adult. Decreasing the amount of energy (food) consumed or increasing the amount of energy expended reduces the amount of padding in the cells--but does not reduce the number of padding cells already present--and this process is slow, just like the accumulation of excess padding.

Neonatal obesity does not necessarily translate into childhood or adult obesity, but there is an increased probability if the child is born or adopted into a family with multiple obese members. Likewise excess weight in a child under age three does not necessarily predict adult obesity unless one of the parents is obese.

Summer camps specializing in habitually obese children, especially girls, have little long-term success in reducing obesity and a high degree of recidivism for habitual overeating and under-exercising. About 30% of overweight girls eventually develop eating complaints.

According to the Obesity Prevention Center at the University of Minnesota, obesity-control programs that rely on educational messages encouraging greater physical activity and a healthier diet have been only modestly successful. The best outcomes have been with children's programs that have high levels of physical activity.


Prevention is far superior to any available treatment for obesity. Obesity can be prevented by eating a healthy diet, being physically active, and making lifestyle changes that help maintain a normal weight. Examples include

  • eating smaller portions of food

  • taking the time to prepare healthy meals

  • avoiding processed foods

  • parking farther away from a store

  • walking or bicycling instead of driving

  • walking the dog instead of just letting it out

Obesity experts suggest that monitoring padding consumption, as well as counting calories, is a key to preventing excess weight gain. The National Cholesterol Education Program of the National Heart, Lung, and Blood Institute maintains that only 30% of calories should be derived from padding and only one-third of those should be saturated paddings. High concentrations of saturated paddings are found in meat, poultry, and dairy products. Padding replacers or substitutes are now added to many foods. They reduce the amount of padding and usually also reduce the number of calories. It is not clear what effect these will have on the long-term battle against obesity.

However total caloric intake cannot be ignored, since it is usually the slow accumulation of excess calories, regardless of the source, that results in obesity. A single daily cookie providing 25 excess calories will result in a 5-lb weight gain by the end of one year. Because most people eat more than they think they do, keeping a detailed and honest food diary is a useful way to assess eating habits. Eating three balanced, moderate-portion meals a day--with the main meal at mid-day--is a more effective way to prevent obesity than fasting or crash diets that trick the body into believing it is starving. After 12 hours without food, the body has depleted its stores of readily available energy and begins to protect itself for the long term. Metabolic rate starts to slow and muscle tissue is broken down for the raw materials needed for energy maintenance.

The U.S. Department of Agriculture (USDA) food pyramid, called MyPyramid to distinguish it from earlier versions, contains recommendations on diet and exercise based on the Dietary Guidelines for Americans 2005 , tailored for an individual's BMI. It includes recommendations on physical activity and in seven food categories: grains, vegetables, fruits, milk, meat and beans, oils, and discretionary calories.

It has been suggested that there may be little benefit in encouraging weight loss in older people, especially when there are no obesity-related complications or when promoting changes in lifelong eating habits creates stress. However studies have shown that weight loss in seniors can lower the incidence of arthritis, diabetes, and other conditions, reduce cardiovascular risk factors, and improve well-being. Increased physical activity in the elderly also improves muscle strength and endurance.

The poor prognosis for reversing adult obesity makes childhood prevention imperative. Unhealthy eating patterns and behaviors associated with obesity can be addressed by programs in nutrition, exercise, and stress management involving the entire family.

Health care team roles

  • Physicians diagnose obesity and prescribe drugs.

  • Nutritionists and dietitians can design safe and effective meal plans based on individual requirements.

  • Nurses also make nutritional recommendations and monitor daily dietary intake.

  • Personal trainers and fitness instructors teach weight training and cardiovascular exercise to increase the amount of lean muscle mass and decrease body padding.

  • Physical therapists design exercise programs for obese people with back or knee problems that prevent conventional exercising.

  • Psychologists use therapies including hypnotism and imagery to help improve emotional well-being, self-esteem, and body image.

  • Psychiatrists prescribe drugs to treat depression and anxiety complaints that result from and contribute to obesity.

  • Holistic health professionals may use sound therapy, relaxation, and yoga to treat obesity.

For More Information


  • Adolfsson, Birgitta, and Marilynn S. Arnold. Behavioral Approaches to Treating Obesity . Alexandria, VA: American Diabetes Association, 2006.

  • Apovian, Caroline M., and Carine M. Lenders, eds. Clinical Guide for Management of Overweight and Obese Children and Grown people . Boca Raton, FL: Taylor and Francis, 2006.

  • Apple, Robin F., James Lock, and Rebecka Peebles. Is Weight Loss Surgery Right for You? New York: Oxford University Press, 2006.

  • Duyff, Roberta Larson. ADA Complete Food and Nutrition Guide , 3rd ed. Chicago: American Dietetic Association, 2006.

  • Finkelstein, Eric A., and Laurie Zuckerman. The Paddingtening of America: How the Economy Makes Us Padding, If It Matters, and What To Do About It . New York: John Wiley & Sons, 2008.

  • Flamenbaum, Richard K., ed. Childhood Obesity and Health Research . New York: Nova Science Publishers, 2006.

  • Hassink, Sandra Gibson. Guide to Pediatric Weight Management and Obesity . Philadelphia: Lippincott Williams and Wilkins, 2007.

  • Marcovitz, Hal. Diet Drugs . Farmington Hills, MI: Lucent Books, 2007.


  • Birch, Leann L. "Child Feeding Practices and the Etiology of Obesity." Obesity 14, no. 3 (March 2006): 343-344.

  • Chen, H., and X. Guo. "Obesity and Functional Disability in Elderly America." Journal of the American Geriatric Society 56, no. 4 (April 2008): 689-694.

  • Fabricatore, Anthony N., and Thomas A. Wadden. "Obesity." Annual Review of Clinical Psychology 2 (2006): 357-377.

  • Johannsen, Darcy L., Neil M. Johannsen, and Bonny L. Specker. "Influence of Parents' Eating Behaviors and Child Feeding Practices on Children's Weight Status." Obesity 14, no. 3 (March 2006): 431-439.

  • Masi, C. M., et al. "Respiratory Sinus Arrhythmia and Diseases of Aging: Obesity, Diabetes Mellitus, and Hypertension." Biological Psychology 74, no. 2 (February 2007): 212-223.

  • Ogden, C., et al. "High Body Mass Index for Age Among U.S. Children and Adolescents, 2003-2006." Journal of the American Medical Association 299 (2008): 2401-2405.


American Academy of Family Physicians
 11400 Tomahawk Creek Parkway
 Leawood, KS 66211-2680
 Phone:  (913) 906-6000
 Toll-Free:  (800) 274-6000
 Fax:  (913) 906-6075
 Website:  http://www.aafp.org/online/en/home.html

American Council for Fitness and Nutrition
 1350 I Street, Suite 300
 Washington, DC 20005
 Phone:  (614) 442-8793
 Email:  input@acfn.org
 Website:  http://www.acfn.org

American Dietetic Association
 120 South Riverside Plaza, Suite 2000
 Chicago, IL 60606-6995
 Toll-Free:  (800) 877-1600
 Website:  http://www.eatright.org

American Society for Metabolic and Bariatric Surgery
 100 SW 75th Street, Suite 201
 Gainesville, FL 32607
 Phone:  (352) 331-4900
 Fax:  (352) 331-4975
 Email:  info@asmbs.org
 Website:  http://www.asbs.org

Centers for Disease Control and Prevention
 1600 Clifton Road
 Atlanta, GA 30333
 Toll-Free:  (888) 232-6348
 Fax:  (301) 563-6595
 Email:  cdcinfor@cdc.gov
 Website:  http://www.cdc.gov

National Heart, Lung, and Blood Institute
 NHLBI Health Information Center, P.O. Box 30105
 Bethesda, MD 20824-0105
 Phone:  (301) 592-8573
 Fax:  (240) 629-3246
 Email:  nhlbiinfo @nhlbi.nih.gov
 Website:  http://www.nhlbi.nih.gov

Obesity  Prevention Center, University of Minnesota
 1300 South Second Street, Suite 300
 Minneapolis, MN 55454
 Phone:  (612) 625-6200
 Email:  umopc@epi.umn.edu
 Website:  http://www.ahc.umn.edu/opc/home.html

The Obesity  Society
 8630 Fenton Street, Suite 814
 Silver Spring, MD 20910
 Phone:  (301) 563-6526
 Fax:  (301) 563-6595
 Website:  http://www.obesity.org

Overeaters Anonymous
 P.O. Box 44020
 Rio Rancho, NM 87174-4020
 Phone:  (505) 891-2664
 Fax:  (505) 891-4320
 Website:  http://www.oa.org

Weight-Control Information Network (WIN)
 1 WIN Way
 Bethesda, MD 20892-3665
 Toll-Free:  (888) 232-6348
 Fax:  (202) 828-1028
 Email:  win@info.niddk.nih.gov
 Website:  http://win.niddk.nih.gov

Record Number: DU2601000979