obesity, condition resulting from excessive storage of fat in the body. Obesity has been defined as a weight more than 20% above what is considered normal according to standard age, height, and weight tables, or by a complex formula known as the body mass index. It has been estimated that 30% to 35% of Americans are overweight or obese.

Health and Social Implications

Obesity is a major public health concern because it predisposes the individual to many disorders, such as noninsulin-dependent diabetes diabetes or diabetes mellitus (məlī`təs)
..... Click the link for more information. , hypertension hypertension or high blood pressure, elevated blood pressure resulting from an increase in the amount of blood pumped by the heart or from increased resistance to the flow of blood through the small arterial blood vessels (arterioles).
..... Click the link for more information. , stroke stroke, destruction of brain tissue as a result of intracerebral hemorrhage or infarction caused by thrombosis (clotting) or embolus (obstruction in a blood vessel caused by clotted blood or other foreign matter circulating in the bloodstream); formerly called
..... Click the link for more information. , and coronary artery disease coronary artery disease, condition that results when the coronary arteries are narrowed or occluded, most commonly by atherosclerotic deposits of fibrous and fatty tissue.
..... Click the link for more information. , and has been associated with an increased incidence of certain cancers, notably cancers of the colon, rectum, prostate, breast, uterus, and cervix. In contemporary American society, obesity also carries with it a sometimes devastating social stigma. Obese people are often ostracized, and discrimination against them, especially in hiring and promotion, is common.

Causes of Obesity

Obesity research has yielded a complicated picture of the underlying causes of the condition. The simple cause is ingestion of more calories than are required for energy, the excess being stored in the body as fat. Inactivity and insufficient exercise can be contributing factors; the less active the person, the fewer calories are needed to maintain normal body weight. Overeating may result from unhealthful patterns of eating established by the family and cultural environment, perhaps exacerbated by psychological distress, an emotional dependence on food, or the omnipresence of high-calorie foods.

In some cases, obesity can come from an eating disorder eating disorders, in psychology, disorders in eating patterns that comprise four categories: anorexia nervosa, bulimia, rumination disorder, and pica. Anorexia nervosa is characterized by self-starvation to avoid obesity.
..... Click the link for more information. . It has been shown, for example, that binging for some people releases natural opiates in the brain, providing a sense of well-being and physical pleasure. Other studies have found a strong relationship between obesity in women and childhood sexual abuse.

Some weight-loss experts see obesity as based upon genetics and physiology rather than as a behavioral or psychological problem. For example, rat studies have shown that fat cells secrete a hormone that helps the rat's brain assess the amount of body fat present. The brain tries to keep the amount of that hormone (which also appears to act on the brain area that regulates appetite and metabolic rate) at a set level, resulting in the so-called set point—a weight that the body comes back to, even after resolute dieting. The gene that encodes this hormone, called the obese or ob gene, has been isolated in both rats and humans. In addition, a gene that influences obesity and the onset of diabetes has been identified. It has been estimated that from 8 to 30 different genes may influence obesity.

Treatment

Radical treatments for weight loss have included wiring shut the jaw, stapling the stomach, and intestinal bypass operations circumventing a large area of the small intestine, limiting the area where food is absorbed. The "diet pills" of the 1960s, essentially amphetamines such as Dexedrine, are now seldom prescribed for weight loss. Fenfluramine and dexfenfluramine, drugs formerly used to achieve short-term weight loss, were withdrawn from the market following concerns that they could cause heart valve damage. Drugs available by the late 1990s included sibutramine (Meridia), which is an appetite suppressant, and orlistat (Xenical), which acts to block absorption of dietary fat in the intestine. In 2007 an over-the-counter version of orlistat was approved by the Food and Drug Administration.

Although the study of obesity is yielding many possibilities for treatment, the main focus remains diet (especially a diet limiting fat calories) and exercise, often coupled with emotional and behavioral support. The long-term weight-loss success of most attempts at dieting, however, is notoriously low. Groups such as Overeaters Anonymous, modeled after Alcoholics Anonymous Alcoholics Anonymous (AA), worldwide organization dedicated to the treatment of alcoholics; founded 1935 by two alcoholics, one a New York broker, the other an Ohio physician.
..... Click the link for more information. , give support to people with weight problems and eating disorders.

obesity

Excessive body fat. It is usually caused by sedentary habits and a diet high in fat, alcohol, or total calories. Calories consumed but not used are stored as fat. Rare causes include glandular defects and excess steroids (see Cushing syndrome). Obesity raises the risk of heart disease and diabetes mellitus. Treatment, by reducing calorie intake and increasing exercise, is best undertaken with a doctor's advice.

obesity [ō′bē·səd·ē]

(medicine)

An excessive accumulation of body fat which confers health risks such as diabetes, cardiovascular diseases, arthritis, and some types of tumors.