Obesity

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 (BMI). 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, hypertension, stroke, and coronary artery disease, 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. 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, operations that reduce the size of 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 to treat obesity now include 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, give support to people with weight problems and eating disorders.

The Columbia Encyclopedia, 6th ed. Copyright© 2014, The Columbia University Press.

Selected full-text books and articles on this topic

The Obesity Epidemic: Science, Morality, and Ideology
Michael Gard; Jan Wright.
Routledge, 2005
Fat Politics: The Real Story behind America's Obesity Epidemic
J. Eric Oliver.
Oxford University Press, 2006
Eating Disorders and Obesity: A Comprehensive Handbook
Christopher G. Fairburn; Kelly D. Brownell.
Guilford Press, 2005 (2nd edition)
The Nature of Nutrition: A Unifying Framework from Animal Adaptation to Human Obesity
Stephen J. Simpson; David Raubenheimer.
Princeton University Press, 2012
Obesity: An Economic and Financial Perspective
Goel, Rajeev K.
Journal of Economics and Finance, Vol. 30, No. 3, Fall 2006
PEER-REVIEWED PERIODICAL
Peer-reviewed publications on Questia are publications containing articles which were subject to evaluation for accuracy and substance by professional peers of the article's author(s).
The Management of Obesity and Related Disorders
Peter G. Kopelman.
Martin Dunitz, 2001
Fat: Fighting the Obesity Epidemic
Robert Pool.
Oxford University Press, 2001
The Overweight Patient: A Psychological Approach to Understanding and Working with Obesity
Kathy Leach.
Jessica Kingsley, 2006
The Fat Studies Reader
Esther Rothblum; Sondra Solovay.
New York University Press, 2009
Fat Rights: Dilemmas of Difference and Personhood
Anna Kirkland.
New York University Press, 2008
Childhood Obesity: Trends and Potential Causes
Anderson, Patricia M.; Butcher, Kristin F.
The Future of Children, Vol. 16, No. 1, Spring 2006
PEER-REVIEWED PERIODICAL
Peer-reviewed publications on Questia are publications containing articles which were subject to evaluation for accuracy and substance by professional peers of the article's author(s).
Obesity in Older Adults
Newman, Ann Mabe.
Online Journal of Issues in Nursing, Vol. 14, No. 1, January 2009
PEER-REVIEWED PERIODICAL
Peer-reviewed publications on Questia are publications containing articles which were subject to evaluation for accuracy and substance by professional peers of the article's author(s).
Scholarly Perspectives on Obesity among Black Women
Johnson, Portia; Wesley, Yvonne.
ABNF Journal, Vol. 23, No. 3, Summer 2012
PEER-REVIEWED PERIODICAL
Peer-reviewed publications on Questia are publications containing articles which were subject to evaluation for accuracy and substance by professional peers of the article's author(s).
Obesity and Alzheimer's Disease
Chang, C. L.
Hong Kong Journal of Psychiatry, Vol. 18, No. 1, March 2008
PEER-REVIEWED PERIODICAL
Peer-reviewed publications on Questia are publications containing articles which were subject to evaluation for accuracy and substance by professional peers of the article's author(s).
Obesity and Cancer: How Understanding the Connection Early Can Have an Impact on Prevention
Bhushan, Alok; Lai, James C. K.
Forum on Public Policy: A Journal of the Oxford Round Table, Spring 2008
PEER-REVIEWED PERIODICAL
Peer-reviewed publications on Questia are publications containing articles which were subject to evaluation for accuracy and substance by professional peers of the article's author(s).
Obesity-Stigma as a Multifaceted Constraint to Leisure
Lewis, Stephen T.; Van Puymbroeck, Marieke.
Journal of Leisure Research, Vol. 40, No. 4, Fall 2008
PEER-REVIEWED PERIODICAL
Peer-reviewed publications on Questia are publications containing articles which were subject to evaluation for accuracy and substance by professional peers of the article's author(s).
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