Backgrounder
Rates of overweight and obesity in the United States have grown to epidemic proportions over the last 20 years. In 2005, the Surgeon General estimated that two-thirds of Americans were overweight or obese. The latest data from the NCHS show that 30 percent of U.S. adults 20 years of age and older—more than 60 million people—are obese. The direct costs and indirect costs of overweight and obesity amounted to about $117 billion in 2000. Intangible costs (such as impaired quality of life) have not been estimated, but given the social and psychological consequences of obesity, they are likely to be enormous.
Childhood overweight and obesity rates are especially alarming. According to the National Center for Health Statistics (NCHS) report, Health, United States, 2005, 16 percent of children and adolescents aged six to 19 were overweight. The prevalence of overweight among children and adolescents has doubled and tripled, respectively, over a period of twenty-six years (1976-2002). Research shows that overweight children are more likely to become overweight adults and, therefore, are at greater risk for associated health problems. In fact, 60 percent of overweight five- to 10-year-old children already have at least one risk factor for heart disease.
While all children and adolescents are at risk, those belonging to certain ethnic population groups may be more predisposed to overweight than others. Data from the National Health and Nutrition Examination Survey (NHANES 2003-2004) indicated that the risk of overweight among Mexican-American children and adolescents aged two to 19 is 41 percent: more than five and 10 percentage points higher than their non-Hispanic white (35 percent) and non-Hispanic black (30 percent) contemporaries, respectively.
Global in Scope
Overweight and obesity are not just a U.S. issue; its prevalence is increasing throughout the world’s population. The World Health Organization (WHO) reports that more than one billion adults are overweight and at least 300 million of them are clinically obese. Levels of obesity range from below five percent in China, Japan, and certain African nations to over 75 percent in urban Samoa.
Worldwide, over 22 million children under the age of five are overweight as are 155 million school-age children. In a 2006 review published in the International Journal of Pediatric Obesity, North America, Europe, and parts of the Western Pacific have the highest prevalence of overweight among children (approximately 20 to 30 percent). Furthermore, the levels of obesity among school-age children in countries undergoing economic growth, such as Brazil, Chile, Mexico, and Egypt, are catching up with fully industrialized countries. Based on the current secular trends and the International Obesity Task Force (IOTF) criteria, experts estimate that one in seven children in the Americas will be obese by 2010 as will one in every 10 children in the Eastern Mediterranean and European regions.
WHO considers obesity to be one of the top 10 causes of preventable death worldwide. While malnutrition and unsafe sex account for more deaths, high blood pressure, smoking, high cholesterol, and obesity are impacting both industrialized and developing countries. The 2003 Joint FAO/WHO Expert Consultation on Diet, Nutrition, and the Prevention of Chronic Diseases estimated that non-communicable diseases (NCDs) such as obesity, diabetes, hypertension, stroke, and various forms of cancer accounted for 60 percent of the 55.7 million deaths that occurred in 2000. If unchecked, NCDs are expected to contribute nearly 75 percent of all deaths by the year 2020.
Definitions and Measures of Overweight/Obesity
According to the National Institutes of Health (NIH), overweight refers to an excess of body weight compared to set standards. The excess weight may come from muscle, bone, fat, and/or bodily water. Obesity refers specifically to having an abnormally high proportion of body fat. A person can be overweight without being obese, as in the example of a bodybuilder or other athlete who has a lot of muscle. However, many people who are overweight are also obese.
The Centers for Disease Control and Prevention (CDC), researchers, and health professionals use Body Mass Index (BMI) as the preferred method for determining overweight and obesity in adults, though other methods exist and are in use. BMI is a calculation that divides a person’s weight in kilograms by height in meters squared (BMI = [kg/m2]). BMI can also be calculated in pounds and inches: BMI = [lbs/in2] x 703. The general guideline currently recommended by the CDC is that individuals with a BMI of 25 to 29.9 are considered overweight, and those individuals with a BMI greater than 30 are considered obese. It is important to note that BMI does not use body fat or frame size in its calculations. Therefore, it is possible for an individual with a high proportion of lean body mass (muscle) to have an elevated BMI and not necessarily be at risk for adverse health conditions associated with overweight and obesity. These charts can be found at the CDC Web site: http://www.cdc.gov/nccdphp/dnpa/obesity/defining.htm.
For children, gender-specific BMI charts have been developed. Children with a BMI at or above the 95th percentile represented in these charts are considered overweight. Children in the 85th percentile are considered at risk for overweight. These charts can also be found on the CDC Web site: http://www.cdc.gov/nccdphp/dnpa/bmi/bmi-for-age.htm.
External Resources
- American Obesity Association
- American Society of Bariatric Physicians
- Healthy People 2010: Nutrition and Overweight
- International Obesity Taskforce, International Association for the Study of Obesity (IOTF-IASO)
- Obesity Online, North American Association for the Study of Obesity (NAASO)
- Overweight and Obesity, Centers for Disease Control and Prevention (CDC)
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