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Obesity in adults: Prevalence, screening, and evaluation

George A Bray, MD
Leigh Perreault, MD
Section Editor
F Xavier Pi-Sunyer, MD, MPH
Deputy Editor
Daniel J Sullivan, MD, MPH


The morbidity and mortality associated with being overweight (body mass index [BMI] of 25 to 29.9 kg/m2) or obese (BMI of ≥30 kg/m2) have been known to the medical profession for more than 2000 years [1]. Obesity is a chronic disease that is increasing in prevalence in adults, adolescents, and children and is now considered to be a global epidemic. Screening for obesity can identify high-risk patients who may not otherwise receive counseling about health risks, lifestyle changes, obesity treatment options, and risk factor reduction. Evaluation of an overweight or obese patient should include both clinical and laboratory studies; the combined information is used to characterize the type and severity of obesity, determine health risk, and provide a basis for selecting therapy.

The prevalence of obesity, the approach to screening, and the clinical evaluation of obesity in adults will be reviewed here. The health risks associated with obesity and approach to treatment are discussed in detail separately. (See "Obesity in adults: Health consequences" and "Obesity in adults: Overview of management".)


Obesity is a chronic disease that is increasing in prevalence around the world. Estimates of obesity prevalence in the United States using consistent, standardized methods have been ongoing since 1960 [2,3]. Prevalence data have been collected in two ways: annual telephone surveys conducted by state Departments of Health in collaboration with the Centers for Disease Control and Prevention in Atlanta, GA (the Behavioral Risk Factor Surveillance System [BRFSS]) and direct measurement of height and weight in field surveys by the National Center for Health Statistics as the National Health and Nutrition Examination Survey (NHANES).

Data from BRFSS, the telephone survey, reported a prevalence that was approximately two-thirds that of the NHANES surveys. This could be because people underreport their weight, overreport their height, or both during the telephone surveys. Thus, when reading literature on prevalence of overweight and obesity, it is important to identify which survey was used.

United States

Behavioral risk factor (telephone) survey — The prevalence of obesity obtained by self-report in the United States in 2014 was 28.9 percent, ranging from 20.2 percent in Colorado to 36.2 percent in Louisiana [4]. The prevalence was higher in the Midwest and the South and lower in the Northeast and the West. Although there was a dramatic increase in obesity rates between 1990 and 2010, rates appear to be stabilizing. The self-reported prevalence of obesity by region generally parallels the results obtained by more rigorous objective surveys, but the self-reported prevalences are lower [5].

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Literature review current through: Nov 2017. | This topic last updated: Jan 31, 2017.
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