Prevalence of Overweight and Obesity Among Adults:
United States, 1999-2000

Results from the 1999-2000 National Health and Nutrition Examination Survey (NHANES), using measured heights and weights, indicate that an estimated 64 percent of U.S. adults are either overweight or obese. As shown in table 1, this represents a prevalence that is approximately 8 percent higher than the age-adjusted overweight estimates obtained from NHANES III (1988-94).

Body mass index (BMI), expressed as weight/height² (BMI; kg/m²), is commonly used to classify overweight (BMI 25.0-29.9) and obesity (BMI greater than or equal to 30.0) among adults (age 20 years and over). When age-adjusted prevalence estimates from the NHANES III for adults age 20-74 years were compared with prevalence estimates from NHANES II (1976-80), there were notable increases in the prevalence of persons who were either overweight or obese (BMI greater than or equal to 25.0), as shown in table 2. Most of this increase was attributable to increases in the obese category (BMI greater than or equal to 30.0), whereas only minor increases occurred in the prevalence of persons who are overweight but not obese (BMI 25.0-29.9).

To assess changes in overweight and obesity that have occurred since the 1988-94 time period, prevalence estimates for adults age 20 years and over who participated in the 1999-2000 NHANES were compared with those of the NHANES III. NHANES III and NHANES 1999-2000 used a stratified, multistage, probability sample of the civilian, U.S. noninstitutionalized population. A household interview and a physical examination were conducted for each survey participant. During the physical examination, conducted in mobile examination centers, height and weight were measured as part of a more comprehensive set of body measurements. These measures were taken by trained health technicians, using standardized measuring procedures and equipment. Observations for pregnant women and for persons missing a valid height or weight measurement were not included in the data analysis.

One of the national health objectives for 2010 is to reduce the prevalence of obesity among adults to less than 15 percent. However, the NHANES 1999-2000 data for persons age 20 years and over suggest an increase in the proportion of obese adults in the United States, where the estimated age-adjusted prevalence moved upward from a previous level of 23 percent to a new level of approximately 30 percent. Among adults age 20-74 years, the estimated prevalence of obesity (BMI greater than or equal to 30.0) has doubled between NHANES II and NHANES 1999-2000, from approximately 15 percent to an estimated 31 percent.

Table 1. Age-adjusted* prevalence of overweight and obesity among U.S. adults among U.S. adults, age 20 years and over

*Age-adjusted by the direct method to the year 2000 U.S. Bureau of the Census estimates using the age groups 20-39, 40-59, and 60 years and over.

Table 2. Age-adjusted* prevalence of overweight and obesity among U.S. adults, age 20-74 years

*Age-adjusted by the direct method to the year 2000 U.S. Bureau of the Census estimates using the age groups 20-39, 40-59, and 60-74 years.