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Statistics Related to Overweight and Obesity

Overweight Prevalence
(All figures are for U.S.)

Sixty-one percent of U.S. Adults are overweight or obese. (1999)

Thirty-five percent of U.S. Adults are overweight (BMI of 25.0-29.9). (1999)

Twenty-six percent of U.S. Adults are obese (BMI greater than or equal to 30.0). (1999)

Percent of Adolescents (ages 12-19) Who Are Overweight: 14% (1999)

Percent of Children (ages 6-11) Who Are Overweight: 13% (1999)

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

Initial results from the 1999 National Health and Nutrition Examination Survey (NHANES), using measured heights and weights, indicate that an estimated 61% of U.S. adults are either overweight or obese. This represents a prevalence that is approximately 5% higher than the age-adjusted overweight estimates obtained from NHANES III (1988-94).

Body mass index, 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). 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 NHANES were compared with those of the NHANES III. Both NHANES III and NHANES 1999 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%. However, the NHANES 1999 data for persons age 20 years and over suggest an increase in the proportion of obese adults in the U.S., where the estimated age-adjusted prevalence moved upward from a previous level of 23% to a new level of approximately 26%. Among adults age 20-74 years, the estimated prevalence of overweight (BMI 25.0-29.9) has increased approximately 2% between NHANES II and NHANES 1999, whereas obesity (BMI greater than or equal to 30.0) has nearly doubled from approximately 15% to an estimated 27%.

Because the sample size for NHANES 1999 is smaller than that of the multiyear NHANES III, additional data from subsequent annual NHANES surveys will be necessary to confirm these findings and to allow more detailed analyses of trends in overweight and obesity in all population subgroups. These national data will provide additional information to more fully assess the trends in overweight and obesity, and monitor progress toward achieving the Healthy People 2010 weight status objectives.

Prevalence of Overweight Among Children and Adolescents: United States, 1999

Initial results from the 1999 National Health and Nutrition Examination Survey (NHANES), using measured heights and weights, indicate that an estimated 13 percent of children ages 6-11 years and 14 percent of adolescents ages 12-19 years are overweight. This represents a 2 to 3 percent increase from the overweight estimates of 11 percent obtained from NHANES III (1988-94).

Body mass index, expressed as weight/height2 (BMI;kg/m2) is commonly used to classify overweight and obesity among adults, and is also recommended to identify children who are overweight or at risk of becoming overweight. Cutoff criteria are based on the 2000 CDC BMI-for-age-growth charts for the United States. Based on current recommendations of expert committees, children with BMI values at or above the 95th percentile of the sex-specific BMI growth charts are categorized as overweight.

To assess changes in overweight that have occurred over time, prevalence estimates for participants in the 1999 NHANES were compared with estimates for those who participated in earlier surveys. The NHANES 1999 and earlier surveys used a stratified, multistage, probability sample of the civilian noninstitutionalized U.S. 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 measurements were taken by trained health technicians, using standardized measuring procedures and equipment. Observations for persons missing a valid height or weight measurement were not included in the data analysis.

When the overweight definition (greater than or equal to 95th percentile of the age- and sex-specific BMI) is applied to data from earlier national health examination surveys, it is apparent that overweight in children and adolescents was relatively stable from the 1960's to 1980. However, from NHANES II (1976-80) to NHANES III, the prevalence of overweight nearly doubled among both children and adolescents. In the time interval between NHANES II and III, the prevalence of overweight among children ages 6-11 years increased from an estimated 7 percent to 11 percent, and among adolescents ages 12-19 years, increased from 5 percent to 11 percent. One of the national health objectives for 2010 is to reduce the prevalence of overweight from the NHANES III baseline of 11 percent. However, the NHANES 1999 overweight estimates suggest that since 1994, overweight in youths has not leveled off or decreased, and maybe increasing to even higher levels. The data for adolescents are of notable concern because overweight adolescents are at increased risk to become overweight adults. The 1999 findings for children and adolescents suggest the likelihood of another generation of overweight adults who may be at risk for subsequent overweight and obesity related health conditions.

Because the sample size for NHANES 1999 is smaller than that of the multiyear NHANES III, additional data from further annual NHANES surveys will be necessary to confirm these findings and to allow more detailed analyses of trends in overweight for population subgroups. The ongoing NHANES will provide additional information to more fully assess the trends in overweight and monitor progress toward achieving the Healthy People 2010 weight status objectives.

U.S. DEPARTMENT OF HEALTH AND HUMAN SERVICES
Centers for Disease Control and Prevention
National Center for Health Statistics
Division of Data Services
Hyattsville, MD
20782-2003