Body composition estimates from NHANES III bioelectrical impedance data.

BACKGROUND: Body composition estimates for the US population are important in order to analyze trends in obesity, sarcopenia and other weight-related health conditions. National body composition estimates have not previously been available. OBJECTIVE: To use transformed bioelectrical impedance analysis (BIA) data in sex-specific, multicomponent model-derived prediction formulae, to estimate total body water (TBW), fat-free mass (FFM), total body fat (TBF), and percentage body fat (%BF) using a nationally representative sample of the US population. DESIGN: Anthropometric and BIA data were from the third National Health and Nutrition Examination Survey (NHANES III; 1988-1994). Sex-specific BIA prediction equations developed for this study were applied to the NHANES data, and mean values for TBW, FFM, TBF and %BF were estimated for selected age, sex and racial-ethnic groups. RESULTS: Among the non-Hispanic white, non-Hispanic black, and Mexican-American participants aged 12-80 y examined in NHANES III, 15 912 had data available for weight, stature and BIA resistance measures. Males had higher mean TBW and FFM than did females, regardless of age or racial-ethnic status. Mean TBW and FFM increased from the adolescent years to mid-adulthood and declined in older adult age groups. Females had higher mean TBF and %BF estimates than males at each age group. Mean TBF also increased with older age groups to approximately 60 y of age after which it decreased. CONCLUSIONS: These mean body composition estimates for TBW, FFM, TBF and %BF based upon NHANES III BIA data provide a descriptive reference for non-Hispanic whites, non-Hispanic blacks and Mexican Americans in the US population.

Association between infant breastfeeding and overweight in young children.

CONTEXT: It has been suggested that breastfeeding is protective against children becoming overweight, and that there is a dose-dependent effect of its duration. OBJECTIVE: To determine whether breastfeeding and its duration are associated with a reduced risk of being overweight among young children in the United States. DESIGN AND SETTING: Data on infant feeding and child overweight status were taken from the third National Health and Nutrition Examination Survey (NHANES III), a cross-sectional health examination survey conducted from 1988-1994. SUBJECTS: Sample of 2685 US-born children between the ages of 3 and 5 years, with birth certificates, height and weight measures, and information on infant feeding. MAIN OUTCOME MEASURES: A body mass index (BMI) between the 85th and 94th percentile was considered at risk of overweight and a BMI in the 95th percentile or higher was considered being overweight. RESULTS: After adjusting for potential confounders, there was a reduced risk of being at risk of overweight for ever breastfed children (adjusted odds ratio [AOR], 0.63; 95% confidence interval [CI], 0.41-0.96) compared with those never breastfed. There was no reduced risk of being overweight (AOR, 0.84; 95% CI, 0.62-1.13). There was no clear dose-dependent effect of the duration of full breastfeeding on being at risk of overweight or overweight and no threshold effect. The strongest predictor of child overweight status was the mother's concurrent weight. The rate of children being overweight nearly tripled with maternal overweight status (BMI, 25.0-29.9 kg/m(2); AOR, 2.95; 95% CI, 1.35-6.42) and more than quadrupled with maternal obesity status (BMI >/=30.0 kg/m(2); AOR, 4.34; 95% CI, 2.50-7.54). CONCLUSIONS: There are inconsistent associations among breastfeeding, its duration, and the risk of being overweight in young children. Breastfeeding continues to be strongly recommended, but may not be as effective as moderating familial factors, such as dietary habits and physical activity, in preventing children from becoming overweight.

Effects of age on validity of self-reported height, weight, and body mass index: findings from the Third National Health and Nutrition Examination Survey, 1988-1994.

OBJECTIVE: To compare self-reported to measured heights and weights of adults examined in the Third National Health and Nutrition Examination Survey (NHANES III), and to determine to what extent body mass index (BMI) calculated from self-reported heights and weights affects estimates of overweight prevalence compared with BMI calculated from measured values. DESIGN: A complex sample design was used in NHANES III to obtain a nationally representative sample of the US civilian, noninstitutionalized population. During household interviews, survey respondents were asked their height and weight. Trained health technicians subsequently measured height and weight using standardized procedures and equipment. SUBJECTS: The analytical sample consisted of 7,772 men and 8,801 women 20 years old and older. STATISTICAL ANALYSES PERFORMED: Only persons with measured and self-reported heights and weights were included in the analysis, and statistical sampling weights were applied. t Tests, Pearson product moment correlation coefficients, sensitivity, and specificity analyses were used to determine the validity of self-reported measurements and prevalence estimates of overweight, defined as BMI of 25 or greater. RESULTS: Age is an important factor in classifying weight, height, BMI, and overweight from self-reports. Statistically significant differences were found for the mean error (measured-self-reported values) for height and BMI that were notably larger for older age groups. For example, the mean error for height ranged from 2.92 to 4.50 cm for women and from 3.06 to 4.29 cm for men, 70 years and older. Despite the high correlation between measured and self-reported data, the prevalence of overweight calculated from measured values was higher than that calculated from self-reported values among older adults. When calculated with self-reported height, BMI was one unit lower than when calculated from measured height for persons > or = 70 years. Specificity was high but sensitivity decreased with increasing age cohorts. Regression equations are provided to determine actual height from self-reported values for older adults. CONCLUSION/APPLICATIONS: Self-reported heights and weights can be used with younger adults, but they have limitations for older adults, ages > or = 60 years. In research studies and in clinical settings involving older adults, failure to measure height and weight can result in subsequent misclassification of overweight status. Therefore, registered dietitians are encouraged to obtained a measured weight and height using a calibrated scale and stadiometer.

Criteria for definition of overweight in transition: background and recommendations for the United States.

Overweight and obesity are leading nutrition-related disorders of clinical and public health concern. Assessment and classification of these conditions are dependent on specific body mass index (BMI; in kg/m(2)) cutoff points. US government agencies are making the transition to a revised BMI definition of overweight from that previously recommended for general use. The purpose of this article is to inform the broader medical and scientific communities of the transition that is underway in the United States to identify and classify overweight among adults by using BMI. Historical background on the use of BMI in a variety of applications, as reported in US federal government agency documents, provides an understanding of previous and current weight-for-height guidelines and the basis for arriving at them. On the basis of the current Dietary Guidelines for Americans, US government agencies are moving toward the use of criteria for overweight and obesity that are consistent with current international standards. Clinicians, researchers, and journal editors should be aware of the transition toward a common definition of healthy weight, overweight, and obesity. To facilitate comparisons and reporting of data, others are encouraged to consider making this transition as well.

Stature, weight, and body mass among young US children born at term with appropriate birth weights.

OBJECTIVE: To describe weight, stature, and body mass index (BMI) changes occurring before the age of 7 years, which may influence the prevalence of overweight in adolescence and adulthood. METHODS: Regression models predicting height and weight at ages 2 months to 6. 75 years were based on the third National Health and Nutrition Examination Survey. Birth certificate data were used to adjust ethnic-specific models for birth weight for gestational age. RESULTS: Attained height is higher for non-Hispanic black children than for either non-Hispanic white or Mexican American children (P 85th percentile than either non-Hispanic white or black children (boys = 25.6%, SE = 2.7 compared with 14.1%, SE = 1.7 and 16.5%, SE = 1.7, respectively; girls = 21.9%, SE = 3.6 compared with 13.0%, SE = 1.7 and 13.7%, SE = 2.2, respectively). For non-Hispanic whites and Mexican Americans and for non-Hispanic black boys, BMI decreased slightly between ages 2 and 6.75 years; BMI for non-Hispanic black girls did not. CONCLUSION: Size differences before the age of 7 years may influence later ethnic-specific overweight prevalence, independent of prenatal influences.

Descriptive anthropometric reference data for older Americans.

OBJECTIVE: To present selected anthropometric data derived from adults aged 60 years and older examined in the third National Health and Nutrition Examination Survey (NHANES III). DESIGN: NHANES III used a complex, stratified, multistage, probability cluster sample design to obtain a nationally representative sample of the US civilian, noninstitutionalized population. Persons aged 60 years and older, Mexican-Americans, and African-Americans were oversampled to produce more reliable estimates for these groups. Trained technicians measured height, weight, skinfold thickness, and circumferences using standardized procedures. SUBJECTS: A total of 5,700 persons aged 60 years and older, and 1,861 persons aged 50 to 59 years. STATISTICAL ANALYSES PERFORMED: Mean and selected percentiles for body weight, body mass index, triceps skinfold thickness, mid upper arm circumference, and arm muscle circumference were calculated by gender, race/ethnicity, and 3 age categories. Weight (lb) per height (in) tables were generated for men and women by age group. RESULTS: Mean body weight was lowest for persons aged 80 years and older. A decline in body mass index occurred that paralleled the direction and magnitude of the progressive decrease observed in weight. Muscle loss with increasing age, as indicated by arm muscle circumference, appeared to be greater among men than women. APPLICATIONS/CONCLUSIONS: In addition to being relatively simple, quick, and inexpensive, anthropometry is the most reliable and specific indicator of malnutrition in the older adult population. The cross-sectional reference data provided can be used by dietitians to interpret anthropometric measurements of persons aged 60 years and older.

CDC growth charts: United States.

OBJECTIVES: This report presents the revised growth charts for the United States. It summarizes the history of the 1977 National Center for Health Statistics (NCHS) growth charts, reasons for the revision, data sources and statistical procedures used, and major features of the revised charts. METHODS: Data from five national health examination surveys collected from 1963 to 1994 and five supplementary data sources were combined to establish an analytic growth chart data set. A variety of statistical procedures were used to produce smoothed percentile curves for infants (from birth to 36 months) and older children (from 2 to 20 years), using a two-stage approach. Initial curve smoothing for selected major percentiles was accomplished with various parametric and nonparametric procedures. In the second stage, a normalization procedure was used to generate z-scores that closely match the smoothed percentile curves. RESULTS: The 14 NCHS growth charts were revised and new body mass index-for-age (BMI-for-age) charts were created for boys and girls (http://www.cdc.gov/growthcharts). The growth percentile curves for infants and children are based primarily on national survey data. Use of national data ensures a smooth transition from the charts for infants to those for older children. These data better represent the racial/ethnic diversity and the size and growth patterns of combined breast- and formula-fed infants in the United States. New features include addition of the 3rd and 97th percentiles for all charts and extension of all charts for children and adolescents to age 20 years. CONCLUSION: Created with improved data and statistical curve smoothing procedures, the United States growth charts represent an enhanced instrument to evaluate the size and growth of infants and children.

Growth and fatness at three to six years of age of children born small- or large-for-gestational age.

OBJECTIVE: To compare young children 3 to 6 years of age who were born small-for-gestational age (SGA; <10th percentile for gestational age) or large-for-gestational age (LGA; >/=90th percentile) with those who were born appropriate-for-gestational age (10th-89th percentile) to determine whether there are differences in growth and fatness in early childhood associated with birth weight status. DESIGN AND METHODS: National sample of 3192 US-born non-Hispanic white, non-Hispanic black, and Mexican-American children 3 to 6 years of age (36-83 months) examined in the third National Health and Nutrition Examination Survey and for whom birth certificates were obtained. On the birth certificates, length of gestation from the mother's last menstrual period was examined for completeness, validity, and whether the pattern of missing (n = 141) and invalid data (n = 147) on gestation was random. Gestation was considered invalid when >44 weeks, or when at gestations of

Growth of infants and young children born small or large for gestational age: findings from the Third National Health and Nutrition Examination Survey.

OBJECTIVES: To compare the growth profiles of infants and young children born small for gestational age (SGA, < 10th percentile birth weight for gestation) or large for gestational age (LGA, > or =90th percentile) with those appropriate for gestational age, and to document the expected growth patterns through early childhood based on national health examination survey data. SAMPLE: Infants and children, 2 to 47 months of age, who were born in the United States and examined using the Third National Health and Nutrition Examination Survey (1988-1994). MAIN OUTCOME MEASURES: Measurements of growth status based on normalized distributions (z scores or standard deviation units [SDUs] for weight, length, and head circumference. RESULTS: Prevalence rates were as follows: SGA infants, 8.6%; appropriate for gestational age infants, 80.9%; and LGA infants, 10.5%. Infants who were SGA appeared to catch up in weight in the first 6 months, but thereafter maintained a deficit of about -0.75 SDUs compared with infants who were appropriate for gestational age. The weight status of LGA infants remained at about +0.50 SDUs through 47 months of age. Length and head circumference were also associated with birth weight status, averaging over -0.60 SDUs for SGA infants and +0.43 SDUs for LGA infants. CONCLUSIONS: Birth weight status is related to growth rates in infancy and early childhood, which underscores the importance of considering child growth relative to birth status when using growth charts. Small for gestational age infants remain shorter and lighter and have smaller head circumferences, while LGA infants grow longer and heavier and have larger head circumferences.

Muscularity and fatness of infants and young children born small- or large-for-gestational-age.

OBJECTIVE: There is growing interest in the extent to which body composition, both short- and long-term, differs in infants and children born at the extremes of birth weight. This is because a growing number of studies have linked low birth weight and fetal growth restriction to the chronic diseases in adulthood that often are obesity-related, and there is also evidence to suggest that heavy infants may be at increased risk for obesity in later life, again with the attendant obesity-related chronic diseases. Our objective was to compare anthropometric indices of body composition of infants and young children born small-for-gestational-age (SGA, <10th percentile) or large-for-gestational age (LGA, >/=90th percentile) with those of normal birth weight status (appropriate-for-gestational-age, AGA) in a US sample. DESIGN: National sample of US-born non-Hispanic white, non-Hispanic black, and Mexican-American infants and young children, 2 to 47 months of age, examined in the third National Health and Nutrition Examination Survey (NHANES III, 1988-1994), for whom birth certificates were obtained. The primary outcomes were normalized anthropometric indices (z scores or standard deviation units [SDU]) of nutritional status and body composition (mid-upper arm circumference, triceps and subscapular skinfolds, mid-upper arm muscle and mid-upper arm fat areas (UFA), and the arm fat index). The outcomes thus were scaled to permit comparison across chronologic ages. RESULTS: The prevalence of SGA was 8.6%, appropriate-for-gestational-age 80.9%, and LGA 10.5%. From ages 2 to 47 months, for infants and young children born SGA, there was a persistent overall deficit in muscularity (mid-upper arm circumference and mid-upper arm muscle area) of approximately -0.50 SDU, but less of a deficit in fatness, particularly at the youngest ages. For infants and young children born LGA, there was a surfeit in muscularity of approximately 0.45 SDU, with less of a surfeit in fatness, particularly at the youngest ages. Across all ages, the mean UFA showed a statistically significant deficit for SGA children (-0.27 +/- 0.10 SDU) and surfeit for LGA children (0.24 +/- 0.08 SDU). At individual ages for UFA and at individual and all ages combined for skinfold thicknesses, there were no significant differences in level of subcutaneous fatness in the three birth-weight-for-gestational-age groups. There was a tendency in the first year for the arm fat index (% arm fat) to be significantly higher for SGA infants, but the effect did not persist after the first year. CONCLUSION: SGA infants remain smaller and LGA infants larger in size through early childhood, but the discrepancies in weight are primarily attributable to differences in lean body mass (muscularity). Fatness is less affected. Thus, based on the fatness indicators used, at any given weight for infants and children 2 to 47 months of age, percent body fat appears to be relatively higher for children who were SGA at birth and lower in those who were LGA at birth. These differences in body composition for SGA infants support the evidence documenting a link between disturbances in intrauterine growth and chronic disease associated with subsequent adiposity in adulthood.

Overweight and obesity in the United States: prevalence and trends, 1960-1994.

OBJECTIVE: To describe the prevalence of, and trends in, overweight and obesity in the US population using standardized international definitions. DESIGN: Successive cross-sectional nationally representative surveys, including the National Health Examination Survey (NHES I; 1960-62) and the National Health and Nutrition Examination Surveys (NHANES I: 1971-1974; NHANES II: 1976-1980; NHANES III: 1988-94). Body mass index (BMI:kg/m2) was calculated from measured weight and height. Overweight and obesity were defined as follows: Overweight (BMI > or = 25.0); pre-obese (BMI 25.0-29.9), class I obesity (BMI 30.0-34.9), class II obesity (BMI 35.0-39.9), and class III obesity (BMI > or = 40.0). RESULTS: For men and women aged 20-74 y, the age-adjusted prevalence of BMI 25.0-29.9 showed little or no increase over time (NHES I: 30.5%, NHANES I: 32.0%, NHANES II: 31.5% and NHANES III: 32.0%) but the prevalence of obesity (BMI > or = 30.0) showed a large increase between NHANES II and NHANES III (NHES I: 12.8%; NHANES I, 14.1%; NHANES II, 14.5% and NHANES III, 22.5%). Trends were generally similar for all age, gender and race-ethnic groups. The crude prevalence of overweight and obesity (BMI >> 25.0) for age > or = 20 y was 59.4% for men, 50.7% for women and 54.9% overall. The prevalence of class III obesity (BMI > or = 40.0) exceeded 10% for non-Hispanic black women aged 40-59 y. CONCLUSIONS: Between 1976-80 and 1988-94, the prevalence of obesity (BMI > or= 30.0) increased markedly in the US. These findings are in agreement with trends seen elsewhere in the world. Use of standardized definitions facilitates international comparisons.

Stature prediction equations for elderly non-Hispanic white, non-Hispanic black, and Mexican-American persons developed from NHANES III data.

OBJECTIVE: To develop new, nationally representative equations to predict stature for racial/ethnic groups of the elderly population in the United States. DESIGN: Anthropometric data for stature, knee height, and sitting height for adults aged 60 years or older were collected from a sample of persons in the third National Health and Nutrition Examination Survey (1988-1994), a national probability sample of the US population. SUBJECTS: A gender- and racial/ethnic-stratified sample of 4,750 persons from the US population (1,369 non-Hispanic white men, 1,472 non-Hispanic white women, 474 non-Hispanic black men, 481 non-Hispanic black women, 497 Mexican-American men, 457 Mexican-American women) aged 60 years or older participated in this study. STATISTICAL ANALYSES: Sampling weights were used to adjust the individual data to account for unequal probabilities of selection, nonresponse, and coverage errors so that all individual data used in these analyses represented national probability estimates. Regression analysis was performed to predict stature in each gender and ethnic group, and the results were cross-validated. RESULTS: Stature prediction models using knee height and age and sitting height and age were evaluated for each gender and racial/ethnic group. The equations with knee height and age were selected on the basis of root mean square error and pure errors in cross-validation and on the accuracy and validity of measures of knee height over sitting height. Results of these regressions, including regression coefficients, standard errors of the coefficients, multiple correlation coefficients, root mean square error, and the standard error for the individual for the final equations, are presented. CONCLUSIONS: New stature prediction equations using knee height and age are presented for non-Hispanic white, non-Hispanic black and Mexican-American elderly persons from current nationally representative data. These equations should be applied when a measure of stature cannot be obtained, for example, for persons with amputations of the leg, or with spinal curvature or who are confined to bed. Predicted stature values are acceptable surrogates in nutritional indexes.

Prevalence of overweight among preschool children in the United States, 1971 through 1994.

OBJECTIVE: To examine the prevalence of overweight among US preschool children 2 months through 5 years of age between the years 1971 through 1974 and 1988 through 1994. DESIGN: Nationally representative cross-sectional surveys with a physical examination, including measurement of stature, length, and weight. Between 1200 and 7500 children younger than 6 years were examined in each of four different surveys during 1971 through 1974 (first National Health and Nutrition Examination Survey [NHANES I]), 1976 through 1980 (NHANES II), 1982 through 1984 (Hispanic Health and Nutrition Examination Survey), and 1988 through 1994 (NHANES III). RESULTS: The prevalence of overweight increased among some sex and age groups of preschool children between 1971 through 1974 and 1988 through 1994. More than 10% of 4- and 5-year-old girls were overweight in 1988 through 1994 compared with 5.8% in 1971 through 1974. However, there was no change during this period in the prevalence of overweight among 1- and 2- to 3-year-old children. During 1988 through 1994, the prevalence of overweight among children 2 months through 5 years of age was consistently higher in girls than boys. Mexican-American children had a higher prevalence of overweight than non-Hispanic black and non-Hispanic white children. These results parallel what has been reported for older children and adults in the United States. CONCLUSION: These results show that in the last 20 years the prevalence of overweight has increased among 4- and 5-year-old children but not among younger children. These findings suggest that efforts to prevent overweight, including encouragement of physical activity and improved diets, should begin in early childhood.

Varying body mass index cutoff points to describe overweight prevalence among U.S. adults: NHANES III (1988 to 1994).

Body mass index (BMI; kg/m2) distributions are commonly reported in the scientific literature to describe weight for stature. These data are collected for various groups of subjects in local health and body composition studies, and comparisons with national distributions are often desirable. Tabular data for population prevalence estimates from the third National Health and Nutrition Examination Survey (NHANES III, 1988 to 1994) at selected gender- and age-specific BMI levels ranging from < 18.0 to > 45.0 are presented and compared with various examples of BMI criteria reported in the scientific literature. NHANES III was a statistically representative national probability sample of the civilian, noninstitutionalized population of the United States in which height and weight were measured as part of a more comprehensive health examination. The implications of varying population prevalence estimates based on varying BMI cutoff points are briefly discussed for selected examples including World Health Organization over-weight/obesity criteria and the U.S. Dietary Guidelines for Americans. The median BMI for U.S. adults aged 20 years and older is 25.5 kg/m2. Median stature and weight for men are 175.5 cm and 80.0 kg and for women are 161.6 cm and 65.6 kg, respectively. The percentage of the population with BMI < 19.0 is 1.6% for men, 5.7% for women; BMI > or = 19.0 to < 25.0 is 39.0% for men, 43.6% for women; BMI > or = 25.0 is 59.4% for men, 50.7% for women. An estimated 97.1 million adults have a BMI > or = 25.0. Additional prevalence estimates based on other BMI cutoff points and ages are presented.

Bioelectrical impedance analysis measurements as part of a national nutrition survey.

Since 1960 the National Center for Health Statistics has conducted seven national health examination surveys. All surveys included anthropometry. As the relations between various chronic diseases and body composition have been recognized, there has been considerable interest in assessing body composition in health examinations on the basis of nationally representative probability samples. I focus on considerations that influenced the decision to include bioelectrical impedance analysis (BIA) in a national nutrition survey. Tetrapolar, single-frequency (50 kHz) BIA was included in the third National Health and Nutrition Examination Survey (1988-1994) for persons aged > or = 12 y, resulting in > 17000 resistance and reactance measures in non-Hispanic white, non-Hispanic black, and Mexican American subjects. The usefulness of these data in producing national reference distributions for lean body mass and fat mass, however, is currently limited by the uncertain availability of generalizable, valid, reliable, cross-validated prediction equations for various age, sex, and racial-ethnic groups.

The influence of smoking cessation on the prevalence of overweight in the United States.

BACKGROUND: The proportion of U.S. adults 35 to 74 years of age who were overweight increased by 9.6 percent for men and 8.0 percent for women between 1978 and 1990. Since the prevalence of smoking declined over the same period, smoking cessation has been suggested as a factor contributing to the increasing prevalence of overweight. METHODS: To estimate the influence of smoking cessation on the increase in the prevalence of overweight, we analyzed data on current and past weight and smoking status for a national sample of 5247 adults 35 years of age or older who participated in the third National Health and Nutrition Examination Survey, conducted from 1988 through 1991. The results were adjusted for age, sociodemographic characteristics, level of physical activity, alcohol consumption, and (for women) parity. RESULTS: The weight gain over a 10-year period that was associated with the cessation of smoking (i.e., the gain among smokers who quit that was in excess of the gain among continuing smokers) was 4.4 kg for men and 5.0 kg for women. Smokers who had quit within the past 10 years were significantly more likely than respondents who had never smoked to become overweight (odds ratios, 2.4 for men and 2.0 for women). For men, about a quarter (2.3 of 9.6 percentage points) and for women, about a sixth (1.3 of 8.0 percentage points) of the increase in the prevalence of overweight could be attributed to smoking cessation within the past 10 years. CONCLUSIONS: Although its health benefits are undeniable, smoking cessation may nevertheless be associated with a small increase in the prevalence of overweight.

Overweight prevalence and trends for children and adolescents. The National Health and Nutrition Examination Surveys, 1963 to 1991.

OBJECTIVE: To examine prevalence of overweight and trends in overweight for children and adolescents in the US population. DESIGN: Nationally representative cross-sectional surveys with an in-person interview and a medical examination, including measurement of height and weight. PARTICIPANTS: Between 3000 and 14,000 youths aged 6 through 17 years examined in each of five separate national surveys during 1963 to 1965, 1966 to 1970, 1971 to 1974, 1976 to 1980, and 1988 to 1991 (Cycles II and III of the National Health Examination Survey, and the first, second, and third National Health and Nutrition Examination Surveys, respectively). MAIN OUTCOME MEASURES: Prevalence of overweight based on body mass index and 85th or 95th percentile cutoff points from Cycles II and III of the National Health Examination Survey. RESULTS: From 1988 to 1991, the prevalence of overweight was 10.9% based on the 95th percentile and 22% based on the 85th percentile. Overweight prevalence increased during the period examined among all sex and age groups. The increase was greatest since 1976 to 1980, similar to findings previously reported for adults in the United States. CONCLUSIONS: Increasing overweight among youths implies a need to focus on primary prevention. Attempts to increase physical activity may provide a means to address this important public health problem.

Increasing prevalence of overweight among US adults. The National Health and Nutrition Examination Surveys, 1960 to 1991.

OBJECTIVE: To examine trends in overweight prevalence and body mass index of the US adult population. DESIGN: Nationally representative cross-sectional surveys with an in-person interview and a medical examination, including measurement of height and weight. SETTING/PARTICIPANTS: Between 6000 and 13,000 adults aged 20 through 74 years examined in each of four separate national surveys during 1960 to 1962 (the first National Health Examination Survey [NHES I]), 1971 to 1974 (the first National Health and Nutrition Examination Survey [NHANES I]), 1976 to 1980 (NHANES II), and 1988 to 1991 (NHANES III phase 1). RESULTS: In the period 1988 to 1991, 33.4% of US adults 20 years of age or older were estimated to be overweight. Comparisons of the 1988 to 1991 overweight prevalence estimates with data from earlier surveys indicate dramatic increases in all race/sex groups. Overweight prevalence increased 8% between the 1976 to 1980 and 1988 to 1991 surveys. During this period, for adult men and women aged 20 through 74 years, mean body mass index increased from 25.3 to 26.3; mean body weight increased 3.6 kg. CONCLUSIONS: These nationally representative data document a substantial increase in overweight among US adults and support the findings of other investigations that show notable increases in overweight during the past decade. These observations suggest that the Healthy People 2000 objective of reducing the prevalence of overweight US adults to no more than 20% may not be met by the year 2000. Understanding the reasons underlying the increase in the prevalence of overweight in the United States and elucidating the potential consequences in terms of morbidity and mortality present a challenge to our understanding of the etiology, treatment, and prevention of overweight.