The Epidemiology of Obesity
2007; Elsevier BV; Volume: 132; Issue: 6 Linguagem: Inglês
10.1053/j.gastro.2007.03.052
ISSN1528-0012
AutoresCynthia L. Ogden, Susan Z. Yanovski, Margaret D. Carroll, Katherine M. Flegal,
Tópico(s)Diet, Metabolism, and Disease
ResumoIn the United States, obesity among adults and overweight among children and adolescents have increased markedly since 1980. Among adults, obesity is defined as a body mass index of 30 or greater. Among children and adolescents, overweight is defined as a body mass index for age at or above the 95th percentile of a specified reference population. In 2003–2004, 32.9% of adults 20–74 years old were obese and more than 17% of teenagers (age, 12–19 y) were overweight. Obesity varies by age and sex, and by race-ethnic group among adult women. A higher body weight is associated with an increased incidence of a number of conditions, including diabetes mellitus, cardiovascular disease, and nonalcoholic fatty liver disease, and with an increased risk of disability. Obesity is associated with a modestly increased risk of all-cause mortality. However, the net effect of overweight and obesity on morbidity and mortality is difficult to quantify. It is likely that a gene-environment interaction, in which genetically susceptible individuals respond to an environment with increased availability of palatable energy-dense foods and reduced opportunities for energy expenditure, contributes to the current high prevalence of obesity. Evidence suggests that even without reaching an ideal weight, a moderate amount of weight loss can be beneficial in terms of reducing levels of some risk factors, such as blood pressure. Many studies of dietary and behavioral treatments, however, have shown that maintenance of weight loss is difficult. The social and economic costs of obesity and of attempts to prevent or to treat obesity are high. In the United States, obesity among adults and overweight among children and adolescents have increased markedly since 1980. Among adults, obesity is defined as a body mass index of 30 or greater. Among children and adolescents, overweight is defined as a body mass index for age at or above the 95th percentile of a specified reference population. In 2003–2004, 32.9% of adults 20–74 years old were obese and more than 17% of teenagers (age, 12–19 y) were overweight. Obesity varies by age and sex, and by race-ethnic group among adult women. A higher body weight is associated with an increased incidence of a number of conditions, including diabetes mellitus, cardiovascular disease, and nonalcoholic fatty liver disease, and with an increased risk of disability. Obesity is associated with a modestly increased risk of all-cause mortality. However, the net effect of overweight and obesity on morbidity and mortality is difficult to quantify. It is likely that a gene-environment interaction, in which genetically susceptible individuals respond to an environment with increased availability of palatable energy-dense foods and reduced opportunities for energy expenditure, contributes to the current high prevalence of obesity. Evidence suggests that even without reaching an ideal weight, a moderate amount of weight loss can be beneficial in terms of reducing levels of some risk factors, such as blood pressure. Many studies of dietary and behavioral treatments, however, have shown that maintenance of weight loss is difficult. The social and economic costs of obesity and of attempts to prevent or to treat obesity are high. Definitions and Measurement of Overweight and ObesityThe human body contains essential lipids and also nonessential lipids in the form of triglycerides (triacylglycerols) stored in adipose tissue cells known as adipocytes. Obesity generally is defined as excess body fat. The definition of excess, however, is not clear-cut. Adiposity is a continuous trait not marked by a clear division into normal and abnormal. Moreover, it is difficult to measure body fat directly. Consequently, obesity often is defined as excess body weight rather than as excess fat. In epidemiologic studies, body mass index (BMI) calculated as weight in kilograms divided by height in meters squared is used to express weight adjusted for height.8Dietz W.H. Robinson T.N. Use of the body mass index (BMI) as a measure of overweight in children and adolescents.J Pediatr. 1998; 132: 191-193Abstract Full Text Full Text PDF PubMed Scopus (353) Google Scholar, 9Keys A. Fidanza F. Karvonen M.J. Kimura N. Taylor H.L. Indices of relative weight and obesity.J Chronic Dis. 1972; 25: 329-343Abstract Full Text PDF PubMed Google ScholarMeasured weight and height are more accurate than self-reported data. Cost considerations, however, often lead to surveys and epidemiologic studies not being conducted in person, so that height and weight are self-reported rather than measured. Inaccurate estimates may result because respondents tend to overestimate their height and underestimate their weight. Overestimation of height increases with age and is greater among men than women. Underestimation of weight is greater among women than among men.10Kuczmarski M.F. Kuczmarski R.J. Najjar M. 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.J Am Diet Assoc. 2001; 101: 28-34Abstract Full Text Full Text PDF PubMed Google Scholar, 11Niedhammer I. Bugel I. Bonenfant S. Goldberg M. Leclerc A. Validity of self-reported weight and height in the French GAZEL cohort.Int J Obes. 2000; 24: 1111-1118Crossref Google Scholar, 12Flood V. Webb K. Lazarus R. Pang G. Use of self-report to monitor overweight and obesity in populations: some issues for consideration.Aust N Z J Public Health. 1999; 24: 96-99Crossref Google Scholar, 13Nieto-Garcia F.J. Bush T.L. Keyl P.M. Body mass definitions of obesity: sensitivity and specificity using self-reported weight and height.Epidemiology. 1990; 1: 146-152Crossref PubMed Google Scholar, 14Rowland M. Self-reported weight and height.Am J Clin Nutr. 1990; 52: 1125-1133PubMed Google Scholar, 15Perry G.S. Byers T.E. Mokdad A.H. Serdula M.K. Williamson D.F. The validity of self-reports of past body weights by U.S. adults.Epidemiology. 1995; 6: 61-66Crossref PubMed Google ScholarDefinitions for AdultsThere have been many definitions of overweight and obesity for adults. In 1959 and in 1983 the Metropolitan Life Insurance Company produced tables based on the mortality experience of policy holders that indicated the range of weights by height and frame size at which the mortality rate was lowest for policy holders aged 25–59 years.16Metropolitan Life Insurance Company1983 Metropolitan height and weight tables.Stat Bull Metrop Insur Co. 1983; 64: 2Google Scholar, 17Metropolitan Life Insurance CompanyNew weight standards for men and women.Stat Bull Metrop Insur Co. 1959; 40: 1Google Scholar In the past, overweight often was defined as a body weight that was 20% or more above the midpoint of the weight range for a medium frame size from these Metropolitan Life tables.18Burton B.T. Foster W.R. Health implications of obesity: an NIH consensus development conference.J Am Diet Assoc. 1985; 85: 1117-1121PubMed Google ScholarA variety of definitions using BMI, rather than weight-for-height tables, also have been used. Grades I, II, and III obesity, defined by BMI categories of 30–39.9 and 40 or above, for both men and women, were proposed by Garrow19Garrow J.S. Treat obesity seriously: a clinical manual. Churchill Livingstone, Edinburgh1981Google Scholar in 1981. The value of 25 was approximately equivalent to the upper end of the weight range for large frame sizes in the 1959 Metropolitan Life tables. Bray20Bray G.A. Complications of obesity.Ann Intern Med. 1985; 103: 1052-1062Crossref PubMed Google Scholar and a more recent (1995) World Health Organization (WHO)21World Health OrganizationPhysical status: the use and interpretation of anthropometry. WHO, Geneva, Switzerland1995Google Scholar expert committee also used similar BMI classifications. In 1985, an expert committee of the Food and Agriculture Organization of the United Nations/WHO/United Nations University22World Health OrganizationEnergy and protein requirements. World Health Organization, Geneva1985Google Scholar defined obesity as a BMI of 30 or more for men and of 28.6 or more for women. Also in 1985, a US National Institutes of Health Consensus Conference18Burton B.T. Foster W.R. Health implications of obesity: an NIH consensus development conference.J Am Diet Assoc. 1985; 85: 1117-1121PubMed Google Scholar supported a definition of overweight as a BMI of 27.8 or higher for men and of 27.3 or higher for women based on the US population distributions because these values corresponded to approximately 120% of the midpoint of the 1983 Metropolitan Life table ranges. A classification similar to the one proposed by Garrow,19Garrow J.S. Treat obesity seriously: a clinical manual. Churchill Livingstone, Edinburgh1981Google Scholar using different terminology and with an additional cut-off point of a BMI of 35, was accepted as part of the 1997 WHO consultation on obesity.23World Health OrganizationThe global epidemic of obesity. WHO, Geneva1997Google Scholar The WHO classification defined overweight as a BMI of 25 or greater and obesity as a BMI of 30 or greater, along with some additional subdivisions. Similar definitions were recommended by a National Heart, Lung, and Blood Institute (NHLBI) expert committee in the NHLBI Clinical Guidelines on the Identification, Evaluation, and Treatment of Overweight and Obesity in Adults.5National Institutes of HealthClinical guidelines on the identification, evaluation, and treatment of overweight and obesity in adults—the evidence report.Obes Res. 1998; ([erratum in Obes Res 1998;6:464]) (Also available at http://www.nhlbi.gov/guidelines.obesity/ob_gdlns.htm. Accessed October 30, 2006): 51S-209SPubMed Google Scholar Currently, healthy weight is defined as a BMI of 18.5 up to 24.9, overweight as a BMI of 25 up to 29.9, and obesity as a BMI of 30 or greater by the US Dietary Guidelines.24U.S. Department of Health and Human Services and U.S. Department of AgricultureDietary guidelines for Americans. 6th ed. U.S. Government Printing Office, Washington, DC2005Google ScholarThe interpretation of BMI in terms of body fatness and in comparison with a weight standard varies by sex, age, and other factors.25Baumgartner R.N. Heymsfield S.B. Roche A.F. Human body composition and the epidemiology of chronic disease.Obes Res. 1995; 3: 73-95Crossref PubMed Google Scholar In part because of lower muscle and bone mass, women are characterized by a higher percentage of body fat than men. Women tend to have a higher proportion of body fat stored in subcutaneous rather than visceral adipose tissue.26Lemieux S. Prud’homme D. Bouchard C. Tremblay A. Despres J.P. Sex differences in the relation of visceral adipose tissue accumulation to total body fatness.Am J Clin Nutr. 1993; 58: 463-467PubMed Google Scholar Because of the differences in body composition between men and women, at the same BMI women will tend to have a considerably higher percentage of body fat than men. Older persons will tend to have a higher percentage of body fat than younger people at the same BMI because of the changes in body composition with age. Moreover, only if the same body weight standards (or definitions of obesity) are considered to be appropriate for both men and women does a given value of BMI have the same meaning in terms of relative weight. A given value of BMI may be numerically the same for men and women and for people of different ages, but may not represent the same percentage of body fat, the same degree of risk, or even necessarily the same degree of overweight relative to a weight standard.Definitions of Weight Levels for Children and AdolescentsIn children, the terminology for different levels of weight or BMI varies considerably.27Flegal K.M. Tabak C.J. Ogden C.L. Overweight in children: definitions and interpretation.Health Educ Res. 2006; 21: 755-760Crossref PubMed Scopus (60) Google ScholarOverweight, obesity, and at risk for overweight can be found in the literature. Even when the same term is used (eg, overweight) the meaning of that term may not be the same in different countries or across studies. Whatever the terminology used, definitions generally are based on weight and not on adiposity per se. For adults, the currently used definitions of overweight and obesity are related to functional outcomes of mortality and morbidity and are based on fixed values of BMI that do not vary by age or sex.5National Institutes of HealthClinical guidelines on the identification, evaluation, and treatment of overweight and obesity in adults—the evidence report.Obes Res. 1998; ([erratum in Obes Res 1998;6:464]) (Also available at http://www.nhlbi.gov/guidelines.obesity/ob_gdlns.htm. Accessed October 30, 2006): 51S-209SPubMed Google Scholar In children, it is unclear what risk-related criteria to use, so there are no risk-based fixed values of BMI used to determine overweight. As a result, a statistical definition of overweight based on the 85th and 95th percentiles of sex-specific BMI-for-age in a specified reference population often is used in childhood.28Barlow S.E. Dietz W.H. Obesity evaluation and treatment: expert committee recommendations The Maternal and Child Health Bureau, Health Resources and Services Administration and the Department of Health and Human Services.Pediatrics. 1998; 102: E29Crossref PubMed Google Scholar, 29Himes J.H. Dietz W.H. Guidelines for overweight in adolescent preventive services: recommendations from an expert committee The Expert Committee on Clinical Guidelines for Overweight in Adolescent Preventive Services.Am J Clin Nutr. 1994; 59: 307-316PubMed Google ScholarMany reference data sets for childhood BMI exist and BMI reference data are used or recommended as part of monitoring children’s growth in many countries.30Cole T.J. Freeman J.V. Preece M.A. British 1990 growth reference centiles for weight, height, body mass index and head circumference fitted by maximum penalized likelihood.Stat Med. 1998; 17: 407-429Crossref PubMed Scopus (453) Google Scholar, 31Kuczmarski R.J. Ogden C.L. Guo S.S. Grummer-Strawn L.M. Flegal K.M. Mei Z. Wei R. Curtin L.R. Roche A.F. Johnson C.L. 2000 CDC growth charts for the United States: methods and development.Vital Health Stat 11. 2002; 246: 1-190PubMed Google Scholar, 32Cacciari E. Milani S. Balsamo A. Dammacco F. De Luca F. Chiarelli F. Pasquino A.M. Tonini G. Vanelli M. Italian cross-sectional growth charts for height, weight and BMI (6-20 y).Eur J Clin Nutr. 2002; 56: 171-180Crossref PubMed Google Scholar, 33Mast M. Langnase K. Labitzke K. Bruse U. Preuss U. Muller M.J. Use of BMI as a measure of overweight and obesity in a field study on 5-7 year old children.Eur J Nutr. 2002; 41: 61-67Crossref PubMed Scopus (25) Google Scholar, 34Rolland-Cachera M.F. Cole T.J. Sempe M. Tichet J. Rossignol C. Charraud A. Body mass index variations: centiles from birth to 87 years.Eur J Clin Nutr. 1991; 45: 13-21PubMed Google Scholar, 35Cole T.J. Roede M.J. Centiles of body mass index for Dutch children aged 0-20 years in 1980—a baseline to assess recent trends in obesity.Ann Hum Biol. 1999; 26: 303-308Crossref PubMed Google Scholar Reference data usually are based on representative data from a given country. For example, surveys representative of England, Scotland, and Wales were used to develop the 1990 British growth references for weight, height, BMI, and head circumference.30Cole T.J. Freeman J.V. Preece M.A. British 1990 growth reference centiles for weight, height, body mass index and head circumference fitted by maximum penalized likelihood.Stat Med. 1998; 17: 407-429Crossref PubMed Scopus (453) Google Scholar In the United States, the Centers for Disease Control and Prevention (CDC) 2000 growth charts were developed from 5 nationally representative surveys (the National Health Examination Surveys II and III in the 1960s, the National Health and Nutrition Examination Survey [NHANES] I and II in the 1970s, and NHANES III, 1988–1994). The 2000 CDC charts are revised versions of the 1977 National Center for Health Statistics growth charts. They include sex-specific BMI-for-age growth curves for ages 2–19 years by single month of age.31Kuczmarski R.J. Ogden C.L. Guo S.S. Grummer-Strawn L.M. Flegal K.M. Mei Z. Wei R. Curtin L.R. Roche A.F. Johnson C.L. 2000 CDC growth charts for the United States: methods and development.Vital Health Stat 11. 2002; 246: 1-190PubMed Google Scholar Because of the observed increase in weight among children in 1988–1994,36Troiano R.P. Flegal K.M. Kuczmarski R.J. Campbell S.M. Johnson C.L. Overweight prevalence and trends for children and adolescents The National Health and Nutrition Examination Surveys, 1963 to 1991.Arch Pediatr Adolesc Med. 1995; 149: 1085-1091Crossref PubMed Google Scholar all weight data from children ages 6 and older in 1988–1994 were excluded from the 2000 CDC charts. In April 2006, the WHO released BMI-for-age growth charts for preschool-age children from birth to 5 years of age.37World Health OrganizationMethods and development.WHO child growth standards. WHO, Geneva2006Google Scholar The WHO charts are based on a different approach. They were created from healthy, breast-fed children from around the world and are intended to present a standard of physiologic growth and not a descriptive reference. The WHO has used cut-off values based on SD scores (z-scores), with overweight defined as a BMI-for-age value greater than or equal to a z-score of +2.38de Onis M. Blossner M. The World Health Organization global database on child growth and malnutrition: methodology and applications.Int J Epidemiol. 2003; 32: 518-526Crossref PubMed Scopus (125) Google ScholarReferences such as the 1990 UK reference, the 2000 CDC Growth Charts, and the WHO standards are intended for clinical use in monitoring children’s growth. The use of selected percentiles or z-scores on these charts to define overweight or obesity is a secondary purpose.27Flegal K.M. Tabak C.J. Ogden C.L. Overweight in children: definitions and interpretation.Health Educ Res. 2006; 21: 755-760Crossref PubMed Scopus (60) Google ScholarThere are also several sets of BMI reference data that are intended specifically to define childhood overweight and are not for clinical monitoring of growth patterns. One widely used reference set of BMI values consists of sex-specific smoothed 85th and 95th percentiles for single year of age from 6 to 19 years of age based on data from NHANES I, 1971–1974, in the United States.39Must A. Dallal G.E. Dietz W.H. Reference data for obesity: 85th and 95th percentiles of body mass index (wt/ht2) and triceps skinfold thickness.Am J Clin Nutr. 1991; 53 ([erratum in Am J Clin Nutr 1991;54:773]): 839-846PubMed Google Scholar In 1995, a WHO expert committee recommended the use of these reference values.21World Health OrganizationPhysical status: the use and interpretation of anthropometry. WHO, Geneva, Switzerland1995Google ScholarIn 2000, Cole et al40Cole T.J. Bellizzi M.C. Flegal K.M. Dietz W.C. Establishing a standard definition for child overweight and obesity worldwide: international survey.BMJ. 2000; 320: 1240-1243Crossref PubMed Google Scholar published smoothed sex-specific BMI cut-off values based on 6 nationally representative data sets from Brazil, Great Britain, Hong Kong, the Netherlands, Singapore, and the United States. The US data were the same as those from which the 2000 CDC growth charts were derived. These values, often referred to as the International Obesity Task Force cut-off values, represent cut-off points chosen as the percentiles that matched the adult cut-off values of a BMI of 25 and 30 at age 18 years. The International Obesity Task Force cut-off values were not intended as clinical definitions and were not intended to replace national reference data, but rather they were developed to provide a common set of definitions that researchers and policy makers in different countries could use for descriptive and comparative purposes internationally. Discussions on the use of national vs international reference data have been published.41Reilly J.J. Assessment of childhood obesity: national reference data or international approach?.Obes Res. 2002; 10: 838-840Crossref PubMed Google Scholar, 42Chinn S. Rona R.J. Prevalence and trends in overweight and obesity in three cross sectional studies of British children, 1974-94.BMJ. 2001; 322: 24-26Crossref PubMed Google Scholar, 43Fu W.P. Lee H.C. Ng C.J. Tay Y.K. Kau C.Y. Seow C.J. Siak J.K. Hong C.Y. Screening for childhood obesity: international vs population-specific definitions Which is more appropriate?.Int J Obes Relat Metab Disord. 2003; 27: 1121-1126Crossref PubMed Scopus (48) Google ScholarThus, there are a plethora of different references that can be used to define childhood overweight or obesity for calculating prevalence estimates. There are also many articles that compare the use of different definitions with the same population.44Kain J. Uauy R. Vio F. Albala C. Trends in overweight and obesity prevalence in Chilean children: comparison of three definitions.Eur J Clin Nutr. 2002; 56: 200-204Crossref PubMed Google Scholar, 45Flegal K.M. Ogden C.L. Wei R. Kuczmarski R.L. Johnson C.L. Prevalence of overweight in US children: comparison of US growth charts from the Centers for Disease Control and Prevention with other reference values for body mass index.Am J Clin Nutr. 2001; 73: 1086-1093PubMed Google Scholar, 46Wang Y. Wang J.Q. A comparison of international references for the assessment of child and adolescent overweight and obesity in different populations.Eur J Clin Nutr. 2002; 56: 973-982Crossref PubMed Scopus (95) Google Scholar, 47Al-Sendi A.M. Shetty P. Musaiger A.O. Prevalence of overweight and obesity among Bahraini adolescents: a comparison between three different sets of criteria.Eur J Clin Nutr. 2003; 57: 471-474Crossref PubMed Scopus (48) Google Scholar, 48Valerio G. Scalfi L. De Martino C. Franzese A. Tenore A. Contaldo F. Comparison between different methods to assess the prevalence of obesity in a sample of Italian children.J Pediatr Endocrinol Metab. 2003; 16: 211-216PubMed Google Scholar, 49Committee on Scientific Evaluation of WIC Nutrition Risk Criteria Food and Nutrition BoardInstitute of MedicineNational Academy of SciencesSummary of WIC nutrition risk criteria: a scientific assessment.J Am Diet Assoc. 1996; 96: 925-930Abstract Full Text Full Text PDF PubMed Google Scholar As seen repeatedly, the various definitions do not give the same results. Each reference was created using slightly different data and is based on different assumptions.The choice of cut-off points within the reference population depends on what assumptions are made. Expert committees in the United States have recommended using a BMI-for-age at or above the 95th percentile of a specified reference population to screen for overweight in adolescents and younger children.28Barlow S.E. Dietz W.H. Obesity evaluation and treatment: expert committee recommendations The Maternal and Child Health Bureau, Health Resources and Services Administration and the Department of Health and Human Services.Pediatrics. 1998; 102: E29Crossref PubMed Google Scholar, 29Himes J.H. Dietz W.H. Guidelines for overweight in adolescent preventive services: recommendations from an expert committee The Expert Committee on Clinical Guidelines for Overweight in Adolescent Preventive Services.Am J Clin Nutr. 1994; 59: 307-316PubMed Google Scholar These values were not designed to provide clinical cut-off points, but rather to serve as screening values. The same expert committees considered that children with BMI values between the 85th and 95th percentiles also possibly might be overweight, although with a lower probability and are considered at risk for overweight. Thus, for these children, it was recommended that they be referred to a second-level screen, including consideration of family history, blood pressure, total cholesterol, large prior increase in BMI, and concern about weight. These children would be referred for the in-depth evaluation only if they were positive for any of the items on the second-level screen. The category of at risk for overweight is sometimes interpreted as a designation for a child who is at risk for becoming overweight in the future. However, this is not the original intention of the term. The category as defined by the expert committees28Barlow S.E. Dietz W.H. Obesity evaluation and treatment: expert committee recommendations The Maternal and Child Health Bureau, Health Resources and Services Administration and the Department of Health and Human Services.Pediatrics. 1998; 102: E29Crossref PubMed Google Scholar, 29Himes J.H. Dietz W.H. Guidelines for overweight in adolescent preventive services: recommendations from an expert committee The Expert Committee on Clinical Guidelines for Overweight in Adolescent Preventive Services.Am J Clin Nutr. 1994; 59: 307-316PubMed Google Scholar was intended to identify children who might be obese, in the sense of excess body fat, but who should undergo a second-level screen (as described earlier) to evaluate whether they should be referred for an in-depth assessment. In the United States, overweight currently is defined as a BMI at or above the 95th percentile of the 2000 CDC growth charts, and at risk for overweight is defined as a BMI between the 85th and the 95th percentiles for children 2–19 years of age.27Flegal K.M. Tabak C.J. Ogden C.L. Overweight in children: definitions and interpretation.Health Educ Res. 2006; 21: 755-760Crossref PubMed Scopus (60) Google ScholarAlthough no consistent recommendations for the definition of overweight among infants and children younger than 2 years of age exist, nutrition programs such as the Special Supplemental Nutrition Program for Women, Infants, and Children have used weight-for-length to determine overweight and thus program eligibility.49Committee on Scientific Evaluation of WIC Nutrition Risk Criteria Food and Nutrition BoardInstitute of MedicineNational Academy of SciencesSummary of WIC nutrition risk criteria: a scientific assessment.J Am Diet Assoc. 1996; 96: 925-930Abstract Full Text Full Text PDF PubMed Google Scholar Consequently, overweight in this age group often is defined as the 95th percentile or higher of weight-for-length. All these definitions are statistical and the percentile values are age- and sex-specific, so comparisons across age or sex groups should be performed with caution.Prevalence and TrendsPrevalence estimates of obesity usually are derived from surveys or population studies because systematic data on obesity generally cannot be gathered from medical records or vital statistics. Virtually all data on prevalence and trends are based on measurements of weight and height using the classifications described earlier rather than on body fat because of the logistical difficulties involved in measuring body fat in population studies.The NHANES program provides national estimates of overweight for adults, adolescents, and children in the United States. A series of cross-sectional, nationally representative examination surveys conducted by the National Center for Health Statistics of the CDC, the NHANES surveys were designed using stratified multistage probability samples. Currently, NHANES includes oversampling of adolescents, Mexican Americans, and African Americans, among other groups, to improve estimates for these groups. All of the surveys included a standardized physical examination in a mobile examination center with measurement of recumbent length, stature, and weight. Stature was measured in children 2 years and older and recumbent length in children younger than 4 years.50National Center for Health Statistics. NHANES data sets and related documentation. Available: http://www.cdc.gov/nchs/about/major/nhanes/datalink.htm. Accessed October 30, 2006.Google Scholar, 51Miller H.W. Plan and operation of the health and nutrition examination survey United States—1971–1973.Vital Health Stat 1. 1973; 10a: 1-46PubMed Google Scholar, 52McDowell A. Engel A. Massey J.T. Maurer K. Plan and operation of the Second National Health and Nutrition Examination Survey, 1976–1980.Vital Health Stat 1. 1981; 15: 1-144PubMed Google Scholar, 53Plan and operation of the Third National Health and Nutrition Examination Survey, 1988–94 Series 1: programs and collection procedures.Vital Health Stat 1. 1994; 32: 1-407PubMed Google ScholarEstimates of the prevalence of overweight (BMI ≥ 25.0), obesity (BMI ≥ 30.0), and extreme obesity (BMI ≥ 40.0) among adults 20–74 years of age in the United States from the NHANES surveys from 1960 to 2004 are shown in Table 1. Because the surveys before 1988 only included individuals up through 74 years of age, trends are shown for adults 20–74 years of age. Estimates of at risk for overweight (85th percentile ≤ BMI-for-age < 95th percentile) and overweight (BMI-for-age ≥ 95th percentile) for children and adolescents during this same time period are shown in Table 2.Table 1Prevalence and Trends of Overweight and Obesity Among Adults Ages 20–74 Years in the United States: 1960–2004SexSurvey yearaNational Health Examination Survey (1960–1962); National Health and Nutrition Examination Survey (I, 1971–1974; II, 1976–1980; III, 1988–1994; 1999–2000; 2001–2002; 2003–2004).Overweight or obesebSignificant increasing trend for all, men, and women (P < .05).Overweight but not obeseObesebSignificant increasing trend for all, men, and women (P < .05).Extremely obesebSignificant increasing trend for all, men, and women (P < .05).%SE%SE%SE%SEAll1960–196244.9.831.5.513.3.6.9.11971–197447.2.832.7.614.5.41.3.21976–198047.1.832.1.615.0.41.4.11988–199455.9.932.6.623.2.73.0.31999–200064.51.633.61.030.91.65.0.62001–200265.7.734.41.131.31.25.4.52003–200466.21.
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