Obesity Epidemiology

18 STUDY DESIGNS AND MEASUREMENTSFigure 2.2 Obesity by sex and race/ethnicity (NHANES 2003-2004). With permission fromOgden CL, Carroll MD, Curtin LR, McDowell MA, Tabak CJ, Flegal KM. Prevalence ofoverweight and obesity in the United States, 1999-2004. JAMA. 2006;295:1549-1555. 8had the lowest rate (7.8%). 15 In men, the prevalence of obesity did not differ significantlyacross different racial/ethnic groups. 16,17Using self-reported data from the 2000 National Health Interview Survey, Goel et al. 18reported a lower prevalence of obesity in immigrants (16%) compared with U.S.-born individuals(22%). However, the prevalence among immigrants living in the United States forat least 15 years approached that of U.S.-born adults. 18 Lauderdale and Rathouz 19 foundsimilar results among Asian American ethnic groups. The longer foreign-born individualslived in the United States, the higher their risk of being overweight or obese.There has been a close association between socioeconomic status (SES) and obesity,particularly in women. 20 In general, low-SES groups in industrialized countries aremore likely to be obese than their high-SES counterparts, whereas in developingnations, high-SES groups are more likely to be obese. 21-23 However, the link betweenSES and obesity in the United States has weakened, even as the prevalence of obesityhas dramatically increased. 20 In other words, although obesity is still more common inindividuals with a lower SES, disparities in obesity rates have declined over the pastthree decades. 24 The relative difference in the prevalence of obesity between low- andhigh-SES groups decreased from 50% in NHANES I (1971-1974) to 14% in NHANES(1999-2000). These data are consistent with findings of a greater increase in obesity inthe high-SES group, resulting in a modest association between low-SES and obesityin most gender and ethnic groups. 20 Among black women, those with middle incomesexperienced the largest increase in the prevalence of obesity; for black men, the largestincrease was seen in the high-income group. 24Increase in Central ObesityThe National Cholesterol Education Program (NCEP) includes elevated waist circumference(>40 in./102 cm in men; >35 in./88 cm in women), a measure of central obesity,as one of the five abnormalities that define the metabolic syndrome. 25 Li et al. 26examined secular trends in waist circumference in U.S. adults based on the NHANESconducted between 1988 and 2004. Between the periods of 1988-1994 and 2003-2004,the age-adjusted mean waist circumference increased from 96.0 to 100.4 cm in men andfrom 89.0 to 94.0 cm in women. The age-adjusted abdominal or central obesity increasedfrom 29.5% to 42.4% in men and from 47.0% to 61.3% in women. In 2003-2004, overhalf of U.S. adults had abdominal obesity as defined by the NCEP criterion. In men,