Forecasting the obesity epidemic in the aging U.S. population

Objective: The objective was to forecast BMI distribution in the U.S. population along with demographic changes based on past race‐, sex‐, and birth cohort‐specific secular trends. Research Methods and Procedures: We compiled data from 44,184 subjects from 4 National Health and Nutrition Examination Surveys (NHANES; 1971 to 2004). By race and sex, we fit regression models to create smoothed mean BMI curves by age for 1970 to 2010. Linking corresponding birth cohorts across age‐ and year‐specific mean BMI projections, we estimated the trajectory of relative BMI throughout each cohort's lifetime. These projections were validated using actual cohorts in the Nurses’ Health Study and Health Professionals Follow‐up Study. Combined with U.S. census, we predicted BMI distributions in 2010 and examined the joint impact of the obesity epidemic and population aging. Results: BMI secular trends in the past 3 decades differ significantly by birth cohort, sex, and race. If these trends continue, the prevalence of obesity is expected to reach 35%, 36%, 33%, and 55% in 2010 among white men, white women, black men, and black women, respectively, far from the Healthy People 2010 goal of 15%. Such forecasts translate into 9.3 million more obese adults 20 to 74 years of age than in 2000, 8.3 million of whom would be 50 years of age or older, and 8.5 million of whom would be white. The mean age among obese men and women is also expected to rise from 47 to 49 years among whites and from 43 to 44 years among blacks. Discussion: As the baby boom generation approaches retirement age, the continuing obesity epidemic signals a likely expansion in the population with obesity‐related comorbidities. A framework to combine BMI and demographic trends is essential in evaluating the burden and disparity associated with the epidemic in the aging U.S. population.     

The vanishing weight gap: Trends in obesity among adult food stamp participants (US) (1976–2002)

High rates of obesity among low-income populations have led some to question whether USDA's food assistance programs have contributed to this health problem. Using data from National Health and Nutrition Examination Surveys (NHANES), this study shows that the association between food assistance program participation and body weight measures has weakened over the past three decades. Earlier NHANES data show that program participants were more likely to be overweight than individuals who were eligible but not participating in the program. This was particularly true among white women. However, the more recent data show that these differences have vanished, as the BMI of the rest of the population has caught up to BMI levels of food stamps recipients.     

Socioeconomic status, height, and obesity in children

The substantial increase in the prevalence of child obesity over recent decades and its association with a number of negative health and economic outcomes suggests its strong potential as an influence on the lifecourse development of health and productivity. This paper evaluates interactive effects between family socioeconomic status (SES) and height on child obesity in the United States. Using the 1999-2006 National Health and Nutrition Examination Surveys (NHANES), the results of this paper confirm previous findings that taller children exhibit greater propensity towards obesity as measured by body mass index (BMI) and that obesity is inversely related to family SES as measured by poverty status. The analysis adds to the existing literature by showing that the magnitude of the SES-obesity association is larger in taller children. Age and sex patterns are evaluated that suggest the SES-height interaction persists through childhood and adolescence in males but is only evident in females during adolescence. Interaction effects are also shown to be most evident in white males and Hispanic females. Policy implications are discussed and directions for future work are suggested.     

BMI may overestimate the prevalence of obesity among women of lower socioeconomic status

Objective: Our objective was to examine gender differences in height and weight associated with socioeconomic status (SES) and the consequent effect on body mass index in a multiethnic society. Research Methods and Procedures: A cross‐sectional study, the First Israeli National Health and Nutrition Survey, was performed on a representative population sample of 3246 adults 25 to 64 years of age, between the years 1999 to 2001. Height and weight were measured, and BMI and other weight‐height indices were calculated. SES was assessed by income and education. Results: Age‐adjusted height was significantly lower at lower levels of SES among both women and men (p < 0.001). As opposed to men, women of lower SES were heavier than those of higher SES, and the mean age‐adjusted weight was 4.6 kg higher among those of lower SES (p < 0.001). Thus, using the standard index of BMI, the prevalence of obesity was significantly higher among shorter women. Discussion: In this group of Israeli adults, the unfavorable effect of low SES on BMI was evident among women, partly due to their decreased height combined with increased weight common in this socioeconomic sector. Since BMI is only partly independent of height, it may overestimate the prevalence of obesity among women of lower SES. Alternative measures for classifying obesity in the lower SES groups that put less emphasis on height may be considered and studied.     

Trends in Waist Circumference among U.S. Adults

Objective: Waist circumference has been proposed as a measure of obesity or as an adjunct to other anthropometric measures to determine obesity. Our objective was to examine temporal trends in waist circumference among adults in the U.S. Research Methods and Procedures: We used data from 15, 454 participants ≥20 years old in National Health and Nutrition Examination Survey (NHANES) III (1988 to 1994) and 4024 participants ≥20 years old from National Health and Nutrition Examination Survey 1999 to 2000. Results: The unadjusted waist circumference increased from 95.3 (age‐adjusted, 96.0 cm) to 98.6 (age‐adjusted, 98.9 cm) cm among men and from 88.7 (age‐adjusted 88.9 cm) to 92.2 (age‐adjusted 92.1 cm) cm among women. The percentiles from the two surveys suggest that much of the waist circumference distribution has shifted. Statistically significant increases occurred among all age groups and racial or ethnic groups except men 30 to 59 years old, women 40 to 59 and ≥70 years old, and women who were Mexican American or of “other” race or ethnicity. Discussion: These results demonstrate the rapid increase in obesity, especially abdominal obesity, among U.S. adults. Unless measures are taken to slow the increase in or reverse the course of the obesity epidemic, the burden of obesity‐associated morbidity and mortality in the U.S. can be expected to increase substantially in future years.     

Trends and Disparities in Provider Diagnosis of Overweight Analysis of NHANES 1999–2004

Rates of overweight and obesity are disproportionately high within minority populations. This study examined the trends in provider diagnosis of overweight from 1999 to 2004 and examined whether there were differences in provider diagnosis based on race/ethnicity. We examined data from 4,071 adults with BMI ≥30 who participated in the National Health and Nutrition Examination Surveys (NHANES) (1999–2004). Provider diagnosis was determined by self‐report. From 1999 to 2004, the provider diagnosis of overweight decreased from 71 to 64% (P = 0.003). After controlling for potential confounders, non‐Hispanic blacks and Mexican Americans were less likely to report a provider diagnosis of overweight compared to non‐Hispanic whites. Odds ratio (OR) (95% confidence interval (CI)) for non‐Hispanic blacks was 0.6 (95% CI, 0.4–0.8) and for Mexican Americans was 0.7 (95% CI, 0.4–1.0) compared to non‐Hispanic whites. Reasons for this disparity warrant further investigation.     

BMI and Metabolic Disorders in South Korean Adults: 1998 Korea National Health and Nutrition Survey

Objective: The prevalence of overweight, obesity, and metabolic disorders and their relationship with BMI were studied in South Korean adults. The appropriate BMI categories for overweight and obesity for Koreans were evaluated. Research Methods and Procedures: The 1998 Korea National Health and Nutrition Examination Survey was the first such survey, to our knowledge, conducted on a cross‐sectional and nationally representative population. The survey provided data on body weight; height; fasting serum glucose; triacylglycerol; total, low‐density lipoprotein, and high‐density lipoprotein cholesterol; blood pressure; and various other questions that were incorporated into this study. A total of 39, 060 persons over the age of 1 year from 12, 283 households participated in the Health and Nutrition Interview Survey. Of these, 10, 876 people over the age of 10 years old participated in the Health Examination. We analyzed data from 7962 adults over the age of 20 years old. Results: The overweight (BMI, ≥25.0 to <30.0) and obesity (BMI, ≥30) rates were low among Korean adults: 23.4% and 1.7% in men and 24.9% and 3.2% in women, respectively. However, the prevalences of diabetes, hypertension, and abnormal concentrations of serum triacylglycerol and total, low‐density lipoprotein, and high‐density lipoprotein cholesterol were high at 10.5%, 27.1%, 29.0%, 34.5%, 28.4%, and 37.4%, respectively. These disorders were age dependent, and, in general, there was a strong linear relationship between BMI and the disorders. The relative risk of disorders doubled at a BMI of 23.0 to 24.0 and tripled at a BMI of 26.0, compared with a baseline BMI of 18.5 to 22.0. Discussion: High rates of diabetes, hypertension, and dyslipidemia were noted in middle‐aged and elderly Koreans even at relatively low BMI. It might be appropriate to lower the BMI classification from the current ≥25.0 for overweight and ≥30.0 for obesity for this group of Koreans.     

Gender‐ethnic Disparity in BMI and Waist Circumference Distribution Shifts in US Adults

While obesity has been increasing in the United States, little is known about the variation in recent BMI and waist circumference (WC) distribution shifts across socio‐demographic groups. We assessed shifts in BMI and WC distributions and compared between‐group differences over the past decade, and projected future BMI and WC distributions and prevalence of obesity and central obesity using National Health and Nutrition Examination Survey (NHANES) 1988–1994 and 1999–2004 data. BMI/WC distributional shifts overall and in percentiles were compared across groups. Average yearly shift was calculated and used for projecting future distributions and prevalence. Both BMI and WC increased more in their uppermost percentile distribution, though BMI shift declined toward the uppermost percentiles among women. Heavier Americans gained more adiposity over the past decade. Ethnic (non‐Hispanic (NH) white vs. black) disparities in mean BMI and WC became wider. Over the survey period, mean BMI increased by 1.3 units vs. 1.8 units among men and women, whereas WC, by 4.2 cm vs. 4.8 cm. Young adults had the largest increase. Shift in women's WC was stable between the 25th and 75th percentiles, but gained pace at higher WC, while women's BMI and men's BMI and WC shifts increased linearly. NH black women had the largest shifts and would have central obesity and obesity prevalence of 90.8 and 70.7% by 2020. Shifts in BMI and WC distribution varied across age‐, gender‐, and ethnic groups. Future rise in the obesity and central obesity prevalence rates are expected, but would vary by demographic groups.     

The Changing Body Mass–Mortality Association in the United States: Evidence of Sex-Specific Cohort Trends from Three National Health and Nutrition Examination Surveys

The association between body mass index (BMI) categories and mortality remains uncertain. Using three National Health and Nutrition Examination Surveys covering the 1971–2006 period for cohorts born between 1896 and 1968, this study estimates separately for men and women models for year-of-birth (cohort) and year-of-observation (period) trends in how age-specific mortality rates differ across BMI categories. Among women, relative to the normal weight (BMI 18.5–24.9 kg/m²), there are increasing trends in mortality rates for the overweight (BMI 25–29.9) or obese (BMI ≥ 30). Among men, mortality rates relative to the normal weight decrease for the overweight, do not change for the moderately obese (BMI 30–34.9), and increase for the severely obese (BMI ≥ 35). Period and cohort trends are similar, but the cohort trends are more consistent. In the latest cohorts, compared with the normal weight, mortality rates are 50 percent lower for overweight men, not different for moderately obese men, and 100–200 percent higher for severely obese men and for overweight or obese women. For U.S. cohorts born after the 1920s, a lower overweight than normal weight mortality is confined to men. I speculate on possible reasons why the mortality association with overweight and obesity varies by sex and cohort.     

The Relationship of Ethnicity,Socioeconomic Factors,and Overweight in U.S. Adolescents

Objective: To examine the extent to which race/ethnic differences in income and education account for sex‐specific disparities in overweight prevalence in white, African American, Hispanic, and Asian U.S. teens. Research Methods and Procedures: We used nationally representative data collected from 13,113 U.S. adolescents enrolled in the National Longitudinal Study of Adolescent Health. Logistic regression models were used to examine the relationship of family income and parental education to overweight prevalence (body mass index ≥ 85th percentile of age and sex‐specific cutoff points from the 2000 Centers for Disease Control and Prevention/National Center for Health Statistics growth charts). In addition, we used coefficients from our logistic regression models to project the effects on overweight prevalence of equalizing the socioeconomic status (SES) differences between race/ethnic groups. Results: Keeping adolescents in their same environments and changing only family income and parental education had a limited effect on the disparities in overweight prevalence. Ethnicity‐SES‐overweight differences were greater among females than males. Given that overweight prevalence decreased with increasing SES among white females and remained elevated and even increased among higher SES African‐American females, African‐American/white disparity in overweight prevalence increased at the highest SES. Conversely, disparity was lessened at the highest SES for white, Hispanic, and Asian females. Among males, disparity was lowest at the average SES level. Discussion: One cannot automatically assume that the benefits of increased SES found among white adults will transfer to other gender‐age‐ethnic groups. Our findings suggest that efforts to reduce overweight disparities between ethnic groups must look beyond income and education and focus on other factors, such as environmental, contextual, biological, and sociocultural factors.     

Decomposing adult obesity trends in China (1991–2011)

Using data from the China Health and Nutrition Survey, this study analyses two decades (1991–2011) of change in adult obesity in China with a focus on whether rising obesity rates result from all population cohorts becoming more obese across time (intra-cohort change) or recent cohorts being more obese than their earlier counterparts (inter-cohort change or cohort replacement). To do so, we decompose changes in the body mass index (BMI), waist circumference (WC), general obesity and abdominal obesity of adults aged 20+ using both Firebaugh’s linear decomposition and Das Gupta’s non-linear technique. Our analysis not only reveals significant increases in both general and abdominal obesity (8.1 and 32 percentage points, respectively) in the two decades studied but shows that the rising means in all four measures are mostly attributable to intra-cohort change. In fact, contrary to findings for the U.S., inter-cohort change for the Chinese sample is actually negative, implying that cohort replacement attenuates intra-cohort change over time. Given that intra-cohort change is the central force for the increase in BMI, WC and obesity with individual increases in obesity widely distributed across all cohorts and age groups over time, policy interventions should focus more broadly on all age groups and birth cohorts.     

Educational differences in obesity in the United States: a closer look at the trends

Both body weight and educational attainment have risen in the United States. Empirical evidence regarding educational differences in obesity (BMI ≥30) is inconsistent. According to some widely cited claims, these differences have declined since the 1970s, and the most educated have experienced the greatest gain in obesity. Prior research was limited in grouping college graduates with nongraduates, combining men and women in the same analysis, and using self-reported rather than measured anthropometric information. Using the National Health and Nutrition Examination Surveys (NHANES), we address these issues and examine changing educational differences in obesity from 1971-1980 to 1999-2006 for non-Hispanic whites and blacks in two separate age groups (25-44 vs. 45-64 years). We find that (i) obesity differentials by education have remained largely stable, (ii) compared with college graduates, less educated whites and younger black women continue to be more likely to be obese, (iii) but the differentials are larger for women than men, and weak or nonexistent among black men and older black women. There are exceptions to the overall trend. The obesity gap has widened between the two groups of college-educated younger women, but disappeared between the least and most educated younger white men. Thus, the increase in obesity was similar for most educational groups, but significantly greater for younger women with some college and smaller for younger white men without a high-school degree. Lumping together the two distinct college groups has biased previous estimates of educational differences in obesity.     

Socioeconomic status in relation to obesity and abdominal obesity in Korean adults: a focus on sex differences

Objective: We examined the relationship between income and education level with BMI and waist circumference to provide further understanding of the relationship between socioeconomic status and obesity and to identify the presence of sex differences. Research Methods and Procedures: A total of 7962 people ≥20 years of age (3597 men; 4365 women) who participated in the 1998 Korean National Health and Nutrition Examination Survey provided data including height, weight, waist circumference, education, and income level. We examined adjusted BMI and waist circumference according to level of income and education and the association between income and education with obesity and abdominal obesity by multiple logistic regression analysis. Results: In men, significant dose‐response relationships were noted between income and obesity (trend, p < 0.05) and abdominal obesity (trend, p < 0.05). Compared with the lowest income group, the adjusted odds ratios (ORs) (95% confidence interval) of the highest income group for obesity and abdominal obesity were 1.65 (1.18 to 2.32) and 1.37 (0.94 to 1.98), respectively. However, income was not associated with obesity or abdominal obesity in the fully adjusted models in women. With regard to education, women showed significantly decreased ORs, with inverse trends for obesity and abdominal obesity across all education levels. Compared with the lowest education group, the adjusted ORs (95% confidence interval) for obesity and abdominal obesity were 0.66 (0.57 to 0.76) and 0.40 (0.35 to 0.45), respectively, among women with 7 to 12 years of schooling and 0.27 (0.21 to 0.34) and 0.15 (0.12 to 0.18), respectively, among women with 13 or more years of schooling. Discussion: Socioeconomic difference has a considerable impact on the prevalence of obesity among the Korean population, and the patterns differ substantially across sex.     

Relationship between Body Weight Gain and Significant Knee,Hip, and Back Pain in Older Americans

Objective: To examine the association between BMI (kilograms per meter squared) and reports of significant knee, hip, and back pain using data from a nationally representative sample of U.S. adults 60 years or older. Research Methods and Procedures: Population‐based survey data from the Third National Health and Nutrition Examination Survey, involving 5724 adults 60 years or older, were used. BMI, calculated from measured weight (kilograms) and height (meters squared), was used to categorize participants into six BMI‐defined groups: underweight (<18.5), desirable weight (18.5 to 24.9), overweight (25 to 29.9), obese class I (30 to 34.9), obese class II (35 to 39.9), and obese class III (≥40). The presence of significant knee, hip, and back pain in the groups was studied. Results: The overall prevalences of knee, hip, and back pain were 21%, 14%, and 22%, respectively. Prevalence estimates for knee (underweight 12.1% to obesity class III 55.7%), hip (underweight 10.4% to obesity class III 23.3%), and back (underweight 20.2% to obesity class III 26.1%) pain increased with increased BMI. Sex‐, race‐, and age‐specific pain prevalence estimates also generally increased at increased levels of BMI. Discussion: Among U.S. adults 60 years or older, the prevalence of significant knee, hip, and back pain increases with increased levels of BMI.     

Racial and ethnic differences in secular trends for childhood BMI, weight, and height

Objectives: The prevalence of childhood overweight in the United States has markedly increased over the last 30 years. We examined differences in the secular trends for BMI, weight, and height among white, black, and Mexican‐American children. Research Methods and Procedures: Analyses were based on nationally representative data collected from 2 to 17 year olds in four examinations (1971–1974 through 1999–2002). Results: Overall, black children experienced much larger secular increases in BMI, weight, and height than did white children. For example, over the 30‐year period, the prevalence of overweight increased ～3‐fold (4% to 13%) among 6‐ to 11‐year‐old white children but 5‐fold (4% to 20%) among black children. In most sex‐age groups, Mexican‐American children experienced increases in BMI and overweight that were between those experienced by blacks and whites. Race/ethnicity differences were less marked among 2 to 5 year olds, and in this age group, white children experienced the largest increase in overweight (from 4% to 9%). In 1999–2002, the prevalence of extreme BMI levels (≥99th percentile) reached 6% to 7% among black girls and Mexican‐American boys. Discussion: Because of the strong tracking of childhood BMI levels into adulthood, it is likely that the secular increases in childhood overweight will greatly increase the burden of adult disease. The further development of obesity interventions in different racial/ethnic groups should be emphasized.     

Trends in Childhood Obesity in Japan over the Last 25 Years from the National Nutrition Survey

Objective: To describe the 25‐year changes in BMI (measured in kilograms per meters squared) and the prevalence of obesity in Japanese children with special reference to urban‐rural differences. Research Methods and Procedures: We used the data sets from the cross‐sectional annual nationwide surveys (National Nutrition Survey, Japan) conducted from 1976 to 2000 and comprising 29, 052 boys and 27, 552 girls between 6 and 14 years of age. We carried out the trend analyses with the data on sex and age groups and on residential areas according to the size of the municipality (metropolitan areas, cities, and small towns). Results: The mean (age‐adjusted) BMI increased by +0.32 kg/m² per 10 years in boys and by +0.24 kg/m² per 10 years in girls, increases that were remarkable in small towns. The prevalence of obese boys and girls increased from 6.1% and 7.1%, respectively, in the time‐period 1976 to 1980, to 11.1% and 10.2% in 1996 to 2000. The increasing trend was most evident in 9‐ to 11‐year‐old children of both sexes living in small towns, whereas no changes were observed in girls in metropolitan areas. Discussion: Our data clearly show increasing trends in obesity prevalence in Japanese school children. Degrees of the increasing trends, however, differed across sex and age groups and residential areas, demonstrating a particular phenomenon that girls in metropolitan areas were unlikely to become obese. These epidemiological aspects indicate the priorities for intervention in population strategies to control obesity in children.     

Night eating: prevalence and demographic correlates

Objective: To examine the prevalence and correlates of night eating, the core behavioral symptom of night eating syndrome among adolescents and adults, using two public access survey databases of nationally representative samples. Research Methods and Procedures: Data were extracted for individuals age 13 years or older who completed food diary data for the National Health and Nutrition Examination Survey III (N = 18, 407) or the Continuing Survey of Food Intakes by Individuals (N = 10, 741). Prevalence estimates were calculated for three commonly used definitions of night eating. Logistic regression was used to examine correlates of night eating: type of day, season, gender, age, race/ethnicity, and BMI or obesity. Results: With few exceptions, findings were similar in the two surveys. Night eating is most common during the weekend; prevalence is greatest among young adults (18 to 30 years of age) and least common among individuals age 65 years or older; and is not associated with BMI or obesity. Gender or ethnicity effects were not found to be stable across surveys. Discussion: Experts need to consider type of day, age group, and possibly gender and race/ethnicity when examining population differences in night eating. Longitudinal studies are needed to further examine the link between night eating and obesity.     

Asthma and Maternal Body Mass Index Are Related to Pediatric Body Mass Index and Obesity: Results from the Third National Health and Nutrition Examination Survey

Objective: Clinical research has shown an increased prevalence of obesity in children with asthma. This study was designed to assess the relationship between asthma and pediatric body mass index (BMI) in a national database and to examine factors that may modify this relationship. Design: The cross‐sectional relationship between asthma and pediatric BMI and obesity (BMI ≥ 85th percentile) was studied. Variables that may influence the relationship between asthma and pediatric BMI, such as race/ethnicity and television watching were included in the model for the total sample. A smaller sample of 3009 white and African American youth were studied in regression models including maternal BMI. Study Population: A nationally representative crosssectional sample of 5154 children and adolescents of 6 to 16 years of age from the Third National Health And Nutrition Examination Survey. Results: In the full sample, asthma and television watching were related to BMI, accounting for 3% of the variance in BMI. When maternal BMI was included in the nonHispanic sample, television watching, maternal BMI, and the interaction of maternal BMI and asthma were related to youth BMI, accounting for 15% of the variance. The standardized BMI z‐score for those youth without asthma and no maternal obesity was 0.06, which increased to 0.33 if the youth had asthma, to 0.70 if the youth did not have asthma but the mother was obese, and to 1.71 if the youth had asthma and the mother was obese. Asthma, television watching, and maternal BMI were independent predictors of youth obesity. Conclusions: BMI and prevalence of obesity is higher in youth with asthma. Pediatric BMI, but not obesity, is also related to the interaction of asthma and maternal BMI in white and African American youth. Comorbidity of asthma and obesity may complicate treatment of either condition, and prevention of obesity should be encouraged for asthmatic children.     

Trends of Abdominal Adiposity in White,Black, and Mexican‐American Adults, 1988 to 2000

Objective: To describe changes in the distribution of waist circumference (WC) and abdominal obesity (AO) in white, black, and Mexican‐American adults from 1988 through 2000. Research Methods and Procedures: Nationally representative cross‐sectional surveys of adults 20 to 79 years of age were examined using data from U.S. National Health and Nutrition Examination Surveys of 1988 to 1994 and 1999 to 2000. AO was defined as WC ≥102 cm in men and ≥88 cm in women. Results: There was a gradient of increasing WC and AO with increasing age in both study periods in whites and blacks. In men, the average increase between the study periods in overall WC in whites, blacks, and Mexican Americans were 3, 3.3, and 3.4 cm, respectively. The corresponding values in women were 2.4, 5.3, and 3.7 cm, respectively. In men, the percentage change in prevalence of AO between 1988 and 2000 ranged from 5.5% in Mexican‐American men to 8.2% in white men. In women, there was a 1.7% decrease in AO in Mexican Americans, whereas there was an increase of 6.3% for whites and 7% for blacks. Discussion: Despite increased understanding of the need for screening and treatment for obesity, this study indicates increasing prevalence of AO in white and black Americans. Without concerted effort to reduce the prevalence of overall obesity, the increasing prevalence of AO is likely to lead to increased prevalence of metabolic syndromes in the United States. Our results highlight the need to design evidence‐based programs that show promise for long‐term health behavior changes to facilitate the prevention of AO and related comorbidities.     

Development of Health‐Related Waist Circumference Thresholds Within BMI Categories

Objective: To develop and cross‐validate waist circumference (WC) thresholds within BMI categories. The utility of the derived values was compared with the single WC thresholds (women, 88 cm; men, 102 cm) recommended by NIH and Health Canada. Research Methods and Procedures: The sample included adults classified as normal weight (BMI = 18.5 to 24.9), overweight (BMI = 25 to 29.9), obese I (BMI = 30 to 34.9), and obese II+ (BMI ≥ 35) from the Third U.S. National Health and Nutrition Examination Survey (NHANES III; n = 11, 968) and the Canadian Heart Health Surveys (CHHS; n = 6286). Receiver operating characteristic curves were used to determine the optimal WC thresholds that predicted high risk of coronary events (top quintile of Framingham scores) within BMI categories using the NHANES III. The BMI‐specific WC thresholds were cross‐validated using the CHHS. Results: The optimal WC thresholds increased across BMI categories from 87 to 124 cm in men and from 79 to 115 cm in women. The validation study indicated improved sensitivity and specificity with the BMI‐specific WC thresholds compared with the single thresholds. Discussion: Compared with the recommended WC thresholds, the BMI‐specific values improved the identification of health risk. In normal weight, overweight, obese I, and obese II+ patients, WC cut‐offs of 90, 100, 110, and 125 cm in men and 80, 90, 105, and 115 cm in women, respectively, can be used to identify those at increased risk.