Are BMI and other anthropometric measures appropriate as indices for obesity? A study in an Asian population

Abstract

We have examined the relationships between percentage of body fat (PBF) and risk factors for cardiovascular disease and insulin resistance and how good body mass index (BMI) and other anthropometric measures are as indices of obesity. High PBF levels were associated with increased risk of cardiovascular disease and insulin resistance. The World Health Organization BMI of 30 kg/m2 for obesity has low sensitivity, 6.7% and 13.4% for men and women, respectively. For every obese man and woman identified, 6.7 and 1.76 times nonobese men and women, respectively, will be misclassified as obese. With the locally established BMI cutoff point for obesity of 27 kg/m2 for men and 25 kg/m2 for women, the sensitivity was improved to 46.7% and 60.8%, respectively. For every obese man and woman identified, 3.76 and 1.64 times nonobese men and women, respectively, will be misclassified as obese. None of the other anthropometric indices was better than the locally established BMIs.We showed that the BMIs for obesity for our local men and women are different. These BMIs were most precise among all indices studied. However, they still lead to high false-positive rates. For more effective management of the problem of obesity, we need to develop more precise, simple, and cost-effective methods for the measurement of PBF. We have examined the relationships between percentage of body fat (PBF) and risk factors for cardiovascular disease and insulin resistance and how good body mass index (BMI) and other anthropometric measures are as indices of obesity. High PBF levels were associated with increased risk of cardiovascular disease and insulin resistance. The World Health Organization BMI of 30 kg/m2 for obesity has low sensitivity, 6.7% and 13.4% for men and women, respectively. For every obese man and woman identified, 6.7 and 1.76 times nonobese men and women, respectively, will be misclassified as obese. With the locally established BMI cutoff point for obesity of 27 kg/m2 for men and 25 kg/m2 for women, the sensitivity was improved to 46.7% and 60.8%, respectively. For every obese man and woman identified, 3.76 and 1.64 times nonobese men and women, respectively, will be misclassified as obese. None of the other anthropometric indices was better than the locally established BMIs. We showed that the BMIs for obesity for our local men and women are different. These BMIs were most precise among all indices studied. However, they still lead to high false-positive rates. For more effective management of the problem of obesity, we need to develop more precise, simple, and cost-effective methods for the measurement of PBF. With increasing affluence and a rapidly aging population, lifestyle diseases such as cancers and coronary heart disease have become the major causes of death in Singapore (1Ministry of Home Affairs Report of the Registry of Births and Deaths. Ministry of Home Affairs, Singapore2000Google Scholar). Coronary heart disease is the second leading cause of death, accounting for 24.5% of all deaths in 2000 (2Lipids – Ministry of Health Clinical Practice Guidelines. Ministry of Health of Singapore, November 2001www.moh.gov.sg/cmaweb/attachments/Google Scholar). This mortality rate is comparable to those observed in the West and higher than those in other parts of Asia, such as Japan and Hong Kong (3World Health Organization WHO Statistics Annals 1996. World Health Organization, Geneva1998Google Scholar). A key issue in the management of coronary heart disease is prevention. Many of the predisposing risk factors, including obesity, can be prevented or modified through appropriate lifestyle changes and medical treatment. The body mass index (BMI) has been used routinely to classify subjects as obese or nonobese. The World Health Organization (WHO) and the International Obesity Task Force recommend the BMI cutoff point of 30 kg/m2 for obesity. This cutoff point was derived largely from mortality statistics from European and American populations. Several studies carried out mainly among Asian populations have challenged the notion that one BMI cutoff point fits all populations. They have separately established that the BMI cutoff point for obesity for Asian populations is pegged between 23 and 27 kg/m2 (4Deurenberg P. Yap M. van Staveren W.A. Body mass index and percent body fat: a meta analysis among different ethnic groups.Int. J. Obes. Relat. Metab. Disord. 1998; 22: 1164-1171Crossref PubMed Scopus (1004) Google Scholar, 5Stevens J. Nowicki E.M. Body mass index and mortality in Asian populations: implications for obesity cut-points.Nutr. Rev. 2003; 61: 104-107Crossref PubMed Scopus (53) Google Scholar, 6Ko G.T. Tang J. Chan J.C. Sung R. Wu M.M. Wai H.P. Chen R. Lower BMI cut-off value to define obesity in Hong Kong Chinese: an analysis based on body fat assessment by bioelectrical impedance.Br. J. Nutr. 2001; 85: 239-242Crossref PubMed Google Scholar, 7Wang J. Thornton J.C. Russell M. Burastero S. Asians have lower body mass index (BMI) but higher percent body fat than do whites: comparisons of anthropometric measurements.Am. J. Clin. Nutr. 1994; 60: 23-28Crossref PubMed Scopus (661) Google Scholar, 8He M. Tan K.C. Li E.T. Kung A.W. Body fat determination by dual energy X-ray absorptiometry and its relation to body mass index and waist circumference in Hong Kong Chinese.Int. J. Obes. Relat. Metab. Disord. 2001; 25: 748-752Crossref PubMed Scopus (134) Google Scholar, 9Chang C.J. Wu C.H. Chang C.S. Yao W.J. Yang Y.C. Wu J.S. Lu F.H. Low body mass index but high percent body fat in Taiwanese subjects: implications of obesity cutoffs.Int. J. Obes. Relat. Metab. Disord. 2003; 27: 253-259Crossref PubMed Scopus (195) Google Scholar). Furthermore, studies have shown that Asian populations have high risks of type 2 diabetes, cardiovascular disease, and mortality from other causes at relatively lower BMI, which they postulated to be largely attributable to the higher proportion of body fat in Asian populations (10Norgan N.G. Population differences in body composition in relation to the body mass index.Eur. J. Clin. Nutr. 1994; 48 (discussion 26–27.): 10-25PubMed Google Scholar, 11Deurenberg-Yap M. Schmidt G. van Staveren W.A. Deurenberg P. The paradox of low body mass index and high body fat percentage among Chinese, Malays and Indians in Singapore.Int. J. Obes. Relat. Metab. Disord. 2000; 24: 1011-1017Crossref PubMed Scopus (439) Google Scholar, 12Dudeja V. Misra A. Pandey R.M. Devina G. Kumar G. Vikram N.K. BMI does not accurately predict overweight in Asian Indians in northern India.Br. J. Nutr. 2001; 86: 105-112Crossref PubMed Google Scholar, 13Deurenberg-Yap M. Chew S.K. Deurenberg P. Elevated body fat percentage and cardiovascular risks at low body mass index levels among Singaporean Chinese, Malays and Indians.Obes. Rev. 2002; 3: 209-215Crossref PubMed Scopus (254) Google Scholar, 14Deurenberg P. Deurenberg-Yap M. Foo L.F. Schmidt G. Wang J. Differences in body composition between Singapore Chinese, Beijing Chinese and Dutch children.Eur. J. Clin. Nutr. 2003; 57: 405-409Crossref PubMed Scopus (78) Google Scholar, 15Deurenberg-Yap M. Chew S.K. Lin V.F. Tan B.Y. van Staveren W.A. Deurenberg P. Relationships between indices of obesity and its co-morbidities in multi-ethnic Singapore.Int. J. Obes. Relat. Metab. Disord. 2001; 25: 1554-1562Crossref PubMed Scopus (156) Google Scholar, 16Tai E.S. Ho S.C. Fok A.C. Tan C.E. Measurement of obesity by anthropometry and bioelectric impedance analysis: correlation with fasting lipids and insulin resistance in an Asian population.Ann. Acad. Med. Singapore. 1999; 28: 445-450PubMed Google Scholar). Therefore, it has been suggested that lower BMI cutoff points for obesity appropriate for Asian populations should be adopted. In its Lancet publication in 2004, the WHO Expert Consultation, after a meta-analysis of population data from more than 10 countries, noted that the proportion of Asian people with a high risk of type 2 diabetes and cardiovascular disease is substantial at BMIs lower than the existing WHO cutoff point for overweight (≥25 kg/m2). The consultation also agreed that the WHO BMI cutoff points should be retained as international classifications and suggested lower BMI action points of 23 and 27.5 kg/m2, which individual countries could use to define the cutoff points for increased risk for their populations (17WHO Expert Consultation Appropriate body-mass index for Asian populations and its implications for policy and intervention strategies.Lancet. 2004; 363: 157-163Abstract Full Text Full Text PDF PubMed Scopus (8214) Google Scholar). In this study, we analyzed a subset of data from our ongoing study of the determinants of the aging process in an Asian population. Specifically, we sought to answer the question of whether the BMI and other anthropometric measures are appropriate indices for obesity. A total of 1,069 healthy subjects, 298 men and 771 women between 30 and 70 years old, were included in this analysis. Subjects were recruited from the general public. Only subjects with no known existing or history of major medical illness, such as cancer, hypertension, thyroid dysfunction, diabetes, osteoporotic fracture, and cardiovascular events, were included in the study. This study was sanctioned by the National University of Singapore. Informed consent was obtained from each volunteer. Because 96.7% of all subjects in this study were Chinese, the results and inferences are applicable to this ethnic group, which make up the majority (76%) of the Singaporean population. Each subject answered a detailed questionnaire that included questions on medical, dietary, social, and sex history, family history of dyslipidemia, and other relevant information concerning the consumption of hormones and food supplements. The body weight was measured without shoes using an electronic measuring scale, and height to the nearest centimeter was taken. The BMI was calculated as weight in kilograms divided by height (in meters squared). Waist circumference (WC) in centimeters was measured midway between the lower costal margin and the iliac crest during the end-expiratory phase Health Expert The and of Report World Health Scholar). circumference in centimeters was measured at the of the Health Expert The and of Report World Health Scholar). The was as the waist circumference divided by the and the was as the waist circumference divided by the height in X-ray absorptiometry has been used for of the percentage of body fat (PBF) and to with other including and and A. J. A of methods to body composition 22: PubMed Google Scholar, for body of J. Nutr. PubMed Scopus Google Scholar, that an assessment of body 1998; PubMed Scopus Google Scholar, E.M. M. In of body composition from X-ray PubMed Scopus Google Scholar, A. A. of BMI to a X-ray absorptiometry of J. Nutr. 1999; PubMed Google Scholar). Each subject a by PBF was by the and the percentage was used to the total PBF. fasting was and levels of total and were measured using an was after of with and C.J. Wu C.H. Lu F.H. Wu J.S. Yao W.J. by of of X-ray Clinical implications of body fat 1999; 22: PubMed Scopus Google Scholar). was to the The of to was used as the index lipids in from the Health The 86: PubMed Scopus Google Scholar). levels of were measured using the at the National University levels of insulin were measured by an with from and the of analysis was based on the showed of of than were using for We at statistics and also and and correlation The sensitivity and for of obesity, which is as a PBF of for men and for women, using BMI, and were based on the was no in between men and the other most lipids and other anthropometric measures in men were higher than the levels in women levels of anthropometric and X-ray PBF in men and women years in men were higher than levels in women in men were higher than levels in women in women were higher than levels in men in men were higher than levels in women in men were higher than levels in women in men were higher than levels in women in men were higher than levels in women in men were higher than levels in women in men were higher than levels in women in men were higher than levels in women in women were higher than levels in men body mass percentage of body total of to waist in men were higher than levels in women in women were higher than levels in men in a BMI, body mass percentage of body total of to waist from the showed that men have lower PBF from to than do women from to men between the 30 and 70 years have body more than than that for women men than women, and respectively, have high levels all men and women have levels than with more men have high levels of than women The risk in men and women those of and men have high risk than women was higher in men than in more men than women have high levels of and in men and in a The of men and women in the PBF are shown in the PBF of for men and for women as cutoff points for obesity, of local men and of local women were as obese. The percentage of men of and women of overweight was and of men and women in the different PBF in a PBF was associated with increased risks of cardiovascular disease and the risk and insulin levels in men and women in the PBF For increased risk was noted for and PBF increased from to PBF increased to the risk increased for and for the obese in risk was noted for In women, on the other the of increasing PBF on the risk factors was more than in risk was noted for and but not for PBF increased from to The risk increased PBF increased to and all risk factors were than those in the PBF was lower than for those in the PBF in risk was noted for and in the obese factors in different PBF in men and and and 2 2 2 and and 2 and and 2 2 and and and 2 and and and 2 2 and 2 and and and 2 2 and 2 and and and 2 in a and the of the percentage of men and women each PBF have high risk and 25 men in the overweight have high and levels with the low PBF In the obese more men have high and and low levels with the overweight A was noted for women, that in the obese body more women have high and with those in the overweight body of women with and 25 in the PBF In men and women, BMI was not with between BMI and PBF were the between PBF calculated BMIs for men and In men and women, the BMIs were with the PBF by the derived from the shown in the BMIs to a body fat of for men and for women were 27 and 25 kg/m2, respectively, and the BMIs for PBF of and for men and and for women were 25 and 23 kg/m2, respectively. the differences in sensitivity and derived from the for the different including those for the and locally established BMI cutoff points for obesity. the BMI cutoff point for obesity for men and women has high and respectively, the sensitivity was 6.7% and The of obesity in men and women were and respectively. this is that the BMI of 30 kg/m2 was between and of obese women and men will be misclassified as nonobese. the other and of nonobese men and women, respectively, will In the BMI cutoff points of 27 kg/m2 for men and 25 kg/m2 for women were the sensitivity for was increased to 46.7% and 60.8%, respectively. However, the false-positive were increased to These of false-positive based on the locally appropriate BMI cutoff points be in the of the of obesity for men and women based on PBF. this is that more nonobese men than obese men will be as the proportion of nonobese women as obese women will be misclassified as and based on of anthropometric and 30 27 30 25 in a For the other anthropometric measures and showed sensitivity and with the BMI cutoff point of 27 kg/m2 the cutoff points of and for women, the sensitivity from to and the were to the BMI cutoff point of 25 kg/m2 For in women, the sensitivity was and the was The WHO obesity as a of fat to the that and are The cutoff points for obesity for men and women to PBF of and Health Expert The and of Report World Health Scholar, Health Organization and the Report on a WHO Consultation on World Health Organization, Scholar, P. J.C. Body mass index as a of body and J. Nutr. PubMed Scopus Google Scholar). We have used the a for the PBF. the is more in the it is not for use with a as in the study. was noted in the study by Deurenberg-Yap M. Schmidt G. van Staveren W.A. Deurenberg P. Body fat measurement among Singaporean Chinese, Malays and a study using a and different J. Nutr. 2001; 85: PubMed Google that with the the PBF PBF in men and However, of those data also the and of the differences for all M. Schmidt G. van Staveren W.A. Deurenberg P. Body fat measurement among Singaporean Chinese, Malays and a study using a and different J. Nutr. 2001; 85: PubMed Google Scholar). the PBF cutoff points for obesity, the of obesity among our healthy population was for men and for Furthermore, we have shown that increasing PBF in men and women, to levels the overweight and obese cutoff was associated with higher levels of and and lower levels of the classifications based on PBF in the study showed that obesity was associated with increased risks of coronary heart disease and type 2 diabetes, as was shown M. Chew S.K. Deurenberg P. Elevated body fat percentage and cardiovascular risks at low body mass index levels among Singaporean Chinese, Malays and Indians.Obes. Rev. 2002; 3: 209-215Crossref PubMed Scopus (254) Google Scholar, 15Deurenberg-Yap M. Chew S.K. Lin V.F. Tan B.Y. van Staveren W.A. Deurenberg P. Relationships between indices of obesity and its co-morbidities in multi-ethnic Singapore.Int. J. Obes. Relat. Metab. Disord. 2001; 25: 1554-1562Crossref PubMed Scopus (156) Google Scholar, Health Organization and the Report on a WHO Consultation on World Health Organization, Scholar, K.C. diseases in Chinese, and Indians in Singapore. Differences in PubMed Scopus Google Scholar). Obesity is a subset of is overweight is obese. This is shown in body have high BMI but low PBF. Therefore, it is that BMI is a of body weight and not of obesity. Many studies have shown that the BMI cutoff points for the classifications as overweight and obese from those by For Asian including those from Hong and Singapore, and also a population, the BMI cutoff points for overweight and obese were 23 kg/m2 and kg/m2, G.T. Tang J. Chan J.C. Sung R. Wu M.M. Wai H.P. Chen R. Lower BMI cut-off value to define obesity in Hong Kong Chinese: an analysis based on body fat assessment by bioelectrical impedance.Br. J. Nutr. 2001; 85: 239-242Crossref PubMed Google Scholar, 8He M. Tan K.C. Li E.T. Kung A.W. Body fat determination by dual energy X-ray absorptiometry and its relation to body mass index and waist circumference in Hong Kong Chinese.Int. J. Obes. Relat. Metab. Disord. 2001; 25: 748-752Crossref PubMed Scopus (134) Google Scholar, N.G. Population differences in body composition in relation to the body mass index.Eur. J. Clin. Nutr. 1994; 48 (discussion 26–27.): 10-25PubMed Google Scholar, 11Deurenberg-Yap M. Schmidt G. van Staveren W.A. Deurenberg P. The paradox of low body mass index and high body fat percentage among Chinese, Malays and Indians in Singapore.Int. J. Obes. Relat. Metab. Disord. 2000; 24: 1011-1017Crossref PubMed Scopus (439) Google Scholar, Chang and body mass index of in A Med. 2000; PubMed Scopus Google Scholar, M. R. M. Body mass index (BMI) and percent fat A BMI 27.5 kg/m2 could be of obesity in the Clin. 2001; PubMed Scopus Google Scholar, M. Deurenberg P. a of WHO body mass index cut-off The of Asians in Rev. 2003; 61: PubMed Google Scholar, M. Tan K.C. Li E.T. Kung A.W. Body fat determination by dual energy X-ray absorptiometry and its relation to body mass index and waist circumference in Hong Kong Chinese.Int. J. Obes. Relat. Metab. Disord. 2001; 25: 748-752Crossref PubMed Scopus Google Scholar). was a need to the cutoff for obesity in Asian populations. and the to study the relationships between BMI and we have shown that the BMI cutoff point for obesity for our local healthy men and women years was 27 and 25 kg/m2, respectively, with by Asian G.T. Tang J. Chan J.C. Sung R. Wu M.M. Wai H.P. Chen R. Lower BMI cut-off value to define obesity in Hong Kong Chinese: an analysis based on body fat assessment by bioelectrical impedance.Br. J. Nutr. 2001; 85: 239-242Crossref PubMed Google Scholar, 8He M. Tan K.C. Li E.T. Kung A.W. Body fat determination by dual energy X-ray absorptiometry and its relation to body mass index and waist circumference in Hong Kong Chinese.Int. J. Obes. Relat. Metab. Disord. 2001; 25: 748-752Crossref PubMed Scopus (134) Google Scholar, N.G. Population differences in body composition in relation to the body mass index.Eur. J. Clin. Nutr. 1994; 48 (discussion 26–27.): 10-25PubMed Google Scholar, 11Deurenberg-Yap M. Schmidt G. van Staveren W.A. Deurenberg P. The paradox of low body mass index and high body fat percentage among Chinese, Malays and Indians in Singapore.Int. J. Obes. Relat. Metab. Disord. 2000; 24: 1011-1017Crossref PubMed Scopus (439) Google Scholar, Chang and body mass index of in A Med. 2000; PubMed Scopus Google Scholar, M. Deurenberg P. a of WHO body mass index cut-off The of Asians in Rev. 2003; 61: PubMed Google Scholar, M. Tan K.C. Li E.T. Kung A.W. Body fat determination by dual energy X-ray absorptiometry and its relation to body mass index and waist circumference in Hong Kong Chinese.Int. J. Obes. Relat. Metab. Disord. 2001; 25: 748-752Crossref PubMed Scopus Google Scholar). we from studies is in the of a in BMI cutoff for obesity for Asian men and women this be BMI is used as an index of obesity for Asian populations. The of a for obesity not on high sensitivity but also high low shown that the BMI cutoff points for obesity are different between Asian men and women and from that by the question is how good are BMI cutoff points as indices for for obesity in the local the we have derived sensitivity and for BMIs and other anthropometric indices in obese in our population. by using the BMI cutoff point of 30 kg/m2 for obesity, which showed a sensitivity of 6.7% and 13.4% for men and women, respectively, the majority of the of obese men and of obese women in our population have been In of nonobese men and of nonobese women be misclassified as obese. In the was more For the BMI of 30 kg/m2 was used as a cutoff for obesity, for every obese man identified, will be and 6.7 nonobese men will be misclassified as obese. For women, the was better but not For every obese woman identified, will be and nonobese women will be misclassified as obese. results do not for a BMI of 30 kg/m2 as the cutoff point for obesity in Asian men and the locally established BMI of 27 kg/m2 for men and 25 kg/m2 for women, the sensitivity was of obese men and of obese women will be However, for every obese man and obese woman identified, will be 3.76 and 1.64 times nonobese men and women, respectively, that will be misclassified as obese. For the other anthropometric measures for obesity, and and the sensitivity and were to those of the BMI of 27 In women, the sensitivity and for and were to but lower than the levels for BMI of 25 for the sensitivity and were lower and respectively, than those for BMI of 25 This is attributable to the that the of body fat in women is different from that in with fat in men more and fat in for women more The is a that fat is is not a good of the other anthropometric measures in men and women is better as an index for obesity than the locally established BMIs for men and women kg/m2). However, BMI cutoff points were to be used as indices for obesity for local men and women, a be in to the high levels of false-positive classifications of nonobese men and is to such as the use of more PBF methods of on all intervention is this the of of nonobese as obese. the other the problem of high is more to is no with the use of the BMI to obese be misclassified as nonobese. High or false-positive lead to obese as and as with the of obese the appropriate and to the of obese to that is not The of obesity, with its high risks of in countries, including Singapore, is Many countries are in with the WHO and the International Obesity Task Force to this shown in this study, BMIs for the local population have improved sensitivity but are still by high false-positive for locally established BMI cutoff points are better indices for of obesity that of the anthropometric indices studied. However, to better in to the of the increasing of obesity, more precise indices for obesity need to be is an need to on existing methods and to develop simple, and cost-effective methods for of PBF that obesity can be more suggested by Deurenberg-Yap M. Schmidt G. van Staveren W.A. Deurenberg P. Body fat measurement among Singaporean Chinese, Malays and a study using a and different J. Nutr. 2001; 85: PubMed Google and of mass for populations could be established and including could be an that could be used with However, and are major could be a of The the by the of and in this study. The also the medical from the of and National University the of all This study was by the National University of Singapore through the