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Can Body Mass Index (BMI) be used as a proxy for somatotype?
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The Social Science Journal 46 (2009) 390–393
Can Body Mass Index (BMI) be used as a proxy for somatotype? Jeremy E.C. Genovese Department of Curriculum and Foundations, Cleveland State University, 2121 Euclid Avenue, Cleveland, OH 44115, USA
Abstract In a paper published in The Social Science Journal, Maddan et al. [Maddan, S., Walker, J. T., & Miller, J. M. (2008). Does size really matter? A reexamination of Sheldon’s somatotypes and criminal behavior. The Social Sciences Journal, 45, 330–344.] proposed that Body Mass Index (BMI) can be used as proxy for somatotype, a quantitative system for describing body build, in social science research. This paper tests this proposal using a sample of 200 males from an archival data set collected by Sheldon [Sheldon, W. H. (1942). The varieties of temperament: A psychology of constitutional differences (with S.S. Stevens). New York: Harper and Row Publishers.]. The data included somatotype data, height, and weight. BMI was calculated and individuals were assigned to the categories endomorph, mesomorph, and ectomorph based on the Maddan et al. BMI criteria. The BMI method was only able to correctly classify 110 individuals, 55% of the sample. This finding suggests that BMI is an inadequate proxy for somatotype. © 2009 Western Social Science Association. Published by Elsevier Inc. All rights reserved.
Somatotype is the name given to the system for describing human physique in terms of three components; endomorphy, mesomorphy, and ectomorphy. Endomorphy is a measure of the fat component of the body, mesomorphy captures the body’s muscularity, while ectomorphy referrers to the body’s linearity. An individual’s somatotype is represented by a set of three measurements, one for each component and each component on a scale from 1 to 7. While somatotype has been found to predict a number of health conditions (Singh, 2007) and to be correlated with important behavioral variables (Genovese, 2008) it has been underutilized by researchers. One explanation for this underutilized may simply be the difficulty in obtaining E-mail address: [email protected]. 0362-3319/$ – see front matter © 2009 Western Social Science Association. Published by Elsevier Inc. All rights reserved. doi:10.1016/j.soscij.2009.04.007
J.E.C. Genovese / The Social Science Journal 46 (2009) 390–393
391
accurate somatotype data. Somatotyping involves multiple anthropomorphic measures and photography of the subjects. In a recent paper, Maddan, Walker, and Miller (2008) suggested an alternative; they proposed that Body Mass Index (BMI) may be used as proxy for somatotype. BMI is the weight in kilograms divided by the square of the height in meters. Maddan et al. suggested that a person with a BMI equal to or greater than 26 can be classified as an endomorph, a person with a BMI between 19 and 25 can be classified as a mesomorph, and an individual with a BMI below 19 can be considered an ectomorph. If Maddan et al. (2008) are correct and BMI can be reasonably translated into somatotype then new avenues of research would be opened. Since height and weight (the components of BMI) data are collected in many clinical and research contexts, it would now be possible to expand somatotype research greatly. The purpose of this paper is to test how well BMI captures somatotype using an archival sample collected by Sheldon (1942) that includes somatotype, height, and weight, for 200 young adult men.
1. Method 1.1. Sample In 1942, Sheldon, the inventor of somatotyping, published a study of 200 White male university students and graduates. Ages ranged from 17 to 31, with a mean of 23.3. In an appendix to his study Sheldon included somatotype ratings, height in inches, and weight in pounds for all 200 participants. 1.2. Analysis The data were entered into SPSS. BMI was calculated using the standard formula; (weight in pounds × 703)/(height in inches squared) (Oria et al., 2005). Using BMI scores individuals were assigned to a somatotype category based on the criteria suggested by Maddan et al. (2008). One difficulty in evaluating somatotype classification by BMI is that this method assigns all individuals to a single discrete somatotype; endomorph, mesomorph, or ectomorphs, while in Sheldon’s system individuals receive ratings on each scale. Sheldon did, however, create a graphic system for plotting the relationship between somatotypes called a somatochart. According to Parnell (1958) position in a somatochart allows us to assign most individuals to one of the three categories: “At the center will be found somatotype 444 with the most balanced body proportions and near to average measurements. Endomorphs (fat persons) lie southwest of this point, muscular mesomorphs lie to the north, and the linear ectomorphs to the southeast (p. 2).”
Using position in the somatochart it was possible to assign 173 individuals to a discrete somatotype category. The remaining 27 fell exactly on a cusp between categories and could not be assigned.
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J.E.C. Genovese / The Social Science Journal 46 (2009) 390–393
Table 1 Somatotype categorization. Sheldon somatotype
Somatotype assigned by Maddan et al. (2008) BMI method Endomorphs
Endomorphs Mesomorphs Ectomorphs Cusp
10 5
Totals
15
Mesomorphs 24 75 34 27 160
Ectomorphs
25 25
Totals 34 80 59 27 200
Note. Correct classifications are in bold.
2. Results Table 1 compares the somatotypes assigned by somatochart and by BMI. Since 27 individuals could not be classified 86.5% is an upper limit for accurate classification. The BMI method was only able to correctly classify 110 individuals, 55% of the sample. The BMI method over identified mesomorphs, giving this label to 160 individuals, 80% of the sample.
3. Discussion While BMI has been widely used as in an indicator of obesity, there has been a growing awareness that it is inadequate for this purpose (Cawly & Burkhauser, 2006). BMI cannot distinguish between individuals who have large bodies because of increased muscle mass or increased fat. Thus, it is not surprising that BMI poorly distinguishes between somatotypes. Maddan et al. (2008) are to be commended for identifying the difficulties with traditional somatotyping procedures and searching for a reasonable proxy. Unfortunately, BMI appears to be a poor substitute. However, it is quite possible that some other measure may allow us to capture body build. In recent years a number of alternatives and supplements to BMI have been proposed (Cawly & Burkhauser, 2006); including percentage of body fat, waist to hip ratio, and waist circumference.
References Cawly, J., & Burkhauser, R. V. (2006). Beyond BMI: The value of more accurate measures of fatness and obesity in social science research (Working Paper No. 12291). Cambridge, MA: National Bureau of Economic Research. Genovese, J. E. C. (2008). Physique correlates with reproductive success in an archival sample of delinquent youth. Evolutionary Psychology, 6, 369–385. Maddan, S., Walker, J. T., & Miller, J. M. (2008). Does size really matter? A reexamination of Sheldon’s somatotypes and criminal behavior. The Social Sciences Journal, 45, 330–344. Oria, H. E., et al. (2005). Guidelines for weight calculations and follow-up in bariatric surgery. Surgery for Obesity and Related Diseases, 1, 67–68.
J.E.C. Genovese / The Social Science Journal 46 (2009) 390–393
393
Parnell, R. W. (1958). Behaviour and physique. London: Edward Arnold Publisher Ltd. Sheldon, W. H. (1942). The varieties of temperament: A psychology of constitutional differences (with S.S. Stevens). New York: Harper and Row Publishers. Singh, S. P. (2007). Somatotype and disease—A review. The Anthropologist: International Journal of Contemporary and Applied Studies of Man, 3, 251–261 [special issue].
The Social Science Journal 46 (2009) 390–393
Can Body Mass Index (BMI) be used as a proxy for somatotype? Jeremy E.C. Genovese Department of Curriculum and Foundations, Cleveland State University, 2121 Euclid Avenue, Cleveland, OH 44115, USA
Abstract In a paper published in The Social Science Journal, Maddan et al. [Maddan, S., Walker, J. T., & Miller, J. M. (2008). Does size really matter? A reexamination of Sheldon’s somatotypes and criminal behavior. The Social Sciences Journal, 45, 330–344.] proposed that Body Mass Index (BMI) can be used as proxy for somatotype, a quantitative system for describing body build, in social science research. This paper tests this proposal using a sample of 200 males from an archival data set collected by Sheldon [Sheldon, W. H. (1942). The varieties of temperament: A psychology of constitutional differences (with S.S. Stevens). New York: Harper and Row Publishers.]. The data included somatotype data, height, and weight. BMI was calculated and individuals were assigned to the categories endomorph, mesomorph, and ectomorph based on the Maddan et al. BMI criteria. The BMI method was only able to correctly classify 110 individuals, 55% of the sample. This finding suggests that BMI is an inadequate proxy for somatotype. © 2009 Western Social Science Association. Published by Elsevier Inc. All rights reserved.
Somatotype is the name given to the system for describing human physique in terms of three components; endomorphy, mesomorphy, and ectomorphy. Endomorphy is a measure of the fat component of the body, mesomorphy captures the body’s muscularity, while ectomorphy referrers to the body’s linearity. An individual’s somatotype is represented by a set of three measurements, one for each component and each component on a scale from 1 to 7. While somatotype has been found to predict a number of health conditions (Singh, 2007) and to be correlated with important behavioral variables (Genovese, 2008) it has been underutilized by researchers. One explanation for this underutilized may simply be the difficulty in obtaining E-mail address: [email protected]. 0362-3319/$ – see front matter © 2009 Western Social Science Association. Published by Elsevier Inc. All rights reserved. doi:10.1016/j.soscij.2009.04.007
J.E.C. Genovese / The Social Science Journal 46 (2009) 390–393
391
accurate somatotype data. Somatotyping involves multiple anthropomorphic measures and photography of the subjects. In a recent paper, Maddan, Walker, and Miller (2008) suggested an alternative; they proposed that Body Mass Index (BMI) may be used as proxy for somatotype. BMI is the weight in kilograms divided by the square of the height in meters. Maddan et al. suggested that a person with a BMI equal to or greater than 26 can be classified as an endomorph, a person with a BMI between 19 and 25 can be classified as a mesomorph, and an individual with a BMI below 19 can be considered an ectomorph. If Maddan et al. (2008) are correct and BMI can be reasonably translated into somatotype then new avenues of research would be opened. Since height and weight (the components of BMI) data are collected in many clinical and research contexts, it would now be possible to expand somatotype research greatly. The purpose of this paper is to test how well BMI captures somatotype using an archival sample collected by Sheldon (1942) that includes somatotype, height, and weight, for 200 young adult men.
1. Method 1.1. Sample In 1942, Sheldon, the inventor of somatotyping, published a study of 200 White male university students and graduates. Ages ranged from 17 to 31, with a mean of 23.3. In an appendix to his study Sheldon included somatotype ratings, height in inches, and weight in pounds for all 200 participants. 1.2. Analysis The data were entered into SPSS. BMI was calculated using the standard formula; (weight in pounds × 703)/(height in inches squared) (Oria et al., 2005). Using BMI scores individuals were assigned to a somatotype category based on the criteria suggested by Maddan et al. (2008). One difficulty in evaluating somatotype classification by BMI is that this method assigns all individuals to a single discrete somatotype; endomorph, mesomorph, or ectomorphs, while in Sheldon’s system individuals receive ratings on each scale. Sheldon did, however, create a graphic system for plotting the relationship between somatotypes called a somatochart. According to Parnell (1958) position in a somatochart allows us to assign most individuals to one of the three categories: “At the center will be found somatotype 444 with the most balanced body proportions and near to average measurements. Endomorphs (fat persons) lie southwest of this point, muscular mesomorphs lie to the north, and the linear ectomorphs to the southeast (p. 2).”
Using position in the somatochart it was possible to assign 173 individuals to a discrete somatotype category. The remaining 27 fell exactly on a cusp between categories and could not be assigned.
392
J.E.C. Genovese / The Social Science Journal 46 (2009) 390–393
Table 1 Somatotype categorization. Sheldon somatotype
Somatotype assigned by Maddan et al. (2008) BMI method Endomorphs
Endomorphs Mesomorphs Ectomorphs Cusp
10 5
Totals
15
Mesomorphs 24 75 34 27 160
Ectomorphs
25 25
Totals 34 80 59 27 200
Note. Correct classifications are in bold.
2. Results Table 1 compares the somatotypes assigned by somatochart and by BMI. Since 27 individuals could not be classified 86.5% is an upper limit for accurate classification. The BMI method was only able to correctly classify 110 individuals, 55% of the sample. The BMI method over identified mesomorphs, giving this label to 160 individuals, 80% of the sample.
3. Discussion While BMI has been widely used as in an indicator of obesity, there has been a growing awareness that it is inadequate for this purpose (Cawly & Burkhauser, 2006). BMI cannot distinguish between individuals who have large bodies because of increased muscle mass or increased fat. Thus, it is not surprising that BMI poorly distinguishes between somatotypes. Maddan et al. (2008) are to be commended for identifying the difficulties with traditional somatotyping procedures and searching for a reasonable proxy. Unfortunately, BMI appears to be a poor substitute. However, it is quite possible that some other measure may allow us to capture body build. In recent years a number of alternatives and supplements to BMI have been proposed (Cawly & Burkhauser, 2006); including percentage of body fat, waist to hip ratio, and waist circumference.
References Cawly, J., & Burkhauser, R. V. (2006). Beyond BMI: The value of more accurate measures of fatness and obesity in social science research (Working Paper No. 12291). Cambridge, MA: National Bureau of Economic Research. Genovese, J. E. C. (2008). Physique correlates with reproductive success in an archival sample of delinquent youth. Evolutionary Psychology, 6, 369–385. Maddan, S., Walker, J. T., & Miller, J. M. (2008). Does size really matter? A reexamination of Sheldon’s somatotypes and criminal behavior. The Social Sciences Journal, 45, 330–344. Oria, H. E., et al. (2005). Guidelines for weight calculations and follow-up in bariatric surgery. Surgery for Obesity and Related Diseases, 1, 67–68.
J.E.C. Genovese / The Social Science Journal 46 (2009) 390–393
393
Parnell, R. W. (1958). Behaviour and physique. London: Edward Arnold Publisher Ltd. Sheldon, W. H. (1942). The varieties of temperament: A psychology of constitutional differences (with S.S. Stevens). New York: Harper and Row Publishers. Singh, S. P. (2007). Somatotype and disease—A review. The Anthropologist: International Journal of Contemporary and Applied Studies of Man, 3, 251–261 [special issue].