The body mass index (BMI) is frequently used by the medical establishment to assess cardiovascular disease risk because it is unintrusive and quick. However, studies show that the waist-to-hip ratio is a more accurate predictor of cardiovascular disease risk, despite it intrusive nature and the difficulty encountered in locating correct measuring points. To assess the waist-to-hip ratio, first the waist circumference is taken by wrapping the a tape measure loosely around the narrowest part of the torso, as viewed from the front. Secondly the tape is loosely placed around the widest part of the hips, that includes the protuding buttock, as viewed from the side. The measurement of the waist is divided by the measurement of the hip (in cm) to give the waist-to-hip ratio. A value of over 0.9 and 0.8 is associated with an increased risk of cardiovascular disease in men and women, respectively. The wait-to-hip ratio is a good predictor of cardiovascular risk because it reflects the presence of abdominal fat, a marker of the metabolic syndrome.
The body mass index is actually a poor marker for disease because it does not take into account muscle mass. For example, athletes involved in strength and power sports can often have body mass indexes above 30 kg/m2. This would classify them as being obese, but their low body fat percentage and high amounts of muscle mass put them at low risk of cardiovascular disease. If the same athlete were to have their waist-to-hip ratio taken, a more accurate representation of their cardiovascular risk would be obtained. Likewise, some individuals can have low body mass indexes, but still suffer from metabolic syndrome and therefore be at high risk of cardiovascular disease. A waist-to-hip ratio measurement on such individuals would highlight the presence of abdominal fat tissue and more correctly ascribe their true cardiovascular risk. Waist-to-hip ratio has increasingly been utilised in the research setting but is unlikely to be used as a regular medical tool because of the extra effort a doctor would have to go to to accurately take the measurements.
RdB waist-to-hip ratio
Dobbelsteyn, C. J., Joffres, M. R., Maclean, D. R. and Flowerdrew, G. 2001. A comparative evaluation of waist circumference, waist-to-hip ratio and body mass index as indicators of cardiovascular risk factors. The Canadian Heart Study. International Journal of Obesity. 25(5): 652-661
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