<P> Waist circumference is a good indicator of visceral fat, which poses more health risks than fat elsewhere . According to the U.S. National Institutes of Health (NIH), waist circumference in excess of 102 centimetres (40 in) for men and 88 centimetres (35 in) for (non-pregnant) women, is considered to imply a high risk for type 2 diabetes, dyslipidemia, hypertension, and CVD . Waist circumference can be a better indicator of obesity - related disease risk than BMI . For example, this is the case in populations of Asian descent and older people . 94 centimetres (37 in) for men and 80 centimetres (31 in) for women has been stated to pose "higher risk", with the NIH figures "even higher". </P> <P> Waist - to - hip circumference ratio has also been used, but has been found to be no better than waist circumference alone, and more complicated to measure . </P> <P> A related indicator is waist circumference divided by height . The values indicating increased risk are: greater than 0.5 for people under 40 year of age, 0.5 to 0.6 for people aged 40--50, and greater than 0.6 for people over 50 years of age . </P> <P> The Surface - based Body Shape Index (SBSI) is far more rigorous and is based upon four key measurements: the body surface area, vertical trunk circumference, waist circumference and height . Data on 11,808 subjects from the National Health and Human Nutrition Examination Surveys (NHANES) 1999--2004, showed that SBSI outperformed BMI, waist circumference, and A Body Shape Index (ABSI), an alternative to BMI . </P>

What do you mean by body mass index explain the procedure of calculation of bmi