Before we consider assessment of obesity, it will be useful to first, look at body composition as under:
(1) The active mass (muscle, liver, heart etc.)
(2) The fatty mass (fat)
(3) The extracellular fluid (blood, lymph etc.)
(4) The connective tissue (skin, bones, connective tissue)
Structurally speaking, the state of obesity is characterized by an increase in the fatty mass at the expense of the other parts of the body. The water content of the body is never increase in case of obesity.
Although obesity can easily be identified at first sight, a precise assessment requires measurements and reference standards. The most widely used criteria are:
Body weight
Body weight, though not an accurate measure of excess fat, is a widely used index. In epidemiological studies it is conventional to accept +2 SD (standard deviations) from the median weight for height as a cut-off point for obesity.
For adults, some people calculate various other indications such as:
(1) Body mass index (BMI or Quetelet’s index)
BMI = weight in kilogram divided by height in meter square (m2)
(2) Ponderal index
Ponderal index = height in cm divided by cube root of body weight in kg
(3) Broca index
Broca index = Height in centimeters minus 100
For example, if a person’s height is 160cm,
His ideal weight is (160-100) (cm) = 60kg
(4) Loreniz’s formula
Loreniz’s formula = height in cm minus 100- (height in cm -150) divided by (2 for women or 4 for men)
(5) Corpulence index = actual weight divided by desirable weight.
The body mass index (BMI) and the Broca index are used more commonly. A recent FAO/WHO Report gives the much needed reference table for body mass index which can be used internationally as reference standards for assessing the prevalence of obesity in a community.
