Body mass index
A body mass index is a mathematical formula that determines the health effects of one's body weight. It is also referred to as a BMI.
Traditionally designed for public health studies, the BMI is calculated by the weight over the height squared.
It is used to offer an estimate of obesity, but only in the broadest overview of correlation between weight and height. It is used for this purpose because height and weight are typically included in sociological studies, whereas more precise indicators are often left out of studies.
The body mass index was developed by Adolphe Quetelet when he was working out a system of social physics from 1830 to 1850. It is also, therefore, known as the Quetelet Index.
BMI is typically used to calculate overweight and obesity in several countries and has been used since the 1980s. The World Health Organization uses it to measure its obesity statistics.
The BMI became familiar to the general public in the 1990s and 2000s by means of public health projects that encourage fitness and healthful eating. Public health campaigns promote body mass index as a rule of thumb method of calculating optimum weight.
There are more effective means of measuring overweight and obesity. Other popular methods include the skinfold tense (where the thickness of the fat layer is measured) and the water displacement test.
Guidelines for health
The health rating for human bodies ranges from near starvation to morbidly obese. In general, a BMI ranked under 18.5 is considered underweight (and a possible indicator of malnutrition, an eating disorder or another health problem). A BMI greater than 25 is considered overweight. A BMI over 30 is considered obese.
These boundaries apply for adults older than 20 years of age.