|
The body mass index (BMI), or Quetelet index, is a heuristic proxy for human body fat based on an individual's weight and height. BMI does not actually measure the percentage of body fat. It was invented between 1830 and 1850 by the Belgian polymath Adolphe Quetelet during the course of developing "social physics". Body mass index is defined as the individual's body weight divided by the square of his or her height. The formulae universally used in medicine produce a unit of measure of kg/m2. BMI can also be determined using a BMI chart, which displays BMI as a function of weight (horizontal axis) and height (vertical axis) using contour lines for different values of BMI or colors for different BMI categories.
A frequent use of the BMI is to assess how much an individual's body weight departs from what is normal or desirable for a person of his or her height. The weight excess or deficiency may, in part, be accounted for by body fat (adipose tissue) although other factors such as muscularity also affect BMI significantly (see discussion below and overweight). The WHO[9] regard a BMI of less than 18.5 as underweight and may indicate malnutrition, an eating disorder, or other health problems, while a BMI greater than 25 is considered overweight and above 30 is considered obese. These ranges of BMI values are valid only as statistical categories
| Category | BMI range – kg/m2 | BMI Prime | Mass (weight) of a 1.8 metres (5 ft 11 in) person with this BMI. |
| Severely underweight |
less than 16.0 |
less than 0.66 |
less than 51.8 kilograms (8.16 st; 114 lb) |
| Underweight |
from 16.0 to 18.5 |
from 0.66 to 0.73 |
between 51.8 and 59.9 kilograms (8.16 and 9.43 st; 114 and 132 lb) |
| Normal |
from 18.5 to 25 |
from 0.74 to 0.99 |
between 59.9 and 81.0 kilograms (9.43 and 12.76 st; 132 and 179 lb) |
| Overweight |
from 25 to 30 |
from 1.0 to 1.19 |
between 81.0 and 97.2 kilograms (12.76 and 15.31 st; 179 and 214 lb) |
| Obese Class I |
from 30 to 35 |
from 1.2 to 1.39 |
between 97.2 and 113.4 kilograms (15.31 and 17.86 st; 214 and 250 lb) |
| Obese Class II |
from 35 to 40 |
from 1.4 to 1.59 |
between 113.4 and 129.6 kilograms (17.86 and 20.41 st; 250 and 286 lb) |
| Obese Class III |
over 40 |
over 1.6 |
from 129.6 kilograms (20.41 st; 286 lb) |
The U.S. National Health and Nutrition Examination Survey of 1994 indicated that 59% of American men and 49% of women had BMIs over 25. Morbid obesity—a BMI of 40 or more—was found in 2% of the men and 4% of the women. The newest survey in 2007 indicates a continuation of the increase in BMI: 63% of Americans are overweight or obese, with 26% now in the obese category (a BMI of 30 or more). There are differing opinions on the threshold for being underweight in females; doctors quote anything from 18.5 to 20 as being the lowest weight, the most frequently stated being 19. A BMI nearing 15 is usually used as an indicator for starvation and the health risks involved, with a BMI <17.5 being an informal criterion for the diagnosis of anorexia nervosa.
Singapore
In Singapore, the BMI cut-off figures were revised in 2005 with an emphasis on health risks instead of weight. Adults whose BMI is between 18.5 and 22.9 have a low risk of developing heart disease and other health problems such as diabetes. Those with a BMI between 23 and 27.4 are at moderate risk while those with a BMI of 27.5 and above are at high risk of heart disease and other types of health problems.
| Category | BMI range – kg/m2 |
| Emaciation |
14.9 or less |
| Underweight |
from 15 to 18.4 |
| Normal |
from 18.5 to 22.9 |
| Overweight |
from 23 to 27.5 |
| Obese |
from 27.6 to 40 |
| Morbidly Obese |
greater than 40 |
(wikipedia)
|
