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[Click to calculate your BMI right now]
Body mass index (or BMI) is defined as the person’s body weight divided
by the square of his or her height. Body mass index may be calculated using the formula below:
 
Scroll down to the bottom of this page to calculate your body mass index
Body Mass Index (BMI) is one of the ways to determine when extra fat accumulation
translates into health risks. Body mass index is a measure which takes into account a person’s
weight and height to gauge total body fat in adults. The higher the body mass index, the greater the
risk of developing additional health problems. The following chart describes the various categories of
obesity based on body mass index:
- BMI = 19 - 24 Desirable
- BMI = 25 - 30 Overweight
- BMI = 31 - 35 Obese, category 1
- BMI = 36 - 40 Obese, category 2
- BMI > 40 Severe obesity
Heart disease, diabetes and high
blood pressure are all linked to being overweight and obese.
As the body mass index and obesity increase, so does the mortality risk. The
following figure gives the relationship between body mass index and mortality risk
(Image courtesy: Wadsworth
Publishing Company, 1999)
It is clear from the figure above that the healthy
range of body mass index where the mortality is lowest lies somewhere between 20
and 27.
But a word of caution! Body mass index does not
totally and exclusively describe the health status of a person. The concept of
body mass index does not apply at all to athletes and body builders, because,
body mass index does not take into account the body composition. Athletes and
body builders generally have more muscle and bone mass than fat as compared to
general people. To give an example, consider a body builder whose weight is 120
Kg. and whose height is 173 cm. As per the formula given above his body mass
index works out to be about 40 which falls in the category of being severely
obese. But this is far from truth because the body builder in question has very
low fat percentage as compared to a lay person whose body mass index is 40.
The BMI or body mass index is the current standard for
healthcare professionals to evaluate body fat. Although BMI may be misleading
for certain populations such as athletes, body builders, the elderly, pregnant
women, and shorter people, the BMI is still a useful tool for most people.
Experts now believe that the waist-to-hip ratio is a
better index to evaluate health risks associated with fat on the belly. Men
whose waists are larger (more than about 40 inches for the westerners and 35
inches for Asians) are described as being apple-shaped. (The respective
measurements for women are 35 inches for westerners and 32 inches for asians)
Apple shape bears more risk for health including diabetes, heart disease, high
blood pressure. In fact the apple shape is one of the major characteristics of
the metabolic syndrome X
In a recent study by Salim Yusuf and others of the
Population Health Research Institute of McMaster University and Hamilton Health
Sciences at Canada has demonstrated that waist-to-hip ratio, (and not the BMI)
more accurately demonstrated to be a predictor of heart attack.
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