Body mass index, or BMI, is a measurement used by health organizations and practitioners to determine whether a person falls within a healthy weight range. To determine your BMI, divide your weight in kilograms by your height in meters squared. According to the Centers for Disease Control and Prevention, BMI can be a reliable indicator of obesity or fatness for many people, but it does not measure body fat directly.
Significance
The formula to figure out BMI was devised by Belgian statistician Adolphe Quetelet. Doctors use BMI to determine if a patient is overweight and obese and thus at a greater risk of developing certain disease. Some insurance companies use BMI as a determinate as to whether a patient needs weight loss surgery. Police and fire departments use BMI to determine whether their employees are fit to serve. Life and health insurance companies may use BMI to determine your eligibility.
Healthy Range
According to the BMI standard, a person with a BMI over 25 is overweight. When your BMI exceeds 30, you are obese. Those who fall under 18.5 are underweight. Anyone falling between 18.5 and 24.9 is considered "normal." BMI makes no distinction for age or gender.
Positives
One of the reasons BMI is a popular standard is because the equation is simple. Calculating BMI requires no invasive testing. Alternative measures of body fatness such as DXA scans, hydrostatic weighing, skin caliper testing and bioelectrical impedance require specially trained technicians and equipment.
Problems
BMI measurements are often flat-out wrong when it comes to women and athletes. According to mayoclinic.com, because BMI does not take into account differences in body fat levels between the genders, BMI measurements often mis-categorize women who are actually obese as being of normal weight. At the other extreme, BMI calculations often classify athletes as being overweight or obese, when they really have a high amount of lean muscle mass and are not at risk of developing health problems due to obesity.
Considerations
In addition to mis-classifying certain populations, BMI fails to identify other weight-related risk factors for chronic health problems. BMI cannot evaluate where a person stores body fat. People who store excess fat at their midsection are at risk of developing multiple health problems---including diabetes, cardiovascular disease and dementia notes Rachel Whitmer, a researcher at Kaiser Permanente Division of Research in Oakland in March 2008 issue of USA Today. Although a person falls into a healthy range on BMI, he may have a waist circumference that endangers his health. If medical professionals do not take this into account, they may fail to intervene in a patient's health before the onset of illness.
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