What is body mass index or BMI?
The body mass index otherwise known as BMI, is a simple calculation using a person’s height and weight. The result typically in the range of 15 to 60 is known as the BMI or body mass index score. Most health organizations put a healthy BMI score between 18.5 and 25.0. Some people refer to this as a normal BMI.
Because it measures excess weight and not actually excess fat, BMI is considered a surrogate measure of body fat. However, studies show strong correlations between BMI measurements and the results of more direct body fat measures. If you are concerned about your weight or body size, calculating your body mass index is a good place to start before heading to the doctor’s office. BMI can predict future weight-related issues including disease and even death, so it is a very helpful tool in screening for health risks and obesity.
Individuals with a body mass index under 18.5 are considered underweight. A BMI this low can indicate an undernourished individual. Your body needs “meat on your bones”, to be able store energy.
If your BMI is between 25.0 and 29.9 you are considered overweight. Many athletes will fall into this range, and while it is true that their conditioning is high, there is still a lot of “mass” for the body to pump blood and provide oxygen to.
A body mass index greater or equal 30 is described as obese. Your body is under greater daily strain simply because of your weight. Your organs are not designed to work this extra hard, on a sustained daily basis. Your joints, especially the feet, ankles, knees and hips are put under much more stress.
Though body mass index is a simple, easy, and inexpensive way to measure your body size and fat content, it is not perfect. Because it does not directly measure your body fat, the results will not be as accurate as other measures. While body mass index should not be used as a diagnostic tool, it is a good screening tool for identifying potential weight problems in adults.
Your body mass index is not about what weight you look the best at, it is what weight are you the healthiest with the energy stores your body needs, and the amount of tissue your organs must provide blood and oxygen to.
BMI is a useful measure of overweight and obesity. BMI is an estimate of body fat and a good gauge of your risk for diseases that can occur with more body fat. The higher your BMI, the higher your risk for certain diseases such as heart disease, high blood pressure, type 2 diabetes, gallstones, breathing problems (especially when sleeping), and certain cancers. BMI can be used for most men and women. It may underestimate body fat in older persons and others who have lost muscle.
Small weight loss for those with a BMI over 25 (between 5 and 10 percent of your current weight) will help lower your risk of developing diseases associated with obesity.
If you are a woman who is pregnant, body mass index is not a good measurement to use. Always listen to your health care provider concerning weight gain during pregnancy. Pregnant women need to gain extra weight for the health of themselves and their unborn baby. While your BMI measurement would show that you have excess weight when pregnant and may push you into the overweight or obese ranges, you are probably still healthy. Consult your doctor if you have any concerns about gaining too much weight during pregnancy.
Use our plan for weight loss section of our blog to find out ways to lower your bmi.
Calculator Source: Adolphe Quetelet (1796-1874)”the average man and indices of obesity”. Nephrology Dialysis Transplantation 23 (1): 47-51
If you place 1 pound of muscle next to 1 pound of fat, the muscle would be 22% smaller in size.