Most of us are familiar with the term “BMI.” The concept actually isn’t new. In fact, a similar index was developed by a Belgian scientist back in 1832, with the term “body mass index” appearing in 1972.

What does BMI stand for? It stands for body mass index, which is a basic “surrogate” measure of body fat based on a person’s weight and height. How to measure BMI is pretty quick and easy by using simple charts that cross-reference those two figures.

Although it’s not a direct measurement of body fat, it appears to line up well with more complicated and expensive procedures. Examples of those more involved procedures include underwater weighing, dual energy x-ray absorption and bioelectrical impedance.

Limitations of BMI Numbers

BMI is used as a tool in determining whether an individual is overweight or obese, conditions that are on the rise in U.S. and worldwide. It is not considered a diagnostic indicator, and a further assessment may include factors like family history, diet, exercise and other screening categories.

But the bottom line is that BMI is an indicator of current or approaching issues related to weight gain. BMI ranges include: less than 18.5, underweight; 18.5-24.9, normal; 25-29.9 overweight; and over 30, obese. So if you have a BMI over 30, it’s probably time to take action and get your body back into a healthy BMI range.

With extra weight can come more stress on the heart, increased blood pressure, higher cholesterol and the potential for diabetes, liver disease, arthritis and sleep apnea. One estimate puts the number of deaths annually in the U.S. due to obesity at some 365,000. Maintaining healthy weight can also have positive lifestyle effects from reduced joint and muscle pain to more energy and better sleep.

BMI is good to consider when taking a proactive approach to managing your weight and the risks that are presented by packing on too many pounds than is healthy for you. Keep in mind that it doesn’t take into account factors like age, muscle vs. fat weight, your natural body frame type or ethnic background.

Going Beyond Simple BMI

A way to take BMI a step further is by determining your body fat percentage. This can be done at home in two ways. One is to use a caliper to pinch and measure the fat layer that resides under your skin, then refer to body fat percentage formulas or calculators. The other is to purchase a bathroom scale with a body fat measurement function. It’s done via a small electrical impulse.

Another potentially important factor to consider is the “apple vs. pear” body shape. Not only the sum total, but the distribution of one’s weight can indicate health risk. The key indicator is how much of relative body weight is distributed around the midsection – the apples. Simply measure your waist at the top of your hip bones. Data has shown that a waist circumference of about 35 inches for women and 40 inches for men may be cause for concern.

BMI Is Just a Starting Point

So, is BMI important? Yes, it can be, as a single statistic. But keep in mind that BMI is not an indicator of overall health. A BMI that seems too high or too low can happen with healthy people. And others, like smokers or with a family history of heart disease, may have a normal BMI.

Nothing can take the place of regular physical and wellness examinations by your physician to evaluate your overall health profile. Moreover, lifestyle changes in terms of diet, exercise and adequate sleep can help avoid or mitigate problems.

It’s great to periodically check your BMI. But, as Clint Eastwood say, know its limitations.