Living Well in Yalobusha County

Understanding the Body Mass Index

A search study listed Mississippi as the number one state when it comes to obesity.  According to The Trust for America’s Health, Mississippi is the first state where more than 30 percent of the adults are considered obese.  From a health standpoint, obesity is related to higher rates of many illnesses, including many chronic illnesses, such as cardiovascular disease, certain cancers, and diabetes.

You may have asked what defines obesity in adults.  Primarily, to determine obesity, we use an equation called the Body Mass Index or BMI.  Body Mass Index is simply a measure of an individual’s weight in relation to their height.  Depending on one’s BMI, the individual would be placed in a certain category, ranging from underweight to obese.  BMI is preferred in large population studies, because it is easy to calculate.  To determine a BMI you simply need to have an individual’s height and weight.  Often times this information can be self-reported by individuals and the information can be gathered without researchers having to actually measure the individuals.  Collection methods such as telephone surveys or websites can be used to gather the information, with little or no cost.

So, how do you calculate Body Mass Index.  Well, the actual equation is an individual’s weight in kilograms (kg), divided by the persons height in meters squared (m2). Since we don’t use the metric system very much in the United States, the formula has been converted to use standard U.S. measurements such as pounds (lb) and inches (in). To calculate your BMI using pounds and inches follow these steps: (1) Multiply your weight in pounds by 703. (2) Divide that answer by your height in inches and (3) Divide your next answer by your height in inches again.  This will give you your BMI.  For example let’s say we want to know the BMI for a man who is 180 lbs and 6 feet (72 inches) tall.

180 x 703 = 126,540 / 72  = 1,757.50 / 72 = 24.4 or BMI = 24

Of course, if math is not your strongest area, there are plenty of BMI calculators available on the internet that you can use to help you determine your BMI.

Now, that you have your BMI, you may want to know what this number means.  BMI ranges are determined based on their relationship to weight-related problems.  We primarily look at 4 different BMI ranges, underweight, appropriate weight, overweight, and obese:

Underweight = BMI less than 18.5: should be addressed with health care professional.

Appropriate = BMI 18.5-24.9: not a risk factor for weight-related health problems

Overweight = BMI 25-29.9: some increased risk for weight-related health problems

Obese = BMI 30 or over: significant increased risk for weight-related problems  

It is also important to note there are pros and cons when using BMI.  As mentioned earlier, it is an easy and simple method to gather data simply by asking people their weight and height.  Self-reporting weights and heights saves both time and money.  However, when data is self-reported, people may misrepresent their height and weight.  So, the BMI for an individual may not be completely accurate.  

Also, BMI does not distinguish between male and females or individual body types.  BMI is considered a measure of body weight and not a measure of body fat.  A person’s weight can fall into the appropriate weight range and have a higher than beneficial percentage of body fat. Body fat is essentially the percentage of body fat one has compared to their overall body weight.  Realize that body weight not only includes fat, but also your blood, muscles, bones and other tissues. Instruments like skinfold calipers and other more accurate methods can determine percent body fat, but there is increased time and cost when compared to BMI.

Body Mass Index is a good initial indicator and often times can help begin the dialogue between you and your health care provider. By knowing your BMI you can help  determine your risk regarding weight-related problems.  However, it is only one piece of the health puzzle.  By knowing additional information, such as your blood pressure, cholesterol, and blood sugar levels, you will have a more accurate picture of your current health status.  It is important that you work with your health care provider to check these and other levels on a regular basis to determine if they are appropriate for you.  If they are not, your health care provider can work with you to make changes and reduce your risk of health problems in the future. 

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