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What Is The Body Mass Index Formula?

Aug 31, 2009

The body mass index formula calculates what is considered underweight, healthy, overweight, and obese based on your height and weight measurements. The simple, easy-to-calculate formula can be very helpful in identifying risk for diseases and conditions related to being underweight and obese when used correctly.

Defining what is overweight can be a sensitive topic and the BMI formula has its drawbacks. It can potentially misclassify people because it does not take into account anything other than weight and height. However, it is also commonly used and very effective in identifying risk factors for many diseases and conditions that are generally associated with excess body weight such as type 2 diabetes, coronary heart disease, and high blood pressure.

How Does the Formula Work?

The BMI formula calculates whether or not you are at a healthy weight for your height. It does not take any special consideration for your overall body composition or age, and therefore is not completely accurate. Some people that may have particularly skewed BMIs are:

  • Competitive athletes
  • Body builders
  • Pregnant or nursing women
  • Frail or elderly people

How to Calculate Your BMI?

Calculating your BMI is rather simple, making it the leading reason that the formula is so commonly used. There are many online calculators that can be used, or you can follow the following equation:

BMI = weight (pounds) x 703

               Height2 (inches2)

What Does The Result Mean?

An optimal BMI is considered anywhere between 18.5 and 25. If you have a BMI lower than 18.5, you are considered by the BMI calculation to be underweight. Anything over 25 is considered overweight, anything over 30 is considered obese, and over 40 is considered morbidly obese.

How is this Information Used?

BMIs have a number of applications. The main one is to collect statistical information on the obesity of the population. This information is used for countless studies throughout the world to determine how obesity affects people’s lives.

The information is also very helpful in the medical profession to identify patients that may have increased risks for such weight-related diseases as high blood pressure, type 2 diabetes, and coronary heart disease. Additionally, this information is commonly used by insurance underwriters to determine insurance rates for members, as it is proven that people who are obese suffer from greater health problems than those that are within the normal weight range.

Though this formula does provide a starting point for determining your health, everyone is different and these numbers may not accurately reflect your body’s unique composition. Talk to your doctor to determine if you are in a healthy range, and if not, work with your doctor to develop a plan that is right for you to make some changes to your lifestyle. This could greatly improve your health.

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