Body Mass Index Define Plus 1 Simple BMI Calculator


Body Mass Index Define

Body Mass Index (BMI) measures lean body mass based on a calculation involving height and weight. The World Health Organization (WHO) set the criteria and categories for BMI, also known as the Quetelet index.

BMI is an indicator of body fat

and potential health risk and an indirect indicator of obesity. Other indirect indicators of obesity include waist circumference and the ratio of waist to hips.

Knowing your BMI allows you to compare your BMI measurement to standard weight ranges to see if your body weight is considered appropriate relative to your height.

Body Mass Index Define


Though BMI is often used to assess individuals, it was not originally intended to be used for this purpose.

BMI was created to evaluate large groups of people for weight issues, such as obesity, in academic studies.

Such studies often consider the relationship between BMI levels and health conditions. BMI’s uses also include creating body composition estimates, reference standards, and baseline data for studies as an academic tool.


Academics also use BMI to observe trends in certain populations and determine the risks for certain health outcomes.

BMI is used as a screening tool for weight issues and private health insurance underwriting for individuals.

However, it is not considered to be a diagnostic tool and should be used with other measurements.

Many medical professionals use BMI along with other measurements and tests to make treatment recommendations to their patients.


Body Mass Index Define. To define Body mass index we need to calculate your BMI, you divide your weight in pounds by your height in inches squared and multiply the result by 703.

You can calculate your BMI by dividing your weight in kilograms by your height in meters squared.

BMI calculators are available online in which you enter your height and weight, and the calculation is done for you.

The BMI calculation must be made using your correct height and weight. BMI is often underestimated or overestimated when height or weight is misreported.

Both of these numbers can change with age. Some people cannot stand up straight for an accurate measure of their height due to health issues like disease, weakness, or spine curvatures.


The BMI categories are:

  • underweight
  • normal weight
  • overweight
  • obese
  • severely obese

While all countries use these categories, there is a little variation in what BMI standards fall into each category in some countries.

The differences reflect variations in disease risk among different people groups. In the United States, the BMI standards for adults are:

  • underweight: under 18.5
  • normal: 18.5-24.9
  • overweight: 25 to 29.9
  • obese: 30-40
  • severely obese (more than 100 pounds over ideal weight): over 40

For children, teens, and young adults between the ages of two and 19, BMI is calculated and evaluated differently. Height, weight, age, and sex are included in this BMI calculation.

The resulting BMI figure is considered as a percentile of other people of the same age and sex.

For this BMI calculation, those below the fifth percentile are considered underweight. Those in the 85th and 94th % are considered overweight, and those in the 95th percentile and above are considered obese.


Though BMI has its limitations, it is a good screening tool for determining if you are overweight or obese, as well as an indicator of your risk for obesity-related diseases.

There is also a connection between your BMI and your total fat mass. However, your age, gender, ethnicity, and fitness level should also be considered when you use your BMI to determine your health risk.

If you have a high BMI, you are not necessarily at risk for the health problems associated with being overweight or obese.

For longevity in adults, a BMI between 20.5 and 24.9 is optimal, though people who are moderately overweight may also have an advantage that translates into a longer life.


If you are an adult and your BMI is increasing, it is often associated with chronic diseases like type two diabetes, high blood pressure, coronary artery disease, and high cholesterol.

It is also a good indicator of the potential for sleep apnea, degenerative joint disease, and certain cancers.

An increasing BMI is often linked to depression, low self-esteem, physical disability, social discrimination, and unemployment.

In children, annual BMI increases are most often related to an increase in lean mass, not fat tissue. When young people reach late adolescence, their fat mass begins to affect their BMI numbers.


BMI is considered problematic for certain adults because it only looks at weight and height without context. Therefore, it can be misunderstood or misused.

For example, BMI may not correctly measure obesity in some people. Older adults may have less muscle mass, so their obesity may be underestimated using BMI.

Simultaneously, muscular people, such as athletes, will fall into an obese category even though their heavier weight comes from more muscle mass rather than excess weight.

Similarly, people may have diseases or take medications that cause significant water retention, resulting in incorrect BMI numbers.

Another way that BMI fails to account for differences in people is body fat distribution. Some adults have excess body fat in their abdominal region.

Aging also can change where body fat is carried. While such people’s BMI may be in the normal range, they may actually be obese due to an increase in their waist-to-hip ratio.

Additionally, BMI does not allow for differences in bone structure. Thus, if you have a large frame, your BMI could place you in the overweight or obese category even though you have low body fat.

If you have a small or slender frame, your BMI could be normal even though you have excess body fat, this is one of the reasons why Body Mass Index Define is not always easy to do.

Check Your BMI Index Here



“BMI Calculator.” Mayo Clinic. (accessed October 20, 2018).

“Body Mass Index (BMI).” Centers for Disease Control and Prevention. (accessed October 20, 2018).

“Calculate Your Body Mass Index.” National Heart, Lung, and Blood Institute. (accessed October 20, 2018).