BMI Test

How does the BMI test work?

The above weight tool can help you determine the ideal weight you should have according to your height. The data required to input is the age in years, gender, weight and height. You are also asked for the country of origin in order to receive some extra information regarding the average BMI in your place of birth or in the country you currently live in. There are two methods of input offered, one in metric and the other one in English for which units feel more comfortable, lbs and feet inches or kg and centimeters.

The BMI test then uses your data in 5 different calculations to determine the ideal weight, through formulas that were released years ago by scientists such as J.D. Robinson and D.R. Miller in 1983, B.J. Devine in 1974, G.J. Hamwi in 1964 and by the Healthy BMI range recommendation made by the World Health Organization (WHO). You are also going to receive the average BMI value in your country, both gender unspecific and gender specific according to the gender you’ve put in the calculation form.

Body Mass Index

The body mass index is a scientifically proved way to assess one’s weight in relation to their height. It can also be defines as the thinness or thickness of the body and has both aesthetic and medical implications. This index is calculated as the weight in kilograms divided by the square of the height in meters.

The value provided by the calculation is then retrieved in some defined weight categories and therefore assesses whether the weight is in the healthy range or somewhere, either below or above the normal. There are also charts in which to quickly retrieve values and these can also be set to retrieve the normal weight range that one should have at a certain weight.

BMI is used to assess health risks and certain medical dosages but does not take in consideration muscular mass so it can sometimes be inaccurate, for instance in the case of athletes or pregnant women. These charts are also defined for adults, as children have their own modified values, according to age and gender.

How to calculate BMI?

The four main body mass index determinant formulas, beside the basic BMI are listed in the table below:

Example results from the BMI testing

A 30 year old male from the US, with a height of 6 feet and 3 inches and a weight of 200 lbs will get the following results from the BMI test:

■ Your BMI is 25;

■ Your BMI category is: Healthy weight - Highest Normal;

■ In United States the average BMI (no gender specific) is: 27.82;

■ In United States the average BMI for male is: 28.64;

■ Your BMI is below the average BMI for male in your country;

■ By using Miller’s formula (1983), your ideal weight is 170.5 lbs;

■ By using Robinson’s formula (1983), your ideal weight is 177.5 lbs;

■ By using Devine’s formula (1974), your ideal weight is 186.3 lbs;

■ By using Hamwi’s formula (1964), your ideal weight is 195.1 lbs;

■ Your recommended weight, based on the healthy BMI recommendation is between 148 lbs and 200 lbs.

BMI Chart

The values obtained through the formula itself or the above weight tool can be found in the ranges of the BMI table based on the International Classification of WHO 2004.

History and implications of the ideal body weight formulas      

The interest for finding a formula that could assess one’s ideal weight dates from back 1871 when surgeon Dr. P.P. Broca published his index: (weight (kg) should equal height(cm) - 100, plus or minus 15% for women or 10% for men.

But then in 1974, Dr. BJ Devine published a formula that converted the one above to pounds and used it for various medical uses, such as dosing the right amount of medicines. This is the formula most used to calculate ideal body weight.

Later in 1983, Dr. JD Robinson and Dr. DM Miller update this equation. In time there were various arguments in regard of the accuracy of these methods, for instance Robinson’s formula was said to perform poorly in the case of tall men. The greatest fault that was found to these equations is that they don’t compensate for age and they also lost some of their applicability in time.

References

1) BMI Classification. (2006) Global Database on Body Mass Index. World Health Organization. 

2) Keys A, Fidanza F, Karvonen MJ, Kimura N, Taylor HL. (1972) Indices of relative weight and obesity. Journal of Chronic Diseases 25 (6–7): 329–43.

3) Walpole SC, Prieto-Merino D, Edwards P, Cleland J, Stevens G, Roberts I et al. (2012) The weight of nations: an estimation of adult human biomass. BMC Public Health 12:439