Mathematician Says Current BMI Formula Is Flawed, Rolls Out New One

Short people are fatter than they think, tall ones are thinner than previously assumed

By Laura Sinpetru on January 21st, 2013 13:21 GMT

It has been quite a while since the BMI formula was first used to determine if a person is either underweight or overweight. Needless to say, quite a lot of people ended up changing their diets so as to reach a body mass index their doctor and their self-esteem would have approved of.

However, a mathematician working with the University of Oxford now claims that, as shocking for the health-care industry as this may sound, the BMI formula currently in use is actually a flawed one.

To cut a long story short, it is Nick Trefethen's opinion that the BMI formula most people know and use nowadays fails to properly account for the so-called natural bulk that tall people have.

As a result, those who are relatively short are often told that they are thinner than they really are, and taller individuals are led to believe that they are overweight when it fact they are not.

“BMI divides the weight by too large a number for short people and too small a number for tall people. So short people are misled into thinking that they are thinner than they are, and tall people are misled into thinking they are fatter,” Professor Nick Trefethen commented with respect to the BMI formula currently in use.

“The NHS [the National Health Service in the United Kingdom] relies on the BMI pervasively in all of its public discussions of obesity. We deserve an explanation of what justification they have for using this formula,” he went on to add.

For those unaware, a person's body mass index is – at least for the time being – determined by dividing an individual's weight to the square of his/her weight as measured in meters.

However, as Daily Mail reports, this Oxford researcher is firmly convinced that the weight in kilograms must first be multiplied by 1.3, and only then divided to a person's height to the power of 2.5.

Interestingly enough, this is not the first time when the validity of the current BMI formula is questioned by scientists.

However, up until now, the complaint heard more often has been that BMI cannot serve as an indicator of health simply because it does not differentiate between muscle and fat.
Oxford mathematician says the BMI formula currently in use is flawed
   Oxford mathematician says the BMI formula currently in use is flawed