Oh a little controversial topic! – let’s take a look at what BMI is and how the measure works across a population range.
Where did it come from?
Adolphe Quetelet, a mathematician created the formula in the mid 1800’s, yep its that old and wasn’t created to medically measure the population, rather as a measure of the ‘average man’.
In 1972, The Journal of Chronic Diseases published a paper by Ancel Keys and others, indicated that the measure, now referred to as Body Mass Index (BMI) “If not fully satisfactory, at least as good as any other relative weight index as an indicator of relative obesity”
What did this mean? It worked for general populations, but not for individuals.
So why do we still use it then? – great question!
Because it’s generally easy to use, has good foot hold across the population and has been extended to encompass some of the short comings associated with it.
There are many easy ways to pick fault within it, these are largely recognised by the medical industry within its current usage.
Let’s take a look at some of the ways BMI can mis-represent individuals:
Ethnicity
A person’s ethnicity can have an affect on there storage and distribution of both visceral and subcutaneous fat, this requires downward adjustment of BMI bandings by as much as 20% (25 kg/m2 vs 19.2 kg/m2) from the original calculations, whilst this is largely catered for in more modern calculators, it can still produce erroneous readings.
Make-up
The make of a persons body can (with the same overall mass) mislead the results, two individuals with the same weight yet different makeup (body fat vs muscle mass) would return the same BMI figure.
Ratio’s
BMI fails to take into account newer and well tested metrics, whilst utilising height, it ignores waist size, this has been extensively researched and has proven to be a more reliable predictor of cardiovascular disease and type 2 diabetes.
The interesting parts of these are that for the more sedentary individual, the BMI does work, for the less sedentary the figure is unfairly adjusted upward into a category that would make them look less healthy.
Returning to the original question, is BMI a good indicator of health, maybe!
It works for a large proportion of the population, this is probably why, along with its common understanding within the sam population that is sees continued use.
There are of course some more cynical views on this, such as it being used to remove options for certain groups and to continue to keep premiums (in the private sector) higher for profit.
Whether this is true or not doesn’t change the fact that it does hold water for the larger majority of individuals, when the above is taken into account.
It gives an individual a good starting point, if they are starting from a more sedentary position, as we start to train, gain muscle and undertake exercise, it can become less useful.
This is where other measurements, such as height vs waist ratio, bone, body fat and muscle become more appropriate.
Whenever we cover a topic like this, we have views on both sides of the fence, and specific points can be right for each, looking for an exact answer can depend on the metrics defined.
The answer ‘it depends’ is usually where we end up, not because we want to appease all, but rather that we work with individuals that both could benefit from it and those we know would get an erroneous result from – giving us a conflict, but also an objective viewpoint again based on what is going to work best for the given individual.
Would you like to know more about how BMI and yourself? – Chat to one of the team here at SF info@spikefitness.co.uk or 07597215652.