A BMI is calculated by dividing the ‘mass’ of a body (its weight in kg) by the square root of its height (in metres), the resultant figure is expressed as a unit of kg/m2 though usually the number is taken as a BMI ‘score’ without any reference to the units.
In the US and countries which don’t use metric measures, the same index is calculated using lbs and inches and then multiplying the result by 703 to give a directly comparable ‘score’.
This rather elaborate but elegant benchmark for body ‘thickness’ was actually developed in the mid 1800’s by Adolphe Quetlet, a Belgian mathematician who pioneered the introduction of statistics into the new social sciences and was intended to identify the ‘average’ body type of any particular group.
It wasn’t until the early 1970’s that the measure was applied to individuals as a way of benchmarking their size against the ‘norm’.
It was seen as a much easier way to classify an individual than actually measuring body fat, and conveniently took the offensive words ‘fatness, thickness, portly, etc’ out of the consulting room.
Patients were no longer fat; they just had a high BMI.
The actual definitions of ‘overweight’ and obese may vary slightly from country to country but are now roughly in line, especially since the USA reduced its ‘overweight’ and ‘obesity’ thresholds in 1994 to match WHO recommendations.
29 million Americans were instantly re-categorised from healthy to overweight, which must have been something of a shock.
Essentially, a healthy BMI lies between 18.5 and 25, anything between 25 and 30 is overweight and a BMI of more than 30 is classified as obese.
Incidentally, a BMI of less than 18.5 is regarded as a possible indicator of malnutrition or eating disorder and should be taken equally seriously.
This BMI has grown to become the fixation of most public health planners and practising clinicians, indicating as it does the likelihood of other health issues in the future.
Which is why the European Association for the Study of Obesity (EASO), supported with sponsorship from medical technology giant Medtronic, decided to see if public perceptions in Europe matched the understanding of health professionals with regard to obesity.
From the medical community’s perspective, especially seen through the prism of EASO, the level of obesity in European populations is already at crisis point and becoming worse.
They estimate that, if current trends continue, the proportion of overweight or obese Europeans will, by 2030, range from 44% of the Belgian population to 90% of the Irish.
As apocalyptic and hyperbolic as that may sound, it is interesting to compare how the various nationalities view this very genuine issue which faces the whole of the developed world.
What emerges is a mixture of denial and intolerance, a misunderstanding of the scale of the problem and a willingness to scapegoat those who – as most see it – have brought this on themselves.
Less than half of the survey’s respondents were ‘happy’ with their weight while 20% admitted to taking no action to control it and even fewer monitored their calorie intake.
Over a third of respondents who were actually obese underestimated their own weight, the most accurate being the Italian group, where only 18% underestimated.
Danes and Germans were the most inaccurate, where 49% and 45% respectively undercut their personal weight below the level of obesity, as did 36% of the British group.
Overall, three out of four of the subjects surveyed who were medically obese described themselves as either ‘healthy’ or merely ‘overweight’.
When it came to their perceptions of fellow citizens there was a trend across all the groups to grossly underestimate the proportion of people who were overweight while slightly overestimating the proportion of obese compatriots.
The British managed to underestimate both, the average response suggesting that only 32% of Britons were overweight when the actual figure is 41% and that 22% were obese when the actual figure is 24%
At the same time only 46% of respondents identified obesity as a disease while 79% described it as a lifestyle choice, the figure for this was much higher in the UK where 92% believed obesity is a choice, only 25% thought there were genetic, psychological or physiological factors involved.
The UK topped the league of those who saw obesity as a grave danger, 51% of British respondents agreed that it was a greater health threat than smoking.
Only 38% of Britons recognised that stress caused overeating, in France this figure was 55%.
In another table topping performance 68% of the British contingent thought that obesity sufferers should pay for any medical procedure they received.
So where does that leave us?
I think that obesity has become so demonised and vilified in the British press that we are now less likely than ever to face it and admit when we have a problem.
This self-awareness is made even less likely while obesity is regarded as a sign of weakness or lack of will, less still if it is seen as the lifestyle choice of the lazy and feckless.
‘I am out of condition, you are fat’ seems to be the order of the day.
The corrosive pattern of private self-denial and public blame and shame can only make it harder for the health professionals to get their messages through and identify those who need support and treatment before obesity turns into something even more destructive.
It’s a concern to us all, let’s not make it any harder by driving it underground.
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