Saturday, 8 August 2015

"The bigger the number the better" - public health campaigners' cavalier attitude to evidence

An entirely gratuitous picture of cake
I've felt for a long time that single issue campaigners of various kinds - poverty, public health and so forth - have a tendency to choose statistics that maximise the scale of the problem they are campaigning about. From the perspective of campaigning as a business, this makes a lot of sense - if we can demonstrate there are huge numbers 'living in poverty' or some sort of booze or food related crisis then the need for our campaign is all the greater. And we can present the stats to compliant - and media-scared - governments who will carry on providing the funds to pay us so we can carry on campaigning.

This hyping up of a problem does however have a downside - by making the numbers ever larger and the problem greater and greater we feed scepticism and cynicism in the population. If your recommended alcohol limits boil down to a glass of dry sherry twice a week the drinking public (and that's most of us) are going to think something like "that probably a load of nonsense, isn't it", And that public will carry on behaving just as they were before.

So the campaign is sustained because government is given scary figures by the campaigners. And the unwillingness of the population to change its behaviour (because it doesn't believe those scary figures) further reinforces the view of campaigners that "something must be done".

And now we have some evidence to support this theory:

People who think they are overweight or obese are more likely to pile on the pounds than those who are unaware that they may be heavier than doctors would advise, according to research.

The researchers show that telling people that they are fat is unlikely to work because of the stress associated with the stigma of fatness. Yet the obesity industry is utterly predicated on two interpretations of statistics - firstly the conflating of 'overweight and obese' into on number and secondly the narrowing of the definition of 'normal' weight. We're repeatedly told that two thirds of more of adults are 'overweight or obese' and in doing so extend the stigma of being a bit chubby from body image alone to body image plus health. This is despite there being no evidence at all showing that being overweight is unhealthy.

"Our results are similar to those from other recent studies, confirming that underweight and obesity class II+ (BMI > 35) are clear risk factors for mortality, and showing that when compared to the acceptable BMI category, overweight appears to be protective against mortality."

This is a pretty consistent finding - far from being chubby shortening our lives, the reality is that is probably extends them. If we were - given what the evidence tells us - to redefine healthy and unhealthy weights so as to direct appropriate interventions, a better definition would focus 'obesity' on people with a BMI in excess of 35. But were we to do this the numbers might fall from 'two thirds of adults and a third of children' to '5% of adults and 1% of children' - still a lot of people but not exactly a crisis. Such a change would challenge the huge sums being spent on anti-obesity campaigns and would call into question the ongoing campaigns against sugar, fat and the working class diet.

I am repeatedly told by public health folk that their work is 'evidence-based'. And they are very quick to point out studies that support their position. But when the evidence - as we see here with obesity - challenges the preferred position (and funding - Bradford spends over £2 million on its obesity team) it is simply ignored. By not fitting the narrative - 'global obesity crisis' - the pesky evidence undermines the strategies of public health and brings into question its programmes of work. This cannot be allowed.


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