From the BBC:
'Weight is healthy' study criticised
A study which suggests being overweight can lead to a longer life has caused controversy among obesity experts.One labelled the findings a "pile of rubbish" while another said it was a "horrific message" to put out.
Boom!
The study in the cross-hairs is a meta-analysis published in the Journal of the American Medical Association which assessed 97 individual studies encompassing a total sample group of 2.88 million people. Not the kind of paper the Beeb would normally be sniffy about, but the meta-analysis found that the overweight and mildly obese people had a lower mortality rate than those of 'normal' weight.
The results for overweight people (BMI of 25-30) were statistically significant (RR = 0.94 (0.91-0.96)) while the results for mildly obese people (BMI of 30-35) were not (RR = 0.95 (0.88-1.01)). I am hesitant to take either of these results as conclusive proof that carrying a bit of timber extends your life, but it seems to me sufficient evidence that it does not shorten it.
Although the findings have been described as "counterintuitive", they really aren't. BMI is an extremely simplistic, nineteenth century measurement and the claim that those with a BMI of 25+ are "overweight" is entirely arbitrary. Moreover, as The Science Bit points out, this is hardly the first time such findings have been recorded.
But they drive 'public health' campaigners wild...
Prof John Wass, vice-president of the [Royal College of Physicians], said: "Have you ever seen a 100-year-old human being who is overweight? The answer is you probably haven't."
So much for systematic reviews and sober science! Are these really the words of a medical man or did the BBC ask a bloke in a pub for his 'folk wisdom'? I thought public health people had rejected any discussion of centenarians after it was shown that they don't generally lead healthy lives?
Wass continues:
"Huge pieces of evidence go against this, countless other studies point in the other direction."
Some do, some don't. That's the nature of epidemiology, hence the need for systematic reviews to assess the weight of evidence, and the weight of evidence points towards a null or protective effect from overweight and mild obesity. I repeat—this is not a single study; it is a review of 97 different studies conducted all around the world over several decades. There are not "countless" studies, let alone countless studies which "point in the other direction". There are dozens of studies which have been counted and, taken together, they indicate that mildly overweight people live longer than the lean.
Other experts criticised the research methods.
Alas, the BBC does not feel the need to bore us with the details of these substantive criticisms and so instead we get a variation of the 'sick quitter hypothesis'.
"Some portion of those thin people are actually sick, and sick people tend to die sooner," according to Donald Berry, from the University of Texas
This is true. As with all epidemiology, causation cannot be proven. Some of the thin people will indeed be sick. But, if being overweight is as unhealthy as the nanny statists claim, some—nay, many—of the fat people will also be sick and therefore be likely to die sooner. The fact that, as a group, they actually die later is a hole in the theory that cannot be blithely dismissed with reference to a single, unquantified and unproven confounding factor. Moreover, the authors address this question and note that "most studies" find that pre-existing disease is not an "important source of bias" and that those which control for this factor found that it had "little or no effect".
Lame as they are, the criticisms above are positively high-minded compared to those which follow.
Dr Walter Willett, from the Harvard School of Public Health said: "This is an even greater pile of rubbish" than a study conducted by the same group in 2005.
Willett made his point even more strongly when speaking on NPR yesterday...
"This study is really a pile of rubbish and no one should waste their time reading it."
How heartening it is to see the spirit of intellectual enquiry thriving at the Harvard School of Public Health. Perhaps Dr Willett and his friends will make a bonfire out of copies of the Journal of the American Medical Association and dance around it.
Tam Fry, from the National Obesity Forum in the UK, said: "It's a horrific message to put out at this particular time.
For God's sake man, it's a meta-analysis in a scientific journal released at the start of the year, not the director's cut of The Innocence of Muslims released at the start of Ramadan.
"We shouldn't take it for granted that we can cancel the gym, that we can eat ourselves to death with black forest gateaux."
This hysterical misrepresentation of the study's conclusion is the final line of the BBC's report. In total, the Beeb quoted four people who hated the study's findings but were apparently unable to explain what was wrong with them. The Beeb did not bother to include any quotes from supporters of the study, nor—and this is highly unusual—from its authors.
Perhaps the BBC's health editor has made a new year's resolution to treat epidemiological studies with cynicism and contempt. That would be most refreshing given their past output, but I suspect the scepticism will be extremely short-lived.
