How public health promotes bad science

There's a pretty good article in Nature about the 'obesity paradox'. This is the consistent finding that, especially as people get older, being overweight seems not to be quite the health problem that we thought it was. The problem is that this sort of finding confounds the efforts of the public health business to push out a message around obesity - so they want those presenting this science to be silenced:

Some public-health experts fear, however, that people could take that message as a general endorsement of weight gain. Willett says that he is also concerned that obesity-paradox studies could undermine people's trust in science. “You hear it so often, people say: 'I read something one month and then a couple of months later I hear the opposite. Scientists just can't get it right',” he says. “We see that time and time again being exploited, by the soda industry, in the case of obesity, or by the oil industry, in the case of global warming.”

The person making this statement is a leading public health academic at Harvard not some sort of local council junior. The campaign message - being fat is unhealthy - cannot be undermined by inconvenient evidence that says this:

A team led by Katherine Flegal, an epidemiologist at the National Center for Health Statistics in Hyattsville, Maryland, reported that people deemed 'overweight' by international standards were 6% less likely to die than were those of 'normal' weight over the same time period.

This approach undermines science and results in bad policy-making. If it's the case that being overweight but not obese doesn't represent a health problem in most older people (in fact quite possibly the opposite) then we should say so not try to suppress the evidence because the public might be confused.

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