Sunday, October 14, 2007

Fatty Stats

Alan Johnson, the Health Secretary, last night compared the challenge posed by obesity to that of climate change and promised radical new measures by the government to try to reverse the tide.

'We know we must act. We cannot afford not to act', he said. 'For the first time we are clear about the magnitude of the problem: we are facing a potential crisis on the scale of climate change and it is in everybody's interest to turn things round.'
That was from today's Guardian Unlimited; and similarly, from today's BBC News, the following:
Dr Colin Waine - who chairs the National Obesity Forum - said that in terms of its impact on society, the health threat posed by obesity "will hit us much earlier than climate change".

He added: "We are now in a situation where levels of childhood obesity will lead to the first cut in life expectancy for 200 years. These children are likely to die before their parents."
That comparison, of obesity increase with climate change, seems bizarre given the global nature of the latter, which affects the poorest most greatly (not to mention how much of the former problem could in principle be addressed by the individuals concerned; and so forth)... Anyway, for a sign (possibly) that these people don't know what they're talking about, consider the last sentence quoted (which was conveniently both striking and vague):
......Suppose that the projected fall in (average national) life expenctancy does mean that these children will tend (on average) not to live as long as their parents (which is a bit vague); still, parents are presumably not much younger than about 20, on average, when they have their first children, so for current children to be likely to die before their parents we would need to be looking at that sort of drop in average life expectancy (over the period of one generation). But much of the population will not be going from normal to obese; and even in the part that does go that way, adults will too (e.g. adult rates of obesity have risen by 50% in the last decade), whereas the likelihood in question depends only upon the difference between child and adult rates...
So, since it seems unlikely that a sudden drop of decades, in average life expectancy, is to be expected, I suspect that Colin wrongly pictures his projected fall as children dying before their parents (maybe because such is widely regarded as unnatural, and therefore striking, depite childhood mortality not being naturally this low:)

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