According to yesterday’s SMH,
Australia has overtaken the US to become the fattest nation in the world, with more than 9 million adults rated as obese or overweight.
But is this true? According to the most recent Australian National Health Survey, 35.4% of Australians over the age of 18 are overweight, and another 17.9% are obese, making 53.3% of us fat. That’s about 7.4 million people.
According to the American National Health and Nutrition Examination Survey, 66% of Americans are overweight or obese, with 31.4% obese.
Both surveys class people with a Body Mass Index of over 30 as obese, and those with a BMI of 25 or more but less than 30 as overweight.
So while we are a nation of fatties, on these statistics we are still a fair way from being the world’s fattest, our 53% lagging well behind the American 66%.
So where did the SMH claim come from?
Though the document itself does not make the claim, someone associated with the Baker Institute’s Australia’s Future ‘Fat Bomb’ publication must have briefed journalists on this factoid, because it was widely reported in the ‘Fat Bomb’ coverage, eg here and here.
There are two problems with the fattest nation claim. First, it claims the American obesity rate is 25%, when it is in fact higher than that. And it puts Australian obesity at 26%, when previous research just a few years ago had it at 18%. Such a large jump in a few years should cause scepticism, and indeed it seems that the 26% figure comes from the results of the National Blood Pressure Screeing Day in 2007, which relied on passers-by various testing stations having their blood pressure taken, along with height and weight statistics. Pretty clearly overweight people are more likely to worry that their blood pressure is too high, and so to volunteer to participate in this screening. The sample was biased towards overweight and obese people.
Of course there is still a scale-busting problem here. But the fattest nation factoid is fiction, which has become truth by careless repetition.