Childhood Obesity “Levelling off”

This was on lots of news channels – I caught Tam Fry (National Obesity Forum) talking about it on BBC Breakfast and then someone (didn’t catch his name) on Radio 4’s Today Programme. There were press articles all over the place – most very misleading.

The “Independent” headline was “Childhood Obesity ‘has peaked’ “, and it then opened with the following:

The 30-year rise in child obesity may have peaked (Zoe note – so we’ve already gone from ‘has peaked’ in the headline to ‘may have peaked’), researchers report. The increase in overweight and obesity among children which has continued without pause since the mid-1970s is now on a downward trajectory, according to latest figures.

Let’s try to decipher this little gem – the increase is now on a downward trajectory. That means the increase is going down. That means the numbers are still going up, but just at a slower rate!

Every increase, that is not exponential, does go down! (For those interested in maths – only the rare occasions where the second derivative is positive can increases continue). Obesity has increased 8-10 fold since the 1970’s (in men and women respectively). If it increased 10 fold again in the next 30 years, 250% of us would be obese! That’s why the increase has to go down at some point.

AND – all of this is talking about forecasts – in fact the entire news story is about forecasts. The story is – we thought that 14% of girls would be obese by 2020, we now think 10% will be! But these are still forecasts and we could have been wrong the first time, or we could be wrong now. We’re still getting fatter!

I particularly liked this next bit of the Independent article: “The pounds are also slipping off teenagers. Among 12 to 19 year olds, the forecast number of obese girls in 2020 is down from 30 per cent to 9 per cent and obese boys are down from 25 per cent to 18 per cent. There are similar falls in overweight teenagers”.

No pounds are slipping off anyone. There are no falls in the number of overweight teenagers – we are still talking about forecasts.

Even better was the Public Health Minister, Gillian Merron, claiming credit (funny how public health bodies didn’t rush to take the blame): “The encouraging news that child obesity may be levelling off is thanks to the hard work of families, schools and the NHS across England, supported by Government initiatives such as 5 A Day and Healthy Schools, which have overseen improvements to school food and school sport.”

Dear Gillian – please see explanation above….

This is bad science at its worst.

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