Tuesday, 10 December 2019

Obesity in England: just the facts

The Health Survey for England was published last week, with the latest obesity statistics (for 2018). It didn't receive much media coverage, presumably because there wasn't anything particularly newsworthy in it, but here's a summary for those who are interested.

The rate of adult obesity was down slightly in 2018 - to 27.7% - after a jump in 2017 that always looked like a statistical blip (from 26.2% to 28.7%). Bear in mind that these are only estimates based on a sample and so there is a margin of error. Rates fluctuate from year to year, but on average there has been a rise of two or three percentage points in the last ten years.

The rate is higher among women (29.2%) than men (26.1%). This has been the case ever since the ONS starting tracking obesity in 1993, which makes it all the more peculiar that the consistently useless 'public health' predictions assume that the rate will be higher among men.

Speaking of predictions, it is that time of the year when we see how the Lancet's famous prediction of 2011 is working out. The journal reckoned that the male rate would be between 41% and 48% by 2030, prompting headlines like 'Half of UK men could be obese by 2030'. This looks as unlikely as ever.

By contrast, the number of men who are overweight has always been higher than the number of women who are overweight. The figure for 2018 is 67% and this hasn't really budged for 20 years, so it's safe to assume that the prediction of 80% of men being overweight by 2020 is not going to come to fruition.

Here's the rate of overweight (including obesity) for both sexes combined. It's not very exciting.

Regular readers will know that nobody bothers to measure childhood obesity properly in Britain, but the rate of what is wrongly called 'childhood obesity' was 15% in 2018. This is about the same as it was in the late 1990s and is less than it was in the mid-2000s.

You'll notice that the rate has fluctuated a lot in recent years. This is probably because the sample size was sharply reduced in 2011. Lazy, but why bother making a proper attempt to estimate something that is meaningless?

The most interesting statistics are those which rarely get mentioned. The rate of morbid obesity (ie. a BMI over 40) has been rising more quickly, albeit from a low base. At the start of the millennium, it was around 1.5%. By 2010, it was around 2.5%, and in 2017 it exceeded 3% for the first time.

In relative terms, the obesity rate has come close to doubling since 1993, but the morbid obesity rate has more than trebled. Women are twice as likely to be morbidly obese than men, with one in twenty of them being morbidly obese in middle age. 

So, in this millennium, we have seen a gradual rise in adult obesity, a sharper rise in morbid obesity, no rise in the number of people who are overweight, and a decline in the rate of what they call child obesity.

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