Tuesday 19 August 2014

The Fat Lie (plus Channel 4 News)

Yesterday, the IEA published my latest report—The Fat Liewhich presents some of the evidence mentioned previously on this blog related to calorie consumption and obesity. The following is a summary of some of the main points, but please read the whole report which can be downloaded free of charge here.

Obesity prevalence has increased sharply in Britain since the 1970s. Many public health campaigners portray Britain’s obesity ‘epidemic’ as being caused by the increased availability of high calorie foods, sugary drinks and larger servings in restaurants. This view has been reflected in television programmes such as The Men Who Made Us Fat (BBC), which focus on the supposed rise in calorie consumption while paying little attention to the other side of the equation: physical activity. Some campaigners explicitly dismiss physical activity as a factor. For example, Aseem Malhotra, science director of Action on Sugar, says that ‘it’s time to bust the myth of physical activity and obesity’.

Today, the IEA has released a briefing paper that demonstrates that this conventional wisdom has no basis in fact. If people are ‘being bombarded every day by the food industry to consume more and more food’, as some claim, then the industry has failed. Consumption of calories - and of sugar and fat - has fallen significantly while obesity rates have risen.

The Department for Environment, Food and Rural Affairs (DEFRA) has carried out annual surveys of the British diet since 1974. These surveys are based on diet diaries compiled by a cross-section of the public and are supported by till receipts (DEFRA, 2013). Shown in the graph below, these data indicate a significant decline in daily per capita calorie consumption in the last forty years, from 2,534 in 1974 to 1,990 in 2012. This represents a decline in energy consumption of 21.5 per cent.

This is corroborated by the National Diet and Nutrition Survey (NDNS) which began in the 1990s, the results of which can be compared to the Dietary and Nutritional Survey of British Adults which holds data for 1986/87. These surveys collect data for food and drink consumed inside and outside the home. Shown below, they indicate that average calorie consumption has fallen by 9.8 per cent for 19-64 year olds since 1986/87.

Both datasets also show a decline in per capita consumption of carbohydrates (including sugar) and fat (including saturated fat).

It is clear that average body weight has been rising for decades while average calorie consumption has been declining. Assuming that the laws of thermodynamics are correct, there can be only one explanation for this: Britons are, on average, burning fewer calories than we used to.

This should not be surprising. The transition from manual labour to office work saw jobs in agriculture decline from eleven to two per cent of employment in the twentieth century while manufacturing jobs declined from 28 to 14 per cent of employment. Britons are walking less (from 255 miles per year in 1976 to 179 miles in 2010) and cycling less (from 51 miles per year in 1976 to 42 miles in 2010). Only 18 per cent of adults report doing any moderate or vigorous physical activity at work while 63 per cent never climb stairs at work and 40 per cent spend no time walking at work.

Outside of work, 63 per cent report spending less than ten minutes a day walking and 53 per cent do no sports or exercise whatsoever. Add to this the ubiquity of labour-saving devices and it is clear that Britons today have less need, and fewer opportunities, for physical activity both in the workplace and at home.

Obesity features so often in the media that it is surprising that the data shown in this briefing paper are not better known. The myth that Britons are consuming more and more food has persisted for the following two reasons:

Firstly, there is a tendency to import narratives from the USA where, in contrast to the UK, calorie consumption rose in line with obesity rates for many years. This dual trend had come to an end by 1990, however, and the role of chronic physical inactivity is beginning to be acknowledged as the driver of rising obesity in the years since.

Secondly, the food supply is a more inviting target for health campaigners than the sedentary lifestyles of the general public. A war against ‘Big Food’ requires no stigmatisation of individuals (other than the individuals who work in the food industry) and there are a readymade set of policies available which have been tried and tested in the campaigns against tobacco and alcohol. Instigating such a war, however, requires the public to believe that food companies have acted unscrupulously by stuffing unwitting consumers full of calories, forcing large portions upon them and spiking their meals with sugar and fat. The data shown in this paper are clearly not helpful to that narrative.

Such is the sensitivity of the public health lobby to this sort of information that when two researchers published a paper showing that sugar consumption had been declining in Australia for thirty years while obesity had been rising, they were branded ‘a menace to public health’ and investigated for scientific misconduct. They have since been exonerated, but the title of their study - ‘The Australian Paradox’ - highlights how deeply rooted is the belief that obesity can only be the result of increased sugar and/or calorie consumption at the population level. As the evidence from the UK - and, in recent times, the USA - shows, it is no paradox at all.

Reposted from the Institute of Economic Affairs.

See also Tim Worstall and James Dellingpole on this topic.


I went on Channel 4 News to talk about this report (you can watch the interview here).  I confess to getting rather irritated half way through, which I regret because it doesn't go down well with viewers, but I had due cause. I had expected that whoever I was up against would say something along the lines of "OK, people are eating fewer calories but they're still eating too many calories considering their sedentary lifestyle". Then we could argue about policy. I wasn't expecting somebody to flat out deny that calorie consumption has fallen at all, let alone insist—without a shred of evidence—that it has actually risen.

That, however, is what Prof. Mike Lean of Glasgow University decided to do. He pointed out that nutritional evidence is self-reported and is therefore prone to misreporting. He also pointed out that obese people tend to misreport more than slim people. If he had read my report he would have known that this was not news to me. From page 17-18 (under the heading 'limitations'):

Measuring the diet of the nation is not an exact science. Researchers rely on individuals keeping track of what they eat over a period of several days and it is well known that people tend to under-report the amount of food they consume due to a desire to deceive or - more commonly - a tendency to forget (over-reporting is also possible, though less common). The alternative method of keeping till receipts to check what food has been purchased is also problematic because some food is thrown away.
Researchers are well aware of these issues and have ways of testing the degree of under-reporting, notably with urine tests using ‘doubly labelled water’ which show how much energy a person has expended (and, therefore, how much energy a person of steady weight has consumed). Nevertheless, it is believed that Britons throw away about 10-20 per cent of the food they buy and under- report how much they eat by around 20 to 40 per cent (WRAP, 2013; Macdiarmid and Blundell, 1998).
When studying dietary trends over time the question is not whether people under-report but the extent to which under-reporting has changed over the years, if at all. Women and the obese are most likely to under-report and whilst the proportion of women in the population has remained stable, the proportion of obese people has clearly increased. It is therefore possible that more obesity has led to more under-reporting, but it is very unlikely that the population has become so forgetful and dishonest that the large, steady and virtually uninterrupted decline in calorie consumption reported in successive studies can be explained by misreporting alone.

So there is no doubt that people misreport. The only question is whether they systematically misreport far, far more today than ten, twenty or thirty years ago. I can find no evidence that they do and the other sources of evidence, such as food purchases, do not suggest otherwise. As I say in the quote above, food purchase data are not perfect either, because people throw away some food, but it defies common sense to believe that people throw away less food today than they did during the three day week or the winter of discontent.

Having knocked the evidence, Lean then dismissed it completely. Indeed, he said that the reality is the polar opposite of what the evidence shows. It's a common tactic with some keyboard warriors and some of the weaker industry lobbyists—skim a paper, look for the limitations, and then claim that the mere acknowledgement of limitations renders the whole paper worthless. Having dismissed the evidence, insert your own subjective opinions as if they were fact. Never mind that the vast majority of epidemiological evidence—including virtually all evidence on nutrition and cancer—is based on self-reporting and, therefore, is subject to misreporting.

When asked for evidence of his own, he started to quote a study, albeit a barely relevant study, from the USA, thereby proving a point I made on page 24 of The Fat Lie when discussing the reasons why the myth of heavier eating has persisted:

Firstly, there is a tendency to import narratives from the USA where, in contrast to the UK, calorie consumption rose in line with obesity rates for many years.

But—what d'ya know?—the myth is falling apart in America too, as shown in the recent study published in the American Journal of Medicine which found that:

Our findings do not support the popular notion that the rise in obesity in the U.S. can be attributed primarily to sustained increases over time in the average daily caloric intake of Americans... Average daily caloric intake did not change significantly [between 1988 and 2010]. BMI and waist circumference trends were associated with physical activity level but not caloric intake.

Lean's policy of point blank refusal to accept any of the evidence from DEFRA, the British Heart Foundation, the Department of Health, the Institute of Fiscal Studies and the Office for National Statistics turned the discussion into a question of trust—who do you trust: the professor or the increasingly irate free market think tanker? Obviously, the average viewer has no inclination to dig into the data so is going to side with the professor.

British Heart Foundation, 'Coronary Heart Disease Statistics', 2012

Institute for Fiscal Studies, 'Gluttony in England?', 2013

Krishnan Guru-Murthy helped him out by ending the interview with the tiresome question of whether 'Big Food' funded the IEA report. They didn't, of course. Readers of my books, articles and blog posts over the last five years know which topics spark my interest and I'm lucky enough to be able to write about more or less anything I like within the field of public health policy at the IEA. I don't need any suggestions from commercial interests. As for whether 'Big Food' funds the IEA at all, I honestly don't know and I honestly don't care. I don't really know which companies even make up 'the food industry' but it must be a very broad church (I'm from a long line of farmers so I guess I have 'links' with 'the food industry'). The IEA has always had a policy of donor confidentiality so I wouldn't say who funds it even I knew, which I usually don't. But I'm quite happy to say, as I did in this interview, that people are welcome to assume that we are funded by x if that means that we can move on to talking about the issue at hand.

An appeal to authority and a little innuendo about funding goes a long way with the average couch potato—probably more so on Channel 4 News than on most programmes—so I don't doubt that Mike Lean won the debate in many people's eyes. Hey, ho. Hopefully some people read the report regardless.


Unknown said...

Mike Lean has ties to the food industry!! CSO for eat balanced ...


I guess that makes his views invalid ;)

There's even a picture of arch capitalist and multimillionaire Deborah Meaden on the same page ...

I just can't believe these people are using markets to promote their "healthy" food ... how dare they!! ;)

BrianB said...

Don't beat yourself up Chris, you didn't come across as exceptionally irritated, just annoyed with a smug - albeit softly spoken - git who quite happily tried to dismiss your work as "hooey". I think most people would feel your response was pretty proportionate in the circumstances. I would probably have just called him a lying c*nt, but that's because I have no patience with lying c*nts!

Also, don't forget that the "average couch potato" will take more notice of a news report where there is a bit of a punch-up - as opposed to the polite but dry outpourings of self-satisfied idiots like Lean.

As for whether or not this went down well with viewers - there are 4 comments on the Channel 4 website. Two of these are criticising you - but 50% of these critical comments are from one Simon Chapman! That says a lot.

The other two comments make the salient point about how it suits so-called 'public health' when people 'misreport' their exposure to tobacco smoke, which leads to entirely false conclusions about passive smoking 'risks'. Such PH hypocricy need calling out at every opportunity.

Finally a word of advice. When you are asked the (inevitable from biased interviewers) question about funding, you should reply along the lines of "I will answer that question when Mike Lean identifies his own funding links with pharmaceutical and other beneficiary industries". He will, no doubt, deny it - but if he is lying, he won't do so too many times.

All in all, I enjoyed your spirited performance. I absolutely despised Lean from the moment he said "we who know about obesity and public health...". Ugh! What incredible, and quite unnecessary hubris!

Jonathan Bagley said...

As one who sees great merit in the high fat/low carbohydrate theory, I first thought that the increase in obesity could be explained by a decrease in the proportion of calories from fat between 1974 and 2012. However, from your figures, and the fact that 1g of fat equates to 8.8 cals, it can be seen that the proportion of calories from fat has decreased from 39% to 36%; on the face of it, not much of a fall. Supposing protein calories stayed constant as a proportion of total calories, this 3% decrease would have been compensated by an increase in the proportion of carbohydrate calories. The fall in total calories is so large that this is possible together with the recorded decrease in absolute carbohydrate consumption. However, if this did occur, I've no idea if it would have been sufficient to precipitate the growth in obesity.

If we discount this explanation, the only others seem to be that some of the food statistics are wrong, or that your lack of exercise explanation is correct. The figures from independent sources broadly agree, yet I find the exercise explanation difficult to accept. Calorie intake fell from 2534 to 1990 between 1974 and 2012. This represents an enormous amount of physical activity. The examples you give for the decline in walking and cycling are almost insignificant in calorific terms. A mile walking roughly equates to 80 calories and you quote a yearly (far less than a mile a day) decrease of 76 miles between 1976 and 2010. I don't think the decline in manual labour is sufficient either. 540 calories a day is an hour, for a fit person, of really hard physical exercise in a gym or over seven miles of walking. Was there a large enough decline in this kind of work. I'm open to persuasion. Perhaps the decline in manual work and all the small things really do add up to population average of 540 calories. I'm sceptical?

Phönix said...

Its a simole equation for Kcal: Food in - living/exercise out. Every 7000 Kcal on one side of the balance means 1 Kg body weight more or less.
Its not rocket science.
I know people prefer fairy tales.

Junican said...

I too thought that your annoyance was fully reasonable. The (quack) prof had just implied that you are a 'silly boy', messing in things that you know little about.
I sometimes wonder if presenters are briefed to let the profs speak uninterrupted, but to jump in and mess up your chance to speak. It seem to happen an awful lot.
On the topic, it seems perfectly obvious to me that the fall in physically taxing jobs must have an effect on the need for calories consumption generally. The balance of physical activity and calories consumption is what matters. The important thing to me is that it is a matter for the individual to work out for himself. Personally, I don't think that it matters much what you eat. Constantly eating too much of anything will cause weight increase, depending upon each individual's metabolism. Personally, I think of exercise as a means of toning the muscles, and certainly not a means of weight loss. And you don't need to do an awful lot of exercise to keep your muscles in decent shape.
What I object to, and I am sure that this is one of the reasons for your report, is the constant attacks from the fascists in health zealotry upon major industries and the their propaganda tactics.

Jean Granville said...

Nice paper, but I still don't understand how they measure the weight and the weight/height ratio of the population.
In England, there are a lot of different groups with different heights. South-east-Asians are usually smaller than Norther Europeans, for instance. Then, people eat and behave differently according to a lot of different parameters. How can you possibly find a representative sample? And if you find one for England, how can you possibly use it for an international comparison? Even for a comparison between now and the 50's or the 80'?
The rest of the data must be roughly reliable, but I have some doubts about the population weight data.

Dan said...

There's another factor they haven't considered: heating. People are mammals. Mammals spend a huge amount of their energy intake on maintaining a stable body temperature, which increases in cold conditions and decreases in warm conditions.

I was born in 1970 and remember what houses were like back then. In winter, brisk, cold and similar adjectives were the ones to use; growing up I had effectively no heating in my bedroom at all, and only two gas fires downstairs which were rarely if ever run anywhere near full output.

We lived by putting on more insulating clothes and by putting up with the temperatures, and much more of our food was metabolised to keep us warm.

Nowadays central heating is the norm. My house is set to maintain fifteen degrees inside come what may, and to boost this to twenty one if it can in the mornings and evenings. Life is much, much more comfortable, and spending more time in such palatial luxury can only make us fatter.