The Horizon programme, screened a couple of nights ago, promised to reveal the ‘surprising truth’ about what causes obesity, and ‘how to fight the fat epidemic’. Recently I read a book by an epidemiology professor called Ian Roberts, “The Energy Glut”, which tackles similar questions, so I was interested to see whether the answers would match.
The short answer is: they don’t.
The Horizon programme was engagingly presented by a slim, pretty and precisely spoken surgeon, Gabriel Weston— presumably not deliberately selected to irk the obese interviewees.
There were a few words in the beginning about how the wide availability of high calorie foods in the developed world might increase obesity levels, and then the narrative sprinted away from the population level, never to return. From then on it was all about individual factors: hormone responses, genetics, foetal programming and surgical interventions.
Not to say that all this wasn’t very interesting. One of the take home messages is that it’s not an individual’s “lack of moral fibre” which is to blame for their obesity, but rather factors beyond their control: the differing responses of their ‘appetite’ and ‘fullness’ hormones compared to non obese people, which in turn is determined not just by the genes they inherit, but whether these genes have been activated early in the life course (in particular, by stress in-utero). Finally, there’s a section on the effect of gastric banding surgery, which acts not only by reducing the size of the stomach, but by somehow prompting a proper ‘fullness’ hormone response. The film ends on a positive note, suggesting there may be a non-surgical ways to achieve the same effect.
It was a well made documentary that presented an interesting, coherent narrative. It nicely wove together new with more familiar science. The stuff on epigenetics, while hardly cutting edge, was particularly fascinating, although it was a shame the ‘Barker hypothesis’ wasn’t mentioned by name, seeing as they talked about foetal programming and even went to Southampton. I can see the reasoning behind this reluctance to use technical words/names, but in reasonably highbrow docs like this it makes more sense— and is less insulting to the intelligence of the viewer— to clearly explain the meaning of important new terms when the concept is first introduced, then use the grownup version through the rest of the programme, rather than constant talk of ‘fullness hormones’ etc.
Good though the film was, if the aim was really to look into the causes of and possible cures for the obesity epidemic, than I suspect— having recently read Ian Roberts and Phil Edwards’ ‘The Energy Glut’— that it spectacularly misses the point.
‘The Energy Glut’ agrees that individuals themselves are not to blame for obesity, but rather than looking at individual factors, it takes a look at the wider physical, transport and social environment. In essence, it proposes that it is the ‘obesogenic’ environment of the modern developed world that causes obesity in our populations- in particular the ready availability and low cost of energy dense food, and the lack of opportunity to burn off calories. Sure, genetic and other individual factors determine why particular people are fatter than others, but because we are part of a population where everyone is exposed to the same energy-dense food/low mobility environment, these factors are not truly causal at the population level (see the work of one of Ian Roberts’ predecessors at LSHTM). In most developed countries, the entire population distribution curve for obesity has shifted fat-wards as we have started eating more and exercising less. This is why the obesity epidemic is an epidemic, and it is a much more convincing explanation for current obesity levels than those provided in the Horizon programme (which actually answer a very different question: why are some people fatter than others?)
The great contribution of ‘The Energy Glut’ to the obesity debate is the coining of the term petro-nutritional complex, which encapsulates the complex, mutually reinforcing linkages between the food, transport, car manufacturing and oil industries in the developed world, much in the same way the term ‘military-industrial complex’ describes similar links between politicians, arms manufacturers and the military in the US (and elsewhere).
Obesity and climate change are closely related problems driven by the same underlying processes: an overabundance of energy-dense food which is made possible by fossil fuel inputs in modern agriculture, food which is provided from car-friendly supermarkets in car-friendly cities, all of which contributes to obesity and climate change in mutually reinforcing positive feedbacks. At times some of the language in the book verges on conspiracy theory-esque, but several clear and well referenced chapters left me convinced of the underlying insight. Perhaps ‘petro-nutritional complex’ isn’t the snappiest phrase for describing this complex web of shared interests, but it’s the best I’ve yet come across— and it deserves wider recognition.
I can’t say I agree with everything in the book. Having spent a little time in the developing world, the idea that Africa doesn’t need roads at all seems a little strange and could come across as deeply patronising (“we’ve reaped the benefits of an industrialised economy and modern transport systems to deliver goods to and from markets, but you can’t have them because they will cook the planet, make you fat and kill too many pedestrians”). He comes down heavily in favour of the ‘contraction and convergence’ formula for reducing CO2 emissions while transferring wealth to the developing world. The problem with supposedly simple formulae that try to do too many things for too many groups, is that often they turn out to be less simple than they initially appear, and don’t end up being attractive to anyone. And so it has proved in the various international climate change negotiations in recent years. Contraction and convergence may be simple on paper (though still requires a full chapter of description in this book), but a carbon tax is simpler still.
Ian Roberts’ main research interest is road accidents (and traumatic injuries generally) and the obscenely high but largely unpublicised worldwide death toll from motorised road transport is clearly a strong motivation for his writing this book. While I accept that there is way too much kinetic energy flying around our streets, I wonder if his background places him a little too close to the negative side of the equation. Unfortunately, the way the world is configured right now, cars and lorries are just way too useful. His solution, the bicycle, is great but will never transport large amounts of goods over long distances, nor bring globalised friends and families physically together across the continents.
In theory of course, a healthy, non-bariatric world of walking, cycling, street parties and efficient train travel is possible. But when I tried to explain the Energy Glut’s solutions to a colleague recently, the response was “good luck with that”. Perhaps it’s what we have to aim for, but I’m not sure the tone and language of this book are going to help get us there.
In short: if both the Horizon programme and the Energy Glut are a little short on the solutions, at least the Energy Glut puts its finger properly on the problem. Horizon essentially mischaracterises the issue and goes on to hint at some potential ‘techno-fixes’ for the obesity epidemic. As in the related problem of climate change, some of these obesity techno-fixes may be useful— even essential to prevent the problem spiralling completely out of control— but sorting out the overarching problem in the long term is going to take something much more fundamental.