A popular narrative: In the past, we thought obese people were that way because they lacked willpower and ate too much food, particularly fat, which obviously made you “fat” – it’s called fat! Then, scientists who had previously been silenced by the nutrition science establishment (which was in Big Sugar’s pocket) bravely spoke up and educated us on the Science!, and now we know that it’s sugar, not fat, that makes you obese.
Reality is more complicated.
The supposedly debunked “fat = evil” paradigm was never a scientific consensus, but merely a pop-science one. It was less the work of the nutrition scientists than of sugar companies and the makers of low-fat diet products. The supposedly triumphant “sugar = evil” paradigm also has little support amongst nutrition scientists. At best, they are marginally more concerned with the impact of sugar on health than they were 50 years ago, and marginally less concerned about fat.
It isn’t hard to blow the simplistic anti-sugar position out of the water. This graph does it impressively, and should make everyone update their beliefs significantly away from thinking that sugar is a major cause of obesity, and should absolutely torpedo the simplistic “sugar = evil” position that has taken hold in many parts of the population and, seemingly, in government.
A paradigm shift has indeed occurred, but in the popular conception of nutrition science, rather than in nutrition science itself. The pop-science position has gone from simplistically demonising fat to simplistically demonising sugar, with only passing reference to science in the process. This disconnect between scientific and pop-science consensuses is common; explore Scott Alexander’s essay Learning to Love Scientific Consensus for more detail.
Nutrition science is complicated, and individual studies of limited worth. Dishonest charlatans can pull out a few studies, obfuscate their meaning a little, and make it look like the scientific consensus is whatever they want. Only by taking a view of the entire field can one have any hope of making sense of it. The water is further muddied by the state of reporting on nutrition science, which is so bad that media reports of the science often bear no resemblance to the science itself.
If you don’t want to take my word on what the current consensus nutrition science research is, then well done! I recommend starting with Stephan Guyenet’s The Hungry Brain, which provides a solid overview of the current consensus science. If you don’t fancy a whole book, I recommend Alexander’s review of it.
Providing incentive structures can be an effective way to change people’s behaviour, but providing overly simplistic, misguided incentive structures for a system as complicated as this has a long history of producing woeful unintended consequences. Furthermore, awarding the implicit approval of the government to a scientifically unsound oversimplification of a complex field into “sugar = evil” actively harms people’s understanding of nutrition science, making it harder for them to make informed choices.
The sugar levy isn’t just an illiberal, meddling measure to make sure the poor make government-approved trade-offs between the few pleasures available to them – it’s also a scientific nonsense, so we shouldn’t back it.
* Ben Wōden has been a member of the Liberal Democrats since 2010 and lives in Reading.