Many people believe that obesity is caused by a lack of moral fiber. That is, those who are overweight are in their situation because they lack the willpower necessary to keep in shape. If only they had a stronger backbone, they’d be fit.

But this is simply not the case, says Zoe Williams in the Guardian.

There is a widespread underestimation, or blank refusal to admit, how much cheaper cheap food really is. It became a mantra of the mainstream, as obesity started to define the pathology of this century, that the problem was not poverty, it was education. This was based on two facts. The first was that everybody, except affluent women, was getting fatter. So it couldn’t be related to poverty, since it was hitting upper-middle class men.

The second was that an organic vegetable box would always be cheaper than a pack of Findus Crispy pancakes; therefore the more healthily you ate, the less you would spend. And I saw plenty of counter-arguments to that, identifying poor eating habits as a result of deprivation. One was that people with kids and very little money can’t afford to waste food, so have to buy things that children are likely to eat, which more or less means food with too much salt and not enough fresh vegetation. Another was that people battling food scarcity tend to overeat when food is available, and depending on what they’re overeating, a missed meal the next day won’t compensate for that.

Both of those propositions make sense, but I rarely heard people say, just look at the phenomenal value for money, calories-per-penny in a McDonald’s. It blows your mind how cheap a £1 cheeseburger is; crisps are even cheaper. Cheap foods are fatty, and the whole point of fat is satiety. If you look at fresh vegetables in the old-fashioned way, as fuel, rather than the modern way, as an embodiment of morality and self-governance, they are terrible value, especially the organic ones.

So, why do people make sloth argument? And what are the implications of thinking about obesity differently?

I think there’s an element of projection here, where people who can afford to eat well – and do – still secretly yearn for a Big Mac, and it’s their own yearning rather than political deliberation that makes them think they’re looking at a lack of willpower from the McDonald’s classes. But this has nothing to do with willpower.

I understand this strenuous avoidance of reality. Once you accept that crap food is an economic, not a moral choice, you have to accept a whole raft of unpleasant outcomes as a function of deprivation, not an illustration of a lack of backbone. You have to accept that 24,000 “lifestyle-related” yearly deaths from diabetes are related not to sloth but to poverty. Sure, it’s still a lifestyle, but it’s not a choice. You have to accept that the education agenda against obesity – vegetables and regular exercise – will never work (that should be obvious, just by looking at the data or, failing that, just by looking around).