Poor fat people

Contrary to Oliver Kamm's thesis that blogs limit the range of political debate, I find it has opened it up so that now my regular reading includes some stimulating and well-argued positions I instinctively disagree with and would not otherwise be so exposed to.

At the head of the list, is Chris Dillow's blog Stumbling and Mumbling. In a recent post, he asks "Why are the poor so fat?", concluding:

Economic insecurity, [a recent paper] says, causes weight gain for men. In the US in 2000, each one percentage point higher probability of becoming unemployed is associated with a one pound gain in weight; figures refer to the year 2000.
This suggests a basic evolutionary (subconscious) mechanism is still at work - animals store up fat as a larder against future bad times.

That's plausible at first sight, but I think two other points can be made here.

Firstly, they are rich enough to get fat; even the poor can afford to overeat, sometimes to the point of obesity. While this supports an idea I generally denegrate - that "relative poverty" is a valid idea and can affect people's psychology - it also raises a question about how meaningful the word "poor" is in this context.

Secondly, this disregards what I think of as the KwikSave Effect: poor people buy highly processed, unusually fattening food. The better-off buy raw ingredients and eat more heathily, though not necessarily at greater actual cost (it's very hard to pay more, even at The Dorchester, for potatoes, oil, water, sugar and flavourings than you do when you buy a fizzy drink and a bag of crisps from a budget supermarket).

This raises the possibility that the paper Dillow cites has found a correlation rather than a causality. A different argument, based on the same information, could run as follows:

The most processed ("value-added") food is the most heavily advertised and the most fattening. People with the greatest susceptibility to advertising will therefore tend to be the fattest.

There is a causality between intelligence and wealth: clever people are worth more and get paid more, on the whole, than less clever ones.

There is a causality between intelligence and the ability to see through, place in context and ignore advertising messages.

So relative poverty does not lead to fatness. Rather, low intelligence leads both to relative poverty and to the consumption of heavily advertised foods that in turn lead to fatness.

A measure of the success of capitalist and free-market economies is that in these, and in no other forms of society, even the relatively worst-off can afford to get fat. A measure of the sort of problem capitalism can generate (in this case, predatory advertising) is that the poor do get fat.