Subbing for Ezra Klein, Mike Konczal analyzes food prices and purchasing decisions. He concludes that the poor have it worse than some would believe

The poor have more purchasing power because, in part, they are buying food that isn’t very healthful. And the important thing about this different inflation rate quantification for income inequality is that nobody
gets diabetes.
The long-term health costs of "choosing" a different inflation rate for your food isn’t estimated, nor are they included to see if it all balances out economically.

There are important points here that I am sensitive too. However, I simply must drive home the point that the underlying logic is built on a mountain of speculation. We don’t have a really solid explanation for why people are poor. We don’t really have a really solid sense for what food is healthy nor how food contributes to long term disease. We have mountains of speculation. However, recognizing them as such is important because we have seen such mountains before.

Here are a few links to some promising treatment to a form mental illness recognized during the 20th Century

The application of anticipatory avoidance to the treatment of homosexuality

A learning approach to the treatment of homosexuality

Treatment of Homosexuality by Individual and Group Psychotherapy

The authors of these well published scientific studies developed methods which they sincerely believed to be effective in treating a psychological disorder.

We now know that not only is homosexuality not a disorder but it is almost certainly not “psychological” in the sense meant by these authors. That is, at this point it seems all but certain that people are either born gay or straight and that no series of life events can affect this.

The drama here is easily lost, so let me repeat. These were scientific papers reporting the successful psychological treatment of what we now know to be congenital traits. To be even more blunt -  they were reporting empirical success in accomplishing something that is not even logically possible.

Moreover, at the time they were well within the conventional wisdom and strongly supported by a theoretical framework. This was not quackery – yet it was deeply, deeply wrong.

To wit – it is very, very easy to get carried away with a theory of disease, disability or affliction. Passions run high. Prejudices run deep. Really useful data is frustratingly hard to come by. And fueling it all is the conviction on all sides that “something” must be done. Even if that something is to justify away the problem.

So I am strongly urging everyone involved to be careful assembling our very shaky models of health on top of shakier models of nutrition and then combining those with our almost complete ignorance of the deep causes and consequences of poverty. Such an assemblage quickly becomes an edifice of supposition and the foundation of potentially hurtful policy.

I am have my own prejudices on these issues and in full disclose they run slightly counter to Mike’s. However, this isn’t about who is right. This is about the need for everyone to tread lightly.