Theodore Dalrymple, whom we've met in these pages before, has written a very useful article in the Telegraph analyzing the root causes of the obesity epidemic among the poor. His analysis is oriented towards Britain, but it applies pretty well (in my experience, at least) to inner-city America too. Here's an excerpt.
... what we eat also has a social dimension. You can lead a man to a doughnut, but you can’t make him eat. What is the connection between poverty (relative, not absolute), and the obesity that is unprecedented in history?
. . .
It is ... in social changes that the explanation, or at least an important part of it, is to be sought.
With the decline of the family – wrought by the policies of successive governments – patterns of eating have changed. Meals in many households, especially those of the relatively poor, are no longer family or social occasions. It has been found that a fifth of children do not eat more than one meal a week with another member of their household; and in such households, which I used sometimes to visit as a doctor, the microwave oven was the entire batterie de cuisine, or at any rate the only cooking implement that was ever actually employed.
Moreover, there was no table at which a meal could have been eaten in common if anyone had thought of doing so. The result was that children became foragers or hunter-gatherers in their own homes, going to the fridge whenever they felt like it and grazing on prepared foods – high, of course, in the evil fructose. Not coincidentally, these households were also the least likely to have what would once have been considered the normal family structure.
Such households also tended to be in areas called “food deserts”, in which fresh produce is either not easily available or unavailable. But those who ascribe the dietary habits of the households I have just described to food desertification put the cart before the horse: for if heroin can reach these areas (and it can), surely the humble lettuce can do so?
. . .
... food desertification and the supposed cheapness of industrially prepared foods is a consequence, not a cause of, the food habits I have described. Food desertification is a symptom of the culinary ignorance, incompetence and indifference of a substantial minority of our population: ignorance, incompetence and indifference unopposed by any attempt of our educational system to counteract it, for example by teaching girls the elements of cookery. Fat is indeed a feminist issue, but not in the sense that Susie Orbach originally meant it.
Another contributory factor to the obesity epidemic is the control or authority now given to children over what they eat. Children are asked (and given) what they want by their solicitous mothers, not as a treat but as a matter of course; and what they choose is what is most immediately attractive to them.
This has the delightful short-term consequence of forestalling the struggle to get the children to eat what at first they do not want to touch; but it has the disastrous long-term consequence of restricting their repertoire and of keeping their tastes childish and undeveloped, that is to say likely to cause obesity.
. . .
It is not the combination of poverty and the easy availability of fattening food that has produced the epidemic of obesity: rather it is a sense in these circumstances of meaninglessness, that nothing much matters.
There's more at the link. Insightful and authoritative - and deeply troubling. Highly recommended.