Except in the study they found that people who were in higher socioeconomic status now still had the issue. This wouldn't apply most likely, as they most likely more healthy and well nourished now
Not necessarily, wealth alone may not be enough to change established habits. The overeating could be related to "bluff food" that tastes like it would supply much of a given nutrient which it actually lacks. In that case, the direct cause would be the body trying to compensate a low level of that nutrient by eating more of the food that tastes like it would contain it. And while wealth might help to not even start with that bluff food trap, getting wealthy after establishing a habit for it will just allow to buy more.
I've been idly thinking about bluff food as well, thanks for putting a name on it. Is there evidence for the concept, do we crave bluff food that corresponds to our deficiencies?
What are the most common kinds of bluff food and do you think anything could be done about it?
Sorry, no citable sources, just reading between the lines of "processed food is bad" and the dissatisfying explanations usually given in that context.
What we do know is that animals and humans have a natural ability to balance their diet (by developing seemingly random cravings?) and that this ability is increasingly breaking down in "western civilisation". It is a small jump from that to the idea that market driven "yummy engineering" could be the perfect setup to find the fault lines in our diet balancing instincts.