Sure, that could be possible. However there are some issues:
1) Obesity isn't a disease of the rich. So the "cheapness" doesn't seem to be an obvious factor. This is in contrast to the 1600s and 1700s when obesity and gout were diseases of the rich in Europe.
2) In poor areas, especially the third world, we are starting to see a pattern obese mothers and malnourished children. This is bizarre. The usual pattern is to see malnourished mothers and malnourished children.
3) We can simulate the syndrome with insulin injections, which seems to suggest at least one hormonal pathway driving overeating (rather than simple psychology).
4) Women get fat after menopause (hence the estrogen supplementation industry, which turned out to be giving them cancer). Everybody starts to put on pounds at middle age. Kids seem to start eating a lot at puberty, but generally grow up rather than around. It seems like the whole system is much more complicated than "cheap, tasty food."
I know what you're saying, but consider the counterfactual (ie, almost all history to this point).
In the absence of cheap, tasty food, obesity is rare.
When cheap, tasty food is abundant, so too are overweight and obesity.
On a population level it looks very much like cheap, tasty food is both necessary and sufficient. Without an increase in per-capita calories, there can't be an increase in population BMI.
The reason we call all these other phenomena strange is because we've never had tens of millions of overweight and obese subjects before. Sample sizes of tens of millions throw up new and interesting outliers. It's only going to get weirder.
1) Obesity isn't a disease of the rich. So the "cheapness" doesn't seem to be an obvious factor. This is in contrast to the 1600s and 1700s when obesity and gout were diseases of the rich in Europe.
2) In poor areas, especially the third world, we are starting to see a pattern obese mothers and malnourished children. This is bizarre. The usual pattern is to see malnourished mothers and malnourished children.
3) We can simulate the syndrome with insulin injections, which seems to suggest at least one hormonal pathway driving overeating (rather than simple psychology).
4) Women get fat after menopause (hence the estrogen supplementation industry, which turned out to be giving them cancer). Everybody starts to put on pounds at middle age. Kids seem to start eating a lot at puberty, but generally grow up rather than around. It seems like the whole system is much more complicated than "cheap, tasty food."