Earlier quoted context omitted.
> fails to explain why people eat more calories now than they did before Wouldn't this also intuitively be related to the fact that a calorie today is much, much "cheaper" (in terms of labor required to acquire the calorie for both the producer and the consumer) than a calorie was even 100 years ago due to advancements in agriculture and distribution?
To an extent, but we're 10x richer than we were in 1900; we do not eat 10x as many calories. And it's poor people who eat more calories now, not rich people.
That's my point; if you look at a map of obesity rates in the US overlaid with a map of poverty, there's a very strong correlation.
The cheap access to calories today makes it easier to overconsume. In the past, the high cost of calories meant that only the wealthy could really ever become obese (outside of genetic factors).