What don't we understand about the obesity epidemic? The story seems pretty clear to me at this point:
* Almost everyone has access to a wide variety of delicious food, which we on average enjoy eating more of than is required to maintain a healthy weight.
* We don't want the government to forcibly restrict people's food access.
* Research consistently shows that voluntary portion control works occasionally in the short term and not at all in the long term.
* Many people have proposed specific ingredients or nutrient classes that can be adjusted in a person's diet to resolve obesity, but none to date have checked out.
In principle, I suppose, there could be some crazy diet hack we don't yet know about. But why should we expect that to be the case? To be honest, I think a lot of the existing discourse on this topic was just wishful thinking, because before GLP-1s the bottom line was not "some people need a pharmaceutical intervention" but "some people are just gonna be obese and there's nothing we can do to help them".
I would argue that your argument is simplistic and does not account for observed geographical variations.
Japan does not have an obesity epidemic. The US has an extreme obesity epidemic. There does not seem to be any good genetical explanation, there might be cultural based behavioral explanations, but Japanese communities in the US are also more obese than ones in Japan (although less obese than the general US population).
So it is clearly entirely possible for a society to have plenty of easily accessible delicious food, with no major government restrictions in place, and not have an obesity crisis. And there seems to be some particularly bad environmental and/or cultural factor in the US driving the abnormally bad obesity epidemic there, and no intervention before GLP-1 has managed to reverse the trend (not that there have been many). There are a lot of theories about this topic, but no clear scientific consensus beyond "all very sweet things are probably maybe bad".
PS: I am aware that Japans "fat-tax" exists and is technically a form governement restriction, but I would assume that it plays a relatively minor role overall.
I’m not sure cross-cultural comparisons are useful here. One big difference is that friends and family will aggressively police your weight and the amount you eat, with the ideal set far below health standards for normal weight. It’s not clear how you could operationalize that into an intervention, even if you wanted to.
* Almost everyone has access to a wide variety of delicious food, which we on average enjoy eating more of than is required to maintain a healthy weight.
* We don't want the government to forcibly restrict people's food access.
* Research consistently shows that voluntary portion control works occasionally in the short term and not at all in the long term.
* Many people have proposed specific ingredients or nutrient classes that can be adjusted in a person's diet to resolve obesity, but none to date have checked out.
In principle, I suppose, there could be some crazy diet hack we don't yet know about. But why should we expect that to be the case? To be honest, I think a lot of the existing discourse on this topic was just wishful thinking, because before GLP-1s the bottom line was not "some people need a pharmaceutical intervention" but "some people are just gonna be obese and there's nothing we can do to help them".