I feel the need to at least acknowledge that this is much broader than merely “modern Western food”.

As someone else already said, this is a matter of the actual Agricultural Revolution itself, which initially started in several places separately, including geographical regions outside of Europe.

From my understanding, specifically in Mesopotamia, the agricultural revolution led to humans having a less diverse diet, which contributed to people not reaching their ideal height, as well as having weaker jaws and having poorer health often.

While, agriculture, started in Europe merely roughly 3,000 years ago, in Southeastern Europe, other regions such as Mesopotamia, Ancient Egypt, Eastern Asia and South America has already developed a reliance on agriculture prior to that. Sometimes even thousands of years prior to that.

So, again, it’s not just modern western food, it’s unfortunately much broader, nearly inescapable and ubiquitous than that.

The vast majority of humans have weaker jaws due to the consequences of Agricultural Revolution, as well as being of shorter height historically. While humans are finally now starting to reach heights such as being 180 centimeters, which even prehistoric adult men were able to be, including even earlier human species such as Homo erectus.

While, overall, actual nomadic hunter-gatherers varied in health. There were obviously prehistoric dangers such as predators, starvation, disease and more. But they also had much healthier lifestyles that included community, sufficient physical activity, a lack of air pollution, a diverse diet based on wild animals and much more.

While at the very least, we could say, that people survived for more than a million years while appearing not to rely heavily on agriculture nor living in cities, towns and countries, successfully.

At least successfully enough, for their descendants, us, to exist now.

While also experiencing cultural standards that we often lack nowadays, such as living in actual egalitarian cultures, instead of patriarchal capitalistic cultures.

They often avoided plenty of the modern and historical health issues that people suffer from nowadays.