Japan is probably evidence that the surrounding food culture matters at least as much as the existence of UPFs. You can sell plenty of processed food without getting the same outcome if portion sizes, eating habits, school meals, and daily activity are different. The marijuana comparison feels like a non sequitur, though.

>Japan has ultra processed foods and they don't seem to have an obesity epidemic.

Most of that's from a much stronger national guidance on weight control + societal expectations, but IIRC they also are gaining weight. Their ultra processed foods (in the salt and preservative sense) are also why they have one of the highest rates of stomach cancer.

> They also don't have a marijuana epidemic.

Not sure if I'd categorize the US as in a marijuana epidemic (and this is coming from someone who doesn't consume it and dislikes being around it) but even if we were, the states with the highest marijuana usage (west coast and NE) and the states with the highest obesity rates (deep south) are almost non-overlapping circles. If we're tying a drug to be obesity rates I'd be much more willing to believe it's the American propensity to chug large amounts of cheap 100-120 calories a pop beer.

Japan is one of the countries where people smoke literally everywhere. As for marijuana, it's highly illegal, it's one of the remnants of the colonial history there as everything apart from smoking and drinking is considered evil due to how China was devastated with opium.

They also have society self enforced limits on bringing harm to society restraining capitalism