I'd be surprised if the ratios matched up exactly. That'd mean the only factor dictating the level of obesity is food culture. Not likely.

I'm sure Japan has a variety of unhealthy foods, I don't see how that matters. That unhealthy food exists in Japan doesn't tell us anything about how much of it people actually eat.

That's why I linked the video, its author talks about the experience of the average person, here's an exact link: https://youtu.be/lr4MmmWQtZM?t=176.

I cannot stress this enough, the only thing that matters is what is readily available to the average person. That's the determining factor of most people's diets, not what's theoretically possible to purchase.