> From my travels there my impression is of a diet that largely consists of rice and various meats and a high consumption of alcohol and cigarettes. Although there definitely seems to be far less sugar in everything.

That really depends on what you eat, donburis are typically their version of fast food, which as you said consists of some basic elements: rice, protein, veg etc... But just consider that the basic tare has extraordinary amounts of sugar, albeit fermented for long periods of time if done correctly. This is critical, so much of their foods are fermented and pickled and I think having a healthy gut biome is far more important to overall physical and mental health that I think is entirely overlooked in so much of Western Medicine. Kombucha is only a recent phenomena in the West, but how long has something like miso shiro been the accompanied soup of choice in set meals (Teishoku). Yakult has been a thing there since the 30s I think, which is also incredibly sweet!

But sugar is present in a lot of things, the tri-fecta of Japanese flavour is building off of shoyu-mirin-sake (mirin being a sweet sake) but dashi and sugar can often be quite as prevalent as bases.

One of my favorite donburis, gyudon, can be overly sugary for my tastes when others make it and I prefer a more savoury feel to accompany the beef, so I use like 5x the amount of onions (ideally Maui ones) and slow sweat/saute to bring out the natural sugars in the onions to mask my rather overly savoury tare: I use quite a lot of kombu and katsubushi/niboshi in my dashis as I like the brinier taste when I cook as I do in my miso soup. You feel more satiated eating smaller portions this way, too and is a hack/trick to reduce over consumption as you tap into the innate metabolic/feedback satiation mechanisms if you're healthy.

But think about it, Teishoku is a very healthy balanced meal and coupled with their active daily lives in and our of cities you get pretty good averages on healthy people. Japan has many Sociological issues (some outright toxic) that I won't go into depth into that impact their image as the 'pinnacle of health' but those are solid baselines.

The issue you raise is well taken, especially for me whose repertoire is Japanese and has an obsession with topics related to food/diet in relation to health and disease.

And it is definitely a multi-variable equation, but I think diet--especially in contrast to the American one so many of us grew up on--and an active lifestyle (car ownership is super expensive and has lots of complications that promote limited ownership as well as logistical issues in big urban cities) really explains most of the observations.

I'd like to nerd out about ichiju-issai, and the history and significance of Kaiseki and trace the origins of the composition and structure of meals in relation to Seasons, but you get what I'm trying to say.

> Culturally it seems that fitness in general is encouraged, combined with a very different attitude toward being overweight (I had several locals comment that I was a bit fat [my BMI is ~26])

In a World where anything even remotely suggesting people's health is being obviously compromised due to excessive consumption (of all things but specifically food in this case) is considered fat shaming, I find it rather refreshing and it's something I too have adopted. It's not trying to be mean, its just a reminder that things related to diet seem to be out of synch and could explain a wide array of maladies and symptoms, which are often brought up as topics of conversation.