I suspect two things, low-calorie diets consisting predominantly of fresh foods and vegetables. And active lifestyle.
It is unreal how much a good diet and walking everyday will change your entire life.
It is unreal how much a good diet and walking everyday will change your entire life.
This is apparently weird even to Chinese people; an image of ramen with rice and roast dumplings on sides amounts to a ragebait to them(as well as to experts in cardiovascular systems), while it's nothing more than a common lunch menu to students and young workers in Japan.
But I digress - my point is, the real traditional Japanese meal is more like half a football worth of rice with vegetable flavored salt, quite unlike idealized modern interpretations thereof.
It is true that rice was always the prestige food consumed by the upper classes, and the peasantry ate rice too, but it was only one of the five staples (gokoku) and was often extended with other grains (mugigohan etc).
In contrast, people in East Asia started cultivating rice 9,000 years ago, and modern Japanese are probably mostly descended from these early rice farmers (who started out in China, then spread to Korea and then Japan) with a substantial contribution from another population called Jomon, which were already in Japan when the heavily-rice-dependent people started to arrive in Japan about 2,300 years ago and who lived mostly by hunting and gathering.
This is relevant because some people here are advocating for everyone to adopt a Japanese-like diet, which might not turn out so well for you unless most your ancestors have 8,000 or 9,000 years of experience getting most of their calories from grains.
This parallels China, where the warm, wet south is rice country but the colder, drier north grows other grains. The five grains (gokoku) idea is itself originally Chinese:
Car culture makes Americans fat and lazy. 40% of US adults are obese. 80% are overweight.
Walking and good food, yeah, that helps. But trains introduce short sprints into everyday life. It starts with "He's too late, he's never gonna catch it... well I'll be damned, he did it." and pretty soon, you're saying "We can catch it, just run!" Everyone on the train has a shopping bag, because trains don't have huge trunks like a car. You want groceries? Carry it. Good exercise. Trains also remove the road rage from your life, the daily stress of defensive driving in a fast moving freeway full of other angry drivers. Trains eliminate the premature death caused by road accidents which not only lower life expectancy directly, but indirectly as bread winners are taken from families. The car exhaust is gone too. Trains reshape how towns are built, with higher density and less parking. More walking! Everything mushrooms out from the decision to travel with trains. It's little wonder why Japan has the lowest obesity rate in the world.
If you'd like a more direct comparison to Japan, try Hong Kong, another place where I have spent a fair amount of time riding the trains. They also have world leading life expectancy.
The Japanese retirement attitude is "I've worked my ass off all my life. Contributing to the society all my life. Finally I have some time to spend on my hobbies! I should be active!" and they pick up quite active hobbies: if you go hiking mountains you'll see many old retired people with serious gears. Also still trains.
Contrast it to ime, western retirement which is more "finally I can relax" and people become sedentary. Hanging around in parks, cafe, or focus more on socializing and diet. And starts to rely more on cars and other senior services.
My father spends all day watching football or horses and has visibly started going senile.