I live on an island with 1.2 million other people, about 90 percent of whom are Chinese …

And about 90 percent of them are skinny.

OK, not all of them are stick-thin. But the overwhelming majority of Chinese here are not fat. Which is a rate of non-tubbiness we can only dream of, back in the States.

I have marveled, time and again, how thin people here are. Young, semi-young and old. Male and female.

I don’t know female sizes of clothes, but I do know that if you ran a men’s clothing line here, and you made men’s trousers and none of them had waist sizes under 34 inches … you would go broke in a month.

How do they do it?

Far as I can tell, the local Chinese exercise very little. Aside from walking a bit, to and from the subway. They go up and down stairs, in subway stations, but they almost all stand still on escalators while they’re doing it. So they’re not climbing hundreds of steps per day. They certainly aren’t out jogging in any numbers. They aren’t riding bikes.

And it’s not as if they’ve cut out all the carbs. Rice is a staple here. That and noodles, which are all starch as well.

Yet this is an island of 95-pound women and 135-pound men.

OK,  yes, lots of Chinese, here in Hong Kong, are what we might call “small-boned” — the opposite of what supportive moms back home describe as their “big-boned” children. And, yes, there is some legitimacy to that. Americans of European ancestry tend to be bigger, in all respects, than the Chinese here in HK.

(On a subway, if I am standing, I typically can see over the heads of everyone on the train, from one end to the other, and I no longer am 6 feet tall.)

But this goes beyond that. It’s not just smaller ribcages that explains it.

Exercise isn’t it. Unless hundreds of thousands of Hong Kongers are working out in the privacy of their apartment buildings.

So, that leaves genetics and diet.

It’s not what they eat, because they eat lots of starches and lots of deep-fried this and that. And they love pork.

I believe it’s how much they eat. Generally modest quantities.

Portions here are very small. Your average American could go into a Chinese restaurant here, of any sort, and wonder “where is the rest of my meal?” all the time. If you order chicken, you get chicken — and nothing else. Unless you ask for it. You order fried rice, that’s all you get. The fried rice. No side dishes. No bread, even.

And it’s not as  much chicken/pork/fish as you are used to getting.

Not many buffets here, either.

And the grocery stores? Small portions in there, too.  You can’t buy huge bags of chips or monster trays of cookies or 5-gallon buckets of ice cream. It just isn’t offered. Everything is a dinky size.

So, anyway, maybe you get conditioned to small portions, from small packages, and you know that from birth, and you live in a culture where eating is seen as a means of keeping up your energy to work longer and harder — as opposed to doing it for pleasure or because you’re bored, which seems to be the case for some Americans.

I’m still thinking about this. But there is no denying: The Chinese are skinny and we Americans are fat. That’s one of the reasons they live longer, on average, than we do.

Maybe some of it is genetic. Maybe some of it is diet, or cultural.

Whatever it is, it might do us all some good to take a closer look at what the Chinese here are up to. It makes for tiny women and skinny men. It makes a seriously heavy person basically nonexistent. I’m not sure I’ve seen a 300-pounder since I got here, and I could find one in five minutes in any Wal-mart in America.

There is something here we can learn from. It could be something not exactly helpful, like, “see to it that your parents are Chinese.” Or it could be handier. Such as “limit your portions, buy in small quantities, live in small spaces with tight tolerances.”

I’m going to think more about this.