Great post cdm guy
As one of the older posters around here (48), I've noticed a shift in the role of food in our culture since I was a kid. Food has become much more central, kids and adults alike surrounded by tasty treats everywhere they go. For instance, there didn't used to be food courts in malls because you ate at home and generally could get through a couple hours shopping without a snack. People didn't used to buy pop as part of their regular diet - in the 70s, if you saw somebody buying a case of pop, they were having a party.
It's harder to listen to one's hunger/satiety when surrounded by the constant clamour of tasty treats being advertised at you, or present everywhere, in airports, train stations, malls, roadsides, etc.
We evolved in an environment where we went hungry sometimes. But people have been conditioned to panic if they get slightly peckish, and rush to stuff their faces.
The rise of bottled water is symptomatic of this phenomenon IMV. There didn't used to be any such thing as bottled water as a commercial advertised product. Now there's people all over the place sucking back on water bottles like overgrown babies, taken in by the bottled water industry's falsehood that we require 8 glasses of water per day for health, instead of listening to our bodies and drinking when we're thirsty. I've had people say to me, "If you wait til you're thirsty, it's too late." Too late for what? I'm going to go hypernatremic and lapse into acute renal failure steps from the water cooler?
PS: I'm a skinny person and in school I had lots of skinny Asian friends. And we'd frequently go to Chinatown and fill up on lots of rice, spicy noodles, seafoods, and veggies. I think you're sort of right about chopsticks having a moderating effect on intake, though there are some folks who bring the bowl up to their mouths and hoover that rice pretty effectively with chopsticks.