I wondered if it was some sort of expectation that when you ordered food at a restaurant that there was always excess you could take home in a ‘doggy bag’ which seems to be fairly common in the US but not typical in my experience in NZ or Australia.

I’ve definitely become accustomed to it and I can now eat that full American sized serving :(

Funnily enough, most of the time the cheeseburgers are smaller here in the US than NZ!

Oh my god, yes.

"Free refills" also didn't become standard until some time in the 90s. In the 80s, a refill cost money and often the cups were smaller to begin with. You'd buy a pitcher (just like with beer) if you wanted a lot at a bit of a discount. You can see this on an ad on a pizza hut in the skater movie Gleaming the Cube, near the end of the film. Now the idea of buying a pitcher of soda makes no sense because everywhere has free refills, but almost none did in the 80s. In the early 90s some places did but it was often just during certain hours (lunch, say) as a draw. It spread from there until it became normal, fast-food joints started letting you fill (and re-fill) your own cup, et c.

That said, this 2011 study from Cambridge University says portion sizes have not grown significantly.

https://www.cambridge.org/core/journals/proceedings-of-the-n...