MEGA portions in America in the 60s. The same thing crept into the UK in the 80s - we once ordered a starter in a country pub and cancelled the rest of our order, as did the people at the adjacent table. Think this is to do with food commerce and advertising, all inspired by the US. My guy had a theory that it began with immigrants coming from countries where people were starving, and then just continued.
And this is hugely politically incorrect, and will doubtless offend, but the re-introduction of a three letter word beginning with an 'F' and ending with a 'T' might help. Also, we really don't need snack food in so many outlets, like eg. WH Smiths, where I was once offered a mega Toblerone - ugh! I had a lovely auntie, when I was little, who was plump and cuddly, but I can't equate her with these creatures who look like overstuffed sofas on legs.
German voters slide inexorably to common sense …
Expensive free range chicken was tasteless!
