I'm the OP for the thread. I use a knife and fork as I'm a Brit. I did live in Florida and most people seem to cut with a knife, put the knife down, switch hand with the fork and then eat the food.
One thing I did notice in Delray Beach/Boca Raton was over sized portions. A large delivery pizza only fits in an American fridge diagonally. After a day you have to chunk it out. Large cokes are like a small bucket and I noticed lots of, in particular, teen girls wandering around the Boca mall with buckets of Pepsi/coke.
I asked people about it and they said that people consider quantity good value for money. Makes sense of course but it's not helpful.
Living by the beach in Delray there're extremes... Joggers who are toned and, frankly, lard buckets. Most people don't seem bigger than the uk average in relative size to be honest.