without training in mathematics and physics people naively think that volume is linear same as distance. it is not.
and what's worse than what you pointed out about how plate sizes kept on growing over the last 5 decades, is the food they put on it has become increasingly higher starch, and higher in omega 6 and oodles of traces of petrochemical solvents and unnatural, toxic chemicals, non-food stuff like xanthan gum and guar gum (literal glues), and then add GMO alien proteins into the mix.
it's not at all any wonder that americans have ballooned and got sicker. it's the food, stupid.