The question is incorrectly phrased as the "land of the free" has know idea what a kilo of blubber is.
However, the question has merit because IIRC there was a commuter aircraft that crashed which was attributed to overload or incorrect cg because on this particular event all the pax were on the large side of overweight.
I hate it when you are "trapped" in your seat because of an over weight and immobile person in the aisle seat. This surely constitutes a safety risk.
Un-PC I know but I have more sympathy for druggies and alchoholics than I do for over weight folk.
Back in my box
T