Interesting chain of causation:
The pigs' largely soy and corn-derived food source strongly contributes to their getting shockingly fat, to a degree you almost wouldn't believe an animal could get, and causes their fat to be very high in linoleic acid. Very abnormally so, compared to the wild condition. That itself is a large part of the contribution to the animals getting so fat.
Humans eat that fat, with that very high linoleic acid, contributing towards their getting shockingly fat in turn, particularly if part of an entire pattern of high linoleic-acid intake.
(An individual human with some intake of it may not get fat, particularly if physically active. It's not an absolute cause. Also, some linoleic acid is necessary, so as a component of an otherwise good diet, it doesn't have to be a problem.)