Just because the FDA banned steroids and hormones from being injected into live chickens, doesn't mean the poultry industry didn't find another way to plump em' up...post mortem.
Dead raw chickens in the poultry industry are injected with a saline concoction and other "natural flavors" that typically make up 25% of the bird's weight. And yes, you're paying for that enhanced weight at checkout.
So if you're on a low sodium diet, you should avoid factory farmed chicken brands, which are typically marketed to consumers in the grocery store who blindly purchase whatever is placed in front of their face.
Apologies if that sounded too salty.