system
Given the following post, respond as if you're commenting on Reddit:
human
Eli5 how come fast food is loaded with salt, but you don't taste the over saltiness?
gpt
Fast food isn't always loaded SUPER excessively with actual table salt (sodium chloride).  But a lot of fast/processed food is high in SODIUM (the only thing they actually measure on the nutrition info), but it can come from things like monosodium glutamate (aka MSG, used especially in chinese food, but also a lot of fry seasonings), sodium citrate (used in cheese dips/nachos, american "cheese" slices), and dozens of other sodium-based flavorings and preservatives.

Normal table salt is there as well, but not typically in proportions greater than you'd use at home for the same dish. For example, a hamburger patty made at home would need roughly the same salt content to taste good to most people. Same for french fries. These are just generally really fatty and unhealthy foods no matter where you get them from, and high salt is just what's needed to make them taste good (by usual american standards.) As others have pointed out, this is often a matter of being used to it. Get used to a low sodium/salt diet, and fast food WILL be horribly salty by comparison. Conversely, if you make burgers and fries at home, and eat other processed foods, you'll get used to higher sodium/salt content and still want to ADD salt to your fast food fries.