Adding salt to fizzy water helps you feel full because your body has special nerves that respond to salt and signal satisfaction.

The brain uses two different signals to control salt craving: one slow signal that says 'we need salt' and one fast signal that says 'you tasted salt, stop now'—and they work together to make the mouse eat just enough.

Just turning on the salt-craving brain cells doesn't make mice eat salt fast—unless you also trigger the angiotensin signal, then they immediately start licking salt like crazy.

Mice stop wanting salt almost instantly when they taste it in their mouth—even before the salt gets into their body—and this happens because a specific brain signal turns off when salt is tasted.

If you remove most of the salt-craving brain cells, mice no longer seek out salt—even when they’re very low on it.

These brain cells only make mice want salt—not water or food—and don’t affect how much they move around.