Question

Why does too much salt cause swelling of the feet and increase in weight​

Answer 1

If your feet begin to swell, you may be suffering from a condition known as edema. Edema is caused by fluid getting trapped in the space between cells, also known as the extracellular space.

Answer 2

More salt in the diet means the kidneys keep more water in the system. That can have lots of undesirable effects, such as edema (swelling in places like the hands, arms, feet, ankles, and legs); more fluid in general means more blood coursing through veins and arteries.