I have liver and kidney issues, so I have to REALLY watch the sodium. Basically, my body retains sodium, which retains water. Depending on your health issues, salt substitutes like Potassium Chloride are not an answer. My doctor says no to that. Ask your doctor if it is okay for you.
MSG is more potent in flavor, which lets you use less of it, but you still have to use it sparingly -- it's not a silver bullet solution.
I have found that after several months of cutting back on salt, I don't notice it is missing. In fact, when I go to a restaurant now, I often find the food overly salty.
I just rely on herbs and spices more when I cook at home, and don't miss the salt anymore.
CD