A lot of fitness models have a low/no sodium diet. They influence people that are looking to live a healthy lifestyle. A result is that people try to cut their salt intake as well. They've heard that eating sodium will make them look bloated.
When you take the salt from your diet, your body will adjust to it. So the moment you eat or drink something with a little extra salt, you'll immediately hold water.
Eating an excessive amount of salt on a daily basis is scientifically proven to be unhealthy. It could increase your blood pressure, cause kidney damage and if you do it long enough it could even cause stomach cancer.
This doesn't mean that you don't need the minerals from salt. Try to stay around 3 gr of salt each day.
It's easier to control your salt intake when you make homemade food. Pre made or microwave meals often contain a lot of sodium, fast (junk) food is even worse.
For people that want to compete or do a photoshoot, use the normal amount of salt all the way up until a day or 2 before the end of your prep. This causes a peak moment when you cut it and if you're timing is good you'll look super shredded on stage.
Don't ever binge after a show or shoot, it's super dangerous! Rehydrate slowly and eat a normal sized meal so your body has time to readjust. You'll be a little bloated the next day, but that will fade very quick.