Why am I so thirsty?
I've searched the site but haven't found the answer to this perhaps obvious/ridiculous query. Why is it that you can eat a meal at a restaurant that tastes great and not overly seasoned, but the next day [or even a few hours later] you're drinking literally litres of water and you're parched like the Sahara? This happened to me after eating at an Italian resto yesterday, but has happened to me with all varieties of restaurant cuisine [I must add that it happens about 20% of the time, not all the time]. My point is, if it's the salt, it would have tasted too salty and I would have noticed- if I put even a tad more salt than normal in home-cooked meals, it practically ruins the dish with its overpowering saltiness. If it isn't the salt, then what is it? It's not the alcohol- I usually have one glass of wine, whereas I would have 2 or more glasses at home, so it's not dehydration. I'm stumped! Hounds?
Quite a few people seem to get this reaction when there is more sodium content (ie the combination of salt and MSG and whatever else the resto uses). It may be that everything you ate has salt and or MSG, just below the "salty" level, but the combination from all sources pushes your sodium intake up.
A lot of restaurants add salt in different stages than what a lot of home cooks may do at home. It doesn't taste overtly salty because it's not added at the end (which I find a lot of home cooks to do), but there's a lot of salt in the dish. And the Italian restaurant may use a lot of cheeses in their food which has a lot of salt. If you put cheeses in at an earlier stage of cooking (eg. simmering tomato sauce with parmesan rinds), the cheesiness is not pungent as if you grated it towards the end. But you still get all the salt from the cheese.
If that's not it, you may be sensitive to hidden MSG. It's not only Chinese restaurants that use it. I'm not saying that they'll have a bag of Accent lying around, but it could be hidden in a lot of processed ingredients they use. Thank goodness I don't have the issues some may have with excess MSG like headaches, but after an MSG-laden meal, I need to drink a ton of water.
Another thought is artificial or substitute sweeteners. I get a serious case of dry mouth/throat from every sweetener I have ever tried, including those derived from sugar like Splenda.
If you were to fast for a few days you would become more aware of the high salt content of many restaurant foods. Sometimes the salt content is not obvious. In a tomato sauce that has wine and sugar added the salt will be less noticeable. I had this experience Saturday night after dinner at Grand Sichuan. I kept drinking water throughout the meal. I like to keep 2 bottles of water on my nightstand to take my bedtime medication and supplements. During the night i finished both bottles of water. After dining in a New Orleans type of restaurant I was parched for 2 days. Have you ever noticed that the most used ingredient for Emeril to season with is Salt? Sometimes 2 or 3 times in a single dish.
So it is probably the salt whether you taste it or not.
Ditto what others have said.
It's probably some combination of salt, MSG, and the higher fat content of restaurant meals.