It's just what the human palate does. It adapts to circumstance. Skip sugar and sweet stuff for a few months and when you try it again everything tastes much sweeter than before. Same with salt. Same with acidity. And surely other things I haven't tried and corroborated with peers.

Water went from boring as dirt to kind of tasty.

Anything carbonated still tastes good but there's a hard limit of one per day.

I still like the usual foods. I also lost 20 pounds!

I dunno about a week, but it only took me about three weeks to switch from regular soda to diet soda, back in the mid-nineties, and I really didn't like the taste of diet soda when I started. After 2-3L a day of diet for several weeks regular Mountain Dew tasted sickeningly sweet and I no longer wanted it. ¯\_(ツ)_/¯