Thanks for the article!
Bethany Carpenter

Good question. Indeed taste sensitivities can change dramatically when doing keto (see relevant studies here, here, and here).

Mechanistically, as our bodies get more leptin-sensitive during and after induction, the concentration of sugars in our mouths required to cause a “sweetness” signal decreases (leptin is involved with these receptors as part of its role to help regulate our hunger levels).

There is also a link between our gut bacteria and our sweetness sensitivity, as the bacteria that are used to living off of the refined carbs we feed them urge us to eat an increasing concentration and quantity of the sweet stuff.

As for detecting sweetness from water itself, well, consider that a gift :) It may be that you were so leptin-insensitive before, for example, that pretty much anything will taste sweet if not already sour, bitter, salty and/or umami.