Brain fog often shows up before thirst does. Thirst is not an early warning, it is a late one: the signal generally arrives after you have already lost roughly 1 to 2 percent of your body water. Your brain registers the shortfall sooner, which makes sense for an organ that is about three quarters water. Ganio and colleagues (British Journal of Nutrition, 2011) and Armstrong and colleagues (Journal of Nutrition, 2012) found that mild dehydration around that same threshold was associated with lower mood, more frequent headaches, and tasks feeling harder than they were, in healthy young adults who were not thirsty enough to think anything was wrong. Here is the frame worth keeping: the afternoon slump you reach for coffee to fix is sometimes a water problem. Part 10 of the Food Literacy Path is live today: Your Brain Is 75% Water. Start at dietdiscipline.com/start-here.
