late-night soda swap has my appetite doing weird stuff

i'm usually up till 2-3am playing, and for years my thing was a cold diet soda around midnight. started swapping it for plain seltzer about 3 weeks ago, mostly to see if it helped my sleep and random stomach noise. now i wake up not hungry at all, but by noon i'm basically feral for salty carbs. it's not a huge deal but it's consistent enough that i'm side-eyeing the swap. i didn't change my meals much, still doing the same protein coffee and leftovers, sme med day. only real difference is the soda is gone and i'm drinking more water. could the carbonation/sweetener thing be messing with my hunger cues, or is this just sleep debt catching up? curious if any other late-night people noticed a shift when they dropped diet soda.