When I first started I had a decreased appetite. That was mostly due to not being used to the numbing effect kava can have on the throat and stomach. It feels weird at first. Doesn't bother me now.
If I eyeball measure the water sometimes I use a little more water that I'd normally drink at one time and that makes me feel a little full though.
I also get massive appetite reduction the next day. This seems to happen with the more heady kava's which makes sense from a pharmacological standpoint. You have kavain which is a mao-b inhibitor and NRI which both can suppress appetite through norandrenegic and dopaminergic signalling. It also has a effect on the hypothalamus which regulates hunger amongst other things.
i would imagine that over time like the others have suggested you gain tolerance to this effect and it is less noticeable. I find tuday etc don't decrease my appetite, but keep me from eating if you know what i mean. The shit is strong.