Have you checked out Ellie's suggestions? You already saw that anti histamines can play a part. Maybe part of it too is just getting that metabolism going in full gear again.
I used to think, don't eat if you aren't hungry. Wrong! It started the slow down of my metabolism. So now I do notice myself getting hungry earlier in the day. I snack on carrots and occasionally string cheese. It seems by eating a tad more frequently with smaller portions, I am getting my furnace warmed up a bit more.
Don't fret, it will start to kick in.
kat
Me-53(and learning!) S24, S21, D18, D17 Just keep swimming, Just keep swimming. Dory