I eat as normal. I always have. I've never changed anything with how or what I eat on WI day. The only difference for me is that WI day I eat my tea later than normal.
On a normal day I normally eat my tea around 7-7.30pm, but on WI day, because I leave home to get to group at 6.45pm, I don't have enough time to make and eat something before class, so I eat when I get home, normally around 8.30pm.
I also take something to group with me to snack on once I've been weighed so my belly doesn't start grumbling
I always drink the same too. 2 litres each day at work.
I only really have salads for lunch, so I'm not eating loads at lunchtime anyway. And I still snack in the afternoon if I'm peckish.