I have to snack on the course quite a bit, or I'll get jittery and grumpy as my blood sugar drops (especially dramatic when I walk)
I don't generally eat much, but need to. Never was a fan of "Bars", but I came across the Quaker bars "Chewy chocolate chip" granola bars and really like these.
I bring a bottle of water that I refill at the water coolers/jugs. I'll bring a diet coke in a can to start my round, and then it's water after that's gone.