I was on a four and half hour flight on Sunday - I thought there would be a 'snack' on the plane. So, I packed and pnb on wheat and an apple. They then came around with breakfast - honeynut cherrios, muffin, lowfat milk, banana. I said, "no thank you" and ate my bagged food even though that muffin was calling to me.
(but I'm quite surprised that they had Honey Nut Cheerios - I thought nut snacks had been banned due to concerns about nut allergies, people in a confined space re-breathing the same air, etc)