Up until Sully was about 5 months, he had really odd sleeping and eating habits. Especially eating...he'd eat sometimes and not others. And we had him on a strict feeding schedule!
So I knew that if he was hungry, he'd have eaten. But he does fine now! Some lunches he doesn't eat much, but I know it's ok b/c he eats TONS for dinner, usually.
But, that's just me and I'm no expert on any dog but Sully