I think the water is probably most important. Fred and Levi are often away from food for two hours plus, but I do offer them water.
I went away for a weekend, leaving the birds at home. Levi managed to get his food door open, and escaped the cage. He was clipped at the time, so couldn't get back into the cage. I returned home a day early...I don't really know why, but I just wanted to get home. Maybe, I felt that there was something wrong...who knows. I don't know how long he was out, but when I walked in, he was on the floor, yelling to me. His eyes were dull, and he drank for a long time. If I had stayed as per the plan, he would have died of dehydration.