People need to eat within one hour of waking, or else their body goes into starvation mode and holds on to fat and burns muscle instead (if the person exercises). That first meal of the day should primarily be protein. Cereal/grains (anything resulting in a high glycemic load) sets one up for cyclic hunger which can lead to binge eating in some people.
Not eating for long stretches (such as from sometime before one goes to bed until a few hours after waking) causes difficulty thinking clearly and can result in anxiety or mood difficulties if one's brain is predisposed to them (because the brain is attempting to 'run on fumes'). The changes in the brain's neurotransmitters that this causes can take a long time to restabilize afterwards (i.e. they don't just go away the next time one eats). If not eating right away on waking is a pattern, then it can take a couple weeks for the brain to stabilize if one eats regularly in the morning every one of those (14) days. [Just like every other major neurotransmitter change: it takes a minimum of two weeks for stability to start to show in the brain again. It can take longer before all the 'downstream' neurotransmitters to stabilize from such a pattern.]