Before I truly appreciated the importance of eating a balanced, sufficiently satisfying daily breakfast, I would either skip it or wolf down something pretty junky & convenient on the way out of the door which then usually made me super hungry and/or put me in a bad mood by 10am. This went on for years until I figured out that eating a more nutritious meal in the morning and then again at lunchtime, tapering off to a light meal or snack in the evening actually worked far better for my sanity (!), metabolism and personal eating habits.
Eating a nutrient dense meal at the start of the day not only lays the foundations for sensible eating choices throughout the day but also keeps blood sugar levels at bay which can cause the mood swings. Here are some great breakfast ideas (such as using avocados and making smoothies) from this link to Mind Body Green that can help balance those all important blood sugars.